Computer Hardware

Book II Chapter 1Knowing Your Motherboard 67 Finding Out What’s on a Motherboard Figure 1-2: A ZIF socket on the motherboaard Socket 7 ZIF Socket Figure 1-3: A Pentium II, using SEC packaging. Remember that classic Pentium chips are inserted into socket 5 or socket 7, whereas Pentium II processors are inserted into slot 1. With newer Pentium processors, such as Pentium III and Pentium 4, Intel has moved away from SEC. The Pentium III is placed in Socket 370, and the Pentium 4 is placed in Socket 423 or Socket 478.68 Finding Out What’s on a Motherboard SIMM/DIMM sockets When you look at a motherboard, one of the first items that should stand out is the processor; the next things you will usually notice are the memory slots used to install RAM into the system. There are typically two types of sockets for installing memory: single inline memory module (SIMM) sockets and dual inline memory module (DIMM) sockets. Original Pentium systems typically have either four 72-pin SIMM sockets or two 168-pin DIMM sockets to install memory, and newer motherboaard today use DIMM sockets and no SIMM sockets. There are no rules as to how many SIMM or DIMM sockets a motherboard manufacturer may use, as you can see with Figure 1-4. Figure 1-4 shows a motherboard with four 72-pin SIMM sockets and two DIMM sockets used to hold memory. SIMMs have been phased out and are only available on older motherboards. Figure 1-4: SIMM and DIMM memory slots on a motherboaard Four 72-pin SIMM slots Two 168-pin DIMM slots 2.631Book II Chapter 1Knowing Your Motherboard 69 Finding Out What’s on a Motherboard When installing SIMMs on Pentium motherboards, you have to install them in pairs. When installing DIMMs, though, you can install them individually. The reason for the difference is that when installing memory, you must fill a memory bank, which is the size of the processor’s data path. That is, if you install 72-pin (32-bit) SIMMs onto a Pentium (64-bit) motherboard, you have to install two modules to fill the 64-bit data path of the processor. DIMMs are 64-bit memory modules — the same number of bits as the data path of the CPU — which is why you can install only one at a time. For more information on memory banks and installing memory, check out Book II, Chapter 3. Cache memory Cache memory increases performance by storing frequently used program code or data that can be later accessed by the processor. Cache memory is much faster memory than normal RAM and, as a result, is more expensive. The system stores data accessed from RAM in cache memory when the data is accessed the first time, making subsequent requests to the same data faster because the data is accessed from cache (faster than RAM) for subsequuen calls. All processors today have integrated cache memory, which is known as level 1 cache. Integrated cache is cache memory that is built into the processoor while nonintegrated cache — known as external cache — is built outside the processor, typically on the motherboard. The types of cache are as follows: ✦ L1 (level 1) cache: Cache integrated within the processor ✦ L2 (level 2) cache: Cache located outside the processor, usually on the motherboard Older motherboards implemented cache memory as rows of DIP (dual inline package) chips placed directly on the motherboard. This area was sometiime even labeled “cache.” Unfortunately, you can’t expect a motherboard to be well labeled; if you find labels (in English), consider it an added bonus! For more information on chip packages, check out Book II, Chapter 2. Other systems have implemented the cache as a memory module, so you might see an empty slot on the motherboard that looks like a SIMM slot but will really hold a cache module. A lot of times, this is labeled as “cache” on the motherboard. Figure 1-5 shows L2 cache on an older motherboard.70 Finding Out What’s on a Motherboard Figure 1-5: L2 cache located on a motherboaard L2 Cache L2 cache is usually located on the motherboard near the processor. That way, data travels over a shorter distance from cache to processor, thus increasing overall system performance. Also, today’s processors implement both L1 and L2 cache in the casing of the processor. For more information on cache memory, refer to Book II, Chapter 3. Motherboard chipset Each hardware component in the system has circuitry responsible for managing a specific hardware part. This circuitry is the controller for that specific piece of hardware. For example, access to memory is controlled by the memory controller, the hard disk is managed by the hard disk controller, and the keyboard is managed by the keyboard controller. The combination of computer chips that hold the logic for these controllers is the motherboard chipset. Together, the computer chips make up the chipsse control communication from the CPU to each of the hardware devices in the system.Book II Chapter 1Knowing Your Motherboard 71 Finding Out What’s on a Motherboard Two chips that make up a big part of a motherboard’s chipset are the North Bridge and the South Bridge. The North Bridge chip is responsible for communiccatio from the CPU to memory, the CPU to the PCI Express bus (more on PCI Express later in this chapter), and the Advanced Graphics Port (AGP) device (more on AGP later in this chapter). The South Bridge chip is responsible for communication between the CPU and other devices, such as PCI, ISA, and IDE devices. These two chips contain the bulk of the logic that allows a CPU to communicate with other hardware. Figure 1-6 displays the relationship between the processor and the North Bridge and South Bridge chips. Figure 1-6: The relationship between the CPU and the motherbooar chipset. CPU AGP Memory North Bridge IDE PCI South Bridge Locating the North Bridge and South Bridge chips on a motherboard can sometimes be challenging. The North Bridge chip is typically the second largest chip (after the processor) and also typically contains a heat sink or a fan on top of the chip to keep it cool. The North Bridge chip is typically located between the processor and the AGP slot, and the South Bridge is normally located farther from the processor — usually beside the PCI slots, as shown in Figure 1-7. Notice in the figure that the North Bridge chip bears the manufacturer name “AOpen” on it, and the South Bridge is the chip above the PCI slots.72 Finding Out What’s on a Motherboard Figure 1-7: The North Bridge and South Bridge chips on an AOpen motherboaard South Bridge North Bridge BIOS chip The basic input-output system (BIOS) is the low-level program code that allows all the system devices to communicate with one another. This lowleeve program code is stored in the BIOS chip on the motherboard. Locating the BIOS chip on the motherboard is easy; it is usually rectangular and generally features a label with the manufacturer’s name and the year the chip was manufactured. Some of the popular manufacturers are AMI, AWARD, and Phoenix. The BIOS chip is a read-only memory (ROM) chip, which means that you can read information from the chip, but you can’t write to the chip under normal circumstances. Today’s implementations of BIOS chips are EEPROM (electricaall erasable programmable ROM), which means that you can get special software from the manufacturer of the BIOS to write to the chip. Why would you want to erase the BIOS? Suppose, for example, that your BIOS is programmed to support a hard disk up to 200GB in size, but that you want to install a new, larger hard disk instead. What can you do about it? You can contact the BIOS manufacturer and get an update for your BIOS chip, which is usually a software program. (In the past, you generally had to install a new chip.) Running the software program writes new instructions to the BIOS to make it aware that there are hard disks bigger than 200GB and provides instructions for dealing with them. But before new instructiion can be written, the old instructions need to be erased. The BIOS chip also contains code that controls the boot process for your system. It contains code that will perform a Power-on Self-Test (POST), which Book II Chapter 1Knowing Your Motherboard 73 Finding Out What’s on a Motherboard means that the computer goes through a number of tests, checking itself out and making sure that it is okay. After it makes it past the POST, the BIOS then locates a bootable partition and calls on the master boot record, which loads an operating system. Figure 1-8 shows a BIOS chip on a motherboard. For more information on the system BIOS, refer to Book II, Chapter 4. Figure 1-8: A BIOS chip located on the motherboaard ROM BIOS Chip Battery The computer keeps track of its inventory in what is known as the complemenntar metal-oxide semiconductor (CMOS). CMOS holds a listing of system components, such as the size of the hard disk, the amount of RAM, and the resources (IRQs and I/O addresses) used by the serial and parallel ports. This inventory list is stored in CMOS RAM, which is a bit of a problem because RAM loses its content when the power is shut off. You don’t want the computer to forget that it has a hard disk or forget how much RAM it has installed. To prevent this sort of problem, a small watch-like battery on the motherboard maintains enough energy that CMOS RAM doesn’t lose its charge. If CMOS RAM loses its charge, CMOS content is lost. Figure 1-9 identiffie a battery on the motherboard. For more information on CMOS, check out Book II, Chapter 4.74 Finding Out What’s on a Motherboard Figure 1-9: The battery (on the motherboaard used to maintain a charge to CMOS RAM. CMOS battery Expansion slots Most motherboards have one or more expansion slots, which add functionaliit to the computer. For example, assume that your computer doesn’t have sound capability: You can install a sound card into the expansion slot to add that capability to your system. Expansion slots come in different varieties, and it is extremely important to understand the benefits of each type. I discuss these issues later in the chapter, in the section titled “Understanding Bus Architectures.” For now, I just want you to be able to identify the expansion slots on the motherboard. If you look at the motherboard, you can see a number of expansion slots. There are probably some white, narrow PCI slots on the board, as well as a tan-colored AGP slot (used for video cards). You might also see some larger black slots; these are ISA slots used by older devices. Most motherboards today do not have ISA slots, or might have only one. Figure 1-10 displays ISA, PCI, and AGP expansion slots used to add expansion cards to the system. For more information on expansion slots, see the “Understanding Bus Architectures” section, later in this chapter.Book II Chapter 1Knowing Your Motherboard 75 Finding Out What’s on a Motherboard Figure 1-10: Expansion slots (AGP, PCI, and ISA) on a motherboaard AGP slot PCI slots ISA slots Ports and connectors A number of ports on the back of the motherboard connect the keyboard, mouse, printer, and other devices to the system. This section identifies those ports. Figure 1-11 displays a number of built-in input/output (I/O) ports on the back of an ATX motherboard. Figure 1-11: Built-in ports on the back of an ATX motherboaard Serial ports Most motherboards have serial ports integrated directly into the board. The serial ports are also known as communications (COM) ports. They are called serial ports because they send data in a series — a single bit at a time. If eight bits of data are being delivered to a device connected to the COM ports, the system sends the eight bits of data, one bit at a time, in single file. Typically, there are two COM ports — COM1 and COM2 — on each system.76 Finding Out What’s on a Motherboard The official standard that governs serial communication is known as RS-232, and you might see serial ports referred to as RS-232 ports. You usually connect an external modem or a serial mouse to a serial port. Each device is used for communication. For example, a modem allows your computer to talk to another computer across phone lines, and a serial mouse allows you to communicate with the system. Figure 1-12 shows two serial ports connected to a motherboard. Figure 1-12: Integrated ports on the back of an ATX motherboaard Keyboard Mouse USB Serial 2Parallel Serial 1 Serial ports on the back of the motherboard are one of two types: ✦ DB9-male: A serial port with 9 pins ✦ DB25-male: A serial port with 25 pins Parallel port Another type of connector on the back of a motherboard is the parallel port, also known as the printer port, or LPT1. The parallel port gets its name by being able to send information eight bits at a time. Whereas serial ports send only one bit at a time in single file, parallel ports can send eight bits in one operation — side by side, rather than single file. Refer to Figure 1-12 to see a parallel port connected to a motherboard. The parallel port, known as DB25-female, has 25 pin holes and is located on the back of the motherboard. Looking back at Figure 1-12, you can see the parallel port located above the two serial ports.Book II Chapter 1Knowing Your Motherboard 77 Finding Out What’s on a Motherboard Do not confuse a serial port with a parallel port. A serial port is a male port (the port has a number of pins in it), whereas a parallel port is a female port (contains pin holes). You connect the parallel port to a printer by using a parallel cable with a differren type of connector at each end. On one end of the cable is a DB25 conneccto that attaches to the parallel port on the back of the computer. The other end of the cable (the end that connects to the printer) has a 36-pin Centronics connector. A standard printer cable has a different type of connector on each end. One end has a DB25-male connector with 25 pins, and the other end has a 36-pin Centronics connector. Video adapter In the past, a motherboard came with a built-in video adapter, sometimes called a video card or video controller. The video adapter converts digital data from the processor and prepares the information to be displayed onscreen. Figure 1-13 displays a video adapter port, which you can identify by the three rows of five pins. The video port is a 15-pin female port. Figure 1-13: A video adapter port. Video adapter Because many systems today use the ATX motherboard form factor, they have an AGP or PCIe slot to hold the video adapter. This means that the video adapter is not integrated into the motherboard like it was in the past. Figure 1-14 shows how information flows from the computer system to the monitor. The following steps mirror the numbers in Figure 1-14.78 Finding Out What’s on a Motherboard 1. The video adapter is responsible for receiving digital data from the processsor which instructs the video adapter on how the images are to be drawn on the screen. 2. The video adapter stores the information about drawing the images in its memory and starts converting the information into analog data that the monitor can understand. 3. The data is sent in analog format from the video adapter to the monitor. Figure 1-14: How information flows from the processor to the display. CPU Video Adapter Monitor 1 2 3 Keyboard/mouse connectors The mouse and keyboard connectors on motherboards today are most likely PS/2 style connectors or USB connectors. Focus on PS/2 connectors for now. A PS/2 connector is a small, circular six-pin connector. In Figure 1-15, you can see the keyboard and mouse connectors on the left side of the diagram.Book II Chapter 1Knowing Your Motherboard 79 Finding Out What’s on a Motherboard Figure 1-15: PS/2 connections for a keyboard and a mouse. Mouse connector Keyboard connector Older motherboards might have a DIN keyboard connector, also known as an AT connector, which you can see on AT and Baby AT motherboards. These systems did not have any other ports on the back of the system, so you needed to insert an I/O card for other ports (such as serial and parallel ports). Sound Most motherboards today have built-in sound capabilities, allowing you to connect speakers and a microphone to the computer. Figure 1-16 shows the integrated sound ports on a motherboard. The three different ports on the integrated sound card are ✦ Line-in: The line-in port (typically blue) allows you to connect many audio sources to the system. ✦ Line-out: The speaker port (typically green) allows you to connect speakers to the computer. ✦ Microphone: The MIC-in port (red) allows you to connect a microphone to the system for recording. Network interface card and modem A number of systems today have built-in network support via an integrated network interface card (NIC), or network card for short. These systems might have a built-in modem as well. The built-in network card has an RJ-45 port on the back of the system that looks like an oversized telephone jack, as shown in Figure 1-17.80 Finding Out What’s on a Motherboard Figure 1-16: Sound ports on a system. Line-out Line-in MIC-in Figure 1-17: An RJ-45 port. RJ-45 port USB ports Universal Serial Bus (USB) is a high-speed serial technology that transfers data at 12 Mbps (USB 1.0), 480 Mbps (USB 2.0), and up to 5 Gbps for USB 3.0. One of the major benefits of USB is the fact that all USB devices use the same type of connector, so you won’t have to guess which ports to connect the mouse, keyboard, or scanner to. If they are all USB devices, they conneec to the same type of port on the computer! Because USB 3.0 is still fairly new, the popular USB standard used today is still USB 2.0, but that will change quickly. USB 2.0 has a transfer rate of 480 Mbps, which is much faster than the original USB 1.0 standard. When using USB 2.0 devices, be sure that you also have USB 2.0 drivers installed to leverage the performance benefits of your USB 2.0 devices. USB devices also support daisy chaining. For example, you can connect Device A to the back of the computer and then connect Device B to Device A, and so on. You can connect as many as 127 devices to a system using USB. Figure 1-18 identifies the USB ports on the back of an ATX motherboard.Book II Chapter 1Knowing Your Motherboard 81 Finding Out What’s on a Motherboard Figure 1-18: USB ports on the back of a motherboaard USB ports A USB device that connects to the computer and then has other devices connected to it is considered a hub device. If you do not have a USB device that can act as a hub device, you can purchase a specific USB hub that allows you to chain four or more other devices off it. With a USB hub, you can easily increase the number of USB ports your system has by connecting USB devices to the hub and then connecting the hub to the back of the computter Figure 1-19 shows a USB hub. Figure 1-19: A USB hub with four ports. FireWire (IEEE 1394) When USB 1.0 was introduced, it ran at 12 Mbps. This was a fairly good speed for most types of devices but was a little too slow when it came to multimedia devices, such as digital video cameras. Typically, these types of devices use a FireWire connection, which has a transfer rate of up to 400 Mbps and supports 63 devices in a chain. This is a huge jump compared with the USB 1.0 standard. The official standard that defines FireWire is known as the IEEE 1394. Be sure to remember that for the exam!82 Finding Out What’s on a Motherboard Just like USB has different versions with faster transfer rates, so does FireWire. The second version of FireWire is defined as the IEEE 1394b standaar and transfers data at 800 Mbps! This second version of FireWire is also known as FireWire 800. Figure 1-20 shows a digital video camera being plugged into a FireWire port. Figure 1-20: A digital video camera being connected to a system by the FireWire port. For the exam, remember that the original version of FireWire runs at 400 Mbps and is known as IEEE 1394. The second version of FireWire, FireWire 800, is also known as IEEE 1394b but runs at 800 Mbps. Also, FireWire suppoort 63 devices in a daisy chain. For more information on common ports and connectors — such as keyboaard mouse, serial, parallel, USB, and FireWire — read Book III, Chapter 1. Power connectors All the devices connected to the motherboard need to get power from somewhere, so the power supply is connected to the motherboard, which supplies power to the board and its components. The following sections discuss power connectors on older and newer motherboards.Book II Chapter 1Knowing Your Motherboard 83 Finding Out What’s on a Motherboard Older motherboard power connectors Figure 1-21 shows power connectors on an older motherboard. There are power cables coming from the power supply to connect to the motherboard with very unique connectors on the end. These power connectors coming from the power supply that connect to the motherboard may be labeled as P1 and P2; or on some systems, P8 and P9. Figure 1-21: Power connectors on an older motherboaard Motherboard power connector You have to be extremely careful to make sure that the connectors on the cable coming from the power supply to the motherboard are inserted properrly or you could damage the motherboard. Often, these connectors are keyed (meaning that they can go in only one way) so that you cannot put both of the connectors in the wrong way. These older power connectors supplied power in 5 volts (V) and 12V. ATX power connectors Newer ATX motherboards use a different power connector than the one shown in the preceding section. The ATX power connector supplies 3.3V, 5V, and 12V. The ATX power connector, shown in Figure 1-22, is typically labeled as P1.84 Finding Out What’s on a Motherboard Figure 1-22: The ATX power connector on an ATX motherboaard ATX power connector Some systems, like ones that use the Pentium 4 boards, use an additional power connector (the P4 connector), which supplies an additional 12V to the ATX board. Figure 1-23 displays the P4 power connector. Figure 1-23: The P4 power connector on an ATX motherboaard For more information on power supplies and their connectors, check out Book II, Chapter 6.Book II Chapter 1Knowing Your Motherboard 85 Finding Out What’s on a Motherboard Drive connectors You need to be able to identify the different types of connectors that link hard drives to your system. As you might already be aware, the hard drives are used to store information permanently on the computer, but to access that information the drives have a physical connection to the system via the motherboard. The four major types of drives in systems today are IDE (Integrated Drive Electronics), SATA (Serial Advanced Technology Attachment), SCSI, and floppy drives. Each type of drive has its own type of connection on the motherboard. Before you purchase a hard disk to add to the system, you need to be aware of what types of drives your motherboard supports. IDE connections IDE drives have been around since the 1980s, and although the technoloog has improved from a performance perspective, IDE drives connect to the system the same way they always have. If your motherboard supports IDE, you will have two IDE connectors that are made up of 40 pins each, as shown in Figure 1-24. Figure 1-24: IDE connectors on the motherboaard You connect the drive to the connector on the motherboard by using a 40-wire or 80-wire IDE ribbon cable. This ribbon cable typically has two connectors on it — one end connects to the drive and the other end conneect to the motherboard. You can also find IDE ribbon cables with three connectors that allow you to connect two drives to each IDE connector on the motherboard. This means that you can have up to four IDE devices on a system. Figure 1-25 shows an IDE ribbon cable connector.86 Finding Out What’s on a Motherboard Figure 1-25: A 40-wire IDE ribbon cable. When connecting the IDE ribbon cable to the drive and motherboard, the colored wire on the ribbon cable connects to pin 1 on the connector. This is the pin-1 rule. Pin 1 is normally labeled on the motherboard and drive. If it isn’t labeled, see whether the manufacturer has labeled pin 40 — if so, pin 1 is at the other end! IDE controllers is a popular term used in the computer industry for the IDE connecttors Although in theory, these are not controllers, this term is used in the industry to describe the IDE connections on the motherboard. The actual IDE controller — the circuitry located on the circuit board on the drive itself — is responsible for controlling the flow of information to and from the drive. SATA connections Limitations of the IDE architecture have kept its data transfer rate around 150 MBps. As drives become more powerful, a new standard is needed. The first new standard to replace IDE — SATA — is the popular drive technology in desktop and laptop computers. SATA can reach transfer rates of up to 600 MBps! This is quite a bit (450MB, to be exact) faster than the 150 MBps offered by high-end IDE drives. SATA uses its own unique four-wire cable to connect to the motherboard. Figure 1-26 shows a SATA cable connected to the SATA connector on the motherboard. Notice that the cable is quite a bit thinner than the IDE ribbon cable; this allows for better airflow in the system and improves overall temperaatur control of the computer.Book II Chapter 1Knowing Your Motherboard 87 Finding Out What’s on a Motherboard Figure 1-26: A SATA cable connected to the motherboaard Unlike IDE drives, you cannot connect more than one SATA drive to a connecctor For example, if your motherboard has two SATA connectors, you can connect only two SATA drives to the system unless you purchase a SATA card that has additional connectors. SATA is a hot-swappable technology that allows you to remove and add drives while the system is still running. This adds huge benefits over IDE solutions. eSATA connections eSATA (External SATA) allows for external drives to connect to a system via a SATA port instead of the typical USB or FireWire port. In the past, external drives were enclosures that held SATA drives, but the interface to connect the enclosure to the computer used USB or FireWire. This created overhead because the SATA interface is translated to USB or FireWire, which is slower than SATA. With eSATA connections on the motherboard, you can connect to the external drive using eSATA to leverage SATA speeds with no translatiio drawbacks! The eSATA device, which requires its own power source because it is an external device, can have an external SATA cable length of two meters. The eSATA cable is a special cable designed to help prevent electromagnetic interference (EMI). The eSATA cable has also been designed to handle more than 5,000 insertions and removals of the drive; the current internal SATA cable is suited for only 50 insertions and removals. If your motherboard does not have an eSATA port, you can purchase an expansion card to add to the computer, providing the eSATA ports.88 Finding Out What’s on a Motherboard SCSI controller Some high-end machines, particularly those designed for use as servers, might have a controller on the motherboard with 50 pins on it. This is the footprint of a SCSI (Small Computer System Interface) controller. Because SCSI devices outperform IDE devices, SCSI controllers are extremely popular for servers (which have greater hard disk access and storage needs than regulla desktop computers). To connect a SCSI drive to the 50-pin SCSI connectto on the system, you use a 50-wire ribbon cable. IDE uses a 40-pin connector that a 40/80-wire ribbon cable connects to, and an internal SCSI connector has 50 pins that connect to a 50-wire ribbon cable. Lab 1-1 and Lab 1-2 will help you identify the major motherboard components on the motherboard. Lab 1-1 and Lab 1-2 can be found in the Labs.pdf file in the Author directory of the book’s companion CD-ROM. Floppy disk connectors Located very close to the IDE connectors on the motherboard, you should see a smaller floppy drive connector that contains 34 pins instead of the 40 pins found with the hard drive IDE connectors. The floppy drive connector on the motherboard is used to connect the floppy drive to the motherboard using a 34-wire ribbon cable. When connecting the floppy drive to the system, notice that the wires on one end of the ribbon cable are twisted. This twisted end must be conneccte to the floppy drive. The opposite, untwisted end connects to the motherboard. Also note that one wire of ribbon cable is colored, usually red, which indicates wire 1. Like the IDE drives, you need to connect wire 1 to pin 1 on the motherboard and on the floppy drive. To find out more information about IDE, SATA, SCSI, and floppy drives, check out Book II, Chapter 5. Jumpers and DIP switches A jumper is a set of pins that have a plastic cap enclosed over them to create an electrical connection. The plastic cap contains a piece of metal that makes contact with the pins and creates the electrical circuit. The circuit that is created enables a feature on the motherboard. Most motherboaard (and older expansion cards) use jumpers to implement different settings. Figure 1-27 displays a jumper on an expansion card.Book II Chapter 1Knowing Your Motherboard 89 Finding Out What’s on a Motherboard Figure 1-27: Identifying a jumper. Jumper Notice in the figure that the jumper has three sets of pins that the cap may be placed over. The idea behind the three sets of pins is that each set of pins would enable a different setting. For example, looking at Figure 1-27, the three different sets of pins might be used to assign three different interrupt requests (IRQs) to the card. You choose which IRQ is assigned to the card by setting the jumper over a set of pins. Keep in mind that you no longer assign IRQs with jumpers; that was something was done years ago. (For more information on IRQs, check out Book III, Chapter 4.) Today, you find jumpers on motherboards, hard drives, CD-ROM drives, and DVD drives. Many different features can be enabled or disabled on a motherboard by using jumpers. For example, there usually is a jumper on the motherboard used to clear the CMOS password of a system, to change the voltage supplied to the processor socket, or to change the speed of the motherboard. To know what jumper to set, check the documentation for the motherboard. Another popular component of a motherboard or expansion cards in the past that was used to enable or disable different features is the dual inline package (DIP) switch. A DIP switch (as shown in Figure 1-28) is a set of switches that can be turned on or turned off to enable functionality on the board. To know what to set for on/off combinations, consult the documentatiio for the board.90 Identifying the Types of Motherboards Figure 1-28: A DIP switch. ON 1 2 3 4 5 6 Identifying the Types of Motherboards Now that you understand some of the major components of the motherbooar (system board), it is important to mention the different motherboard form factors. A motherboard form factor just describes the dimensions of the motherboard and the layout of the motherboard components. You need to understand the different motherboard form factors because you can’t just take any motherboard and place it in a computer case. For example, you must put a full AT motherboard in a full AT case, a Baby AT board in a Baby AT case, and an ATX board in an ATX case. Figure 1-29 shows the three major types of motherboards to give you an idea of size and shape differences between the three types. Figure 1-29: Looking at different motherbooar form factors. Full AT Baby AT ATXBook II Chapter 1Knowing Your Motherboard 91 Identifying the Types of Motherboards Full AT The full AT motherboard — 12" wide and 11" long — is easily recognized by the fact that it has only a keyboard connector on the back of the motherbooar and that it contains no other I/O ports. The full AT suffers from a problem with accessing some items on the motherbboar because the drive bays hang over the motherboard. This configuratiio makes installing and troubleshooting motherboard components very difficult. Another problem with the layout of the full AT board is that the expansion cards, after having been inserted into the systems, cover the processor. This situation leads to cooling problems because ventilation is insufficient to keep the chip from overheating. Figure 1-30 displays a full AT motherbooar being installed in a full AT case. Figure 1-30: A full AT motherbooar in a full AT case. Baby AT The Baby AT motherboard form factor had been one of the most popular motherboard types until recent years. The Baby AT board is 8.5" x 10". You can easily identify this motherboard because it usually has a DIN (multipin, round) keyboard connector on the top-right corner of the board. This keybooar connector is the only I/O connector on the back of the motherboard.92 Identifying the Types of Motherboards A Baby AT board is about two-thirds the size of a full AT board and typically incorporates a Socket 7 ZIF slot for classic Pentium processors. The Baby AT board usually has a mixture of ISA/EISA and PCI slots located on the motherboard and includes a Plug and Play BIOS. Figure 1-31 shows a Baby AT motherboard and identifies the popular components. Figure 1-31: Baby AT motherbooar components. Flash BIOS 32-bit PCI slots (4) Serial 1 and serial 2 ports (COM 1 and COM 2) Keyboard connector Mouse connector (PS/2) Power input connector Floppy drive connector Parallel port (LPT1) Primary EIDE connector Secondary EIDE connector SIMM sockets (4) DIMM sockets (2) L2 cache CPU Socket 7 (ZIF) Chip set 16-bit EISA slots (3) Take a minute to consider some of the key components on the Baby AT motherboard. You can see the Socket 7 ZIF slot at the bottom of the motherbboar where the processor is to be installed. Also notice the SIMM and DIMM sockets (on the right side of the motherboard); these house the Book II Chapter 1Knowing Your Motherboard 93 Identifying the Types of Motherboards system memory. To the left of the SIMM and DIMM slots are the primary and secondary EIDE connectors (sometimes called controllers) for connecting the hard drives to the board. To the left of the EIDE controllers are the types of expansion slots that are used: here, four PCI slots and three EISA slots. Above the PCI slots is a silver circle, which is the CMOS battery. LPX/NLX In an effort to allow computers to take up much less space, a slimline desktto system was designed with a smaller motherboard. After the era of the Baby AT came the LPX (low profile extended), which was then replaced by NLX (new low profile extended) motherboard. Both motherboard types served the same purpose — to create low-profile computers. The NLX motherboard is identifiable by the I/O ports along the back of the motherboard. This motherboard is unlike the full and Baby AT because they incorporated only the keyboard connector. Comparatively, the NLX provides a keyboard and mouse connector, serial and parallel ports, and a video connector. The NLX form factor — 9" x 13.6" — uses a riser card to house the bus architecttures The riser card typically connects to the side of the motherboard and is then secured along the side of the case. Figure 1-32 shows an NLX motherboard with a riser card. (I cover bus architectures in the section, “Understanding Bus Architectures,” later in this chapter.) Figure 1-32: An NLX form factor motherboaard 94 Identifying the Types of Motherboards ATX In 1995, Intel wanted a motherboard that would support the Pentium II processso and the new AGP slot, so the ATX form factor was built (shown in Figure 1-33). The ATX board — 7.5" x 12" — has most of the I/O ports integraate directly into the board, including USB ports. Figure 1-33: The position of the I/O ports on an ATX motherboaard Pentium II I/O ports AGP video adapter card The ATX motherboard incorporates the I/O ports and includes an AGP slot for high-performance video cards. Figure 1-33 displays the ports on the back of the ATX motherboard. Note how they are clustered in the left corner of the board and do not spread across the length of the board like they do with the NLX form factor. The ATX board introduced a 100 MHz system bus and has been increased to speeds of 533 MHz and higher. The ATX motherboard has one AGP slot for the video card, which means that the built-in I/O ports on the back of the board do not have a built-in video card like the NLX. The ATX board also has soft power support, which allows software developers to create software that controls the startup and shutdown of the system. The ATX form factor rotated the Baby AT components by 90 degrees so that any cards inserted into the bus architectures would not cover the processor and prevent proper cooling. Figure 1-34 shows an ATX motherboard. Figure 1-34 also highlights some of the common components on the ATX board. Notice, for instance, slot 1, where a Pentium II chip can be inserted. Newer versions of the ATX motherboard use a ZIF socket to house the processoor Notice also, in the top-right corner, the BIOS chip with a white label on top of it. At the top of the figure, you can identify the EISA and PCI slots, and located in the center of the board is an AGP slot. The hard drive controllers are located on the left side beside the three slots that hold the DIMM memory.Book II Chapter 1Knowing Your Motherboard 95 Identifying the Types of Motherboards Figure 1-34: The ATX motherbooar is very popular in today’s systems. EISA slots AGP chip Serial 2 port Parallel port Serial 1 port (2) USB ports PS/2 keyboard & mouse CPU slot I (Pentium II) ATX power connector DIMM sockets Primary EIDE connector Floppy drive connector Secondary EIDE connector AGP slot PCI slots Chip set ROM BIOS PS/2 USB Serial 1 Serial 2 Parallel microATX and FlexATX Smaller versions of the ATX motherboard are the microATX and FlexATX. The microATX motherboard form factor is 9.6" x 9.6" and can fit in either a micro-ATX case or a normal ATX case, known as a full ATX case. Measuring 9" x 7.5", the FlexATX is smaller than the microATX but can fit in an ATX or a microATX case. FlexATX is not as popular because the size of the motherboard limits how much you can expand the system. Figure 1-35 shows a microATX board. The important point to make here is that when you purchase a motherboard, you must ensure that it fits your case. For example, if you have an ATX case, you know that an ATX or microATX motherboard can fit in that case. Another motherboard form factor that was designed to replace the ATX form factor and create smaller, low-profile systems is the Balanced Technology eXtended (BTX) motherboard form factor.96 Understanding Bus Architectures Figure 1-35: Compare ATX motherbooar size (left) with a microATX motherbooar (right). ATX motherboard microATX motherboard Lab 1-3 will help you summarize distinguishing features of popular motherbooar form factors. Lab 1-3 can be found in the Labs.pdf file in the Author directory of the CD-ROM. Understanding Bus Architectures The motherboard has a number of expansion slots that can expand the computter’ capabilities. When the system is first purchased, a computer has only so many capabilities. The nice thing is that you can expand on those capabilities by purchasing cards to add to the expansion slots, or bus slots. Expansion slots, um, expand what the computer can do. The problem is that there are different types of expansion slots in the system, so when you purchase a sound card or network card, you have to make sure you get the right type. In the following sections, I show you the different types of expansiio slots and also compare their characteristics.Book II Chapter 1Knowing Your Motherboard 97 Understanding Bus Architectures Another term for the expansion slots is bus slots. A number of different bus architectures have been developed over time. You need to be able to identiif the differences between each of these architectures and also to know which ones are more popular today. ISA The Industry Standard Architecture (ISA) was the first major expansion bus architecture. It was originally developed as an 8-bit architecture and then evolved into a 16-bit architecture. The ISA bus architecture has a speed of 8 MHz, which is extremely slow by today’s standards. Figure 1-36 shows two 16-bit ISA slots; note that the ISA slots are the black slots in the system. Figure 1-36: Identifying ISA slots on the system. ISA slots One of the reasons why you still see 16-bit ISA slots in some earlier Pentium or Pentium II systems is because companies typically had a number of ISA network cards in the office from previous systems. When a company upgraded to the Pentium or Pentium II, it was nice not to have to purchase new network cards because earlier Pentiums had ISA slots. Most systems today, though, no longer have ISA slots. Figure 1-37 shows a 16-bit ISA netwoor card.98 Understanding Bus Architectures Figure 1-37: A 16-bit ISA network card. MCA One of the major downfalls of the ISA bus architecture is its performance. It runs at only 8 MHz, and it is only a 16-bit architecture. That was fine years ago, but everything evolves, and new and improved standards arise. The Micro Channel Architecture (MCA), developed by IBM, is a 32-bit architectture The MCA architecture runs at 10 MHz and is not compatible with ISA. You usually find MCA slots in high-end IBM machines, such as those that might be used as a server. ISA is an 8-bit or 16-bit technology that runs at 8 MHz. MCA transfers informattio in 32-bit chunks and runs at 10 MHz. With MCA, IBM came up with a feature called bus mastering. Bus mastering works like this: Devices in the bus don’t have to send information through the CPU if they want to talk to one another — they just send the information directly. This takes some of the workload off the processor and allows it to perform other tasks. Bus mastering became an important feature in future bus architectures. Figure 1-38 shows an MCA card.Book II Chapter 1Knowing Your Motherboard 99 Understanding Bus Architectures Figure 1-38: An MCA network card. EISA In 1988, the industry standard for expansion cards was still ISA, but bus architectures had already been created that performed better. So a number of companies got together with the goal of extending ISA while maintainiin backward compatibility so that companies could use their existing ISA cards. As a result, the Extended Industry Standard Architecture (EISA) was developpe as a 16-and 32-bit architecture. The big advantage to EISA is that it maintains support for the ISA cards that some companies already have in large quantities, and it also supports 32-bit EISA cards. EISA also included the major advancement in expansion bus technology that MCA created — bus mastering. Because both ISA and EISA cards fit into the same slot, they keep the same speed of 8 MHz. The bus architecture holds both 16-and 32-bit cards because the EISA slots have two levels. The EISA cards have very deep edge connectors that fill the two levels (32-bit) of the slot, but ISA cards fill only the top level (16-bit). Figure 1-39 shows an EISA slot and the two different levels in the slot: one level for the ISA card to fill and the other level for the EISA card to fill. Figure 1-39: How a EISA slot is organized. ISA Card EISA Card 16-bit 32-bit Side view100 Understanding Bus Architectures VESA In 1992, the Video Electronics Standard Association (VESA) developed a bus architecture that outperformed ISA. VESA is a 32-bit architecture that suppoort bus mastering and runs at the same speed as the processor, which, when VESA was created, was around 25 to 33 MHz. Because the bus runs at the speed of the processor, developers called this VESA local bus, or VLB. VESA slots are typically used for video cards. Remember that EISA is an extension on ISA and is a 16-bit or 32-bit technologgy For backward compatibility, EISA runs at 8 MHz. VESA is a 32-bit architecctur that runs at the processor’s speed. It is generally used for video adapters. VESA slots are extremely easy to identify because they are tan and because they act as an extension to the ISA slot. You will notice the black ISA slots; right beside them might be a tan slot. The VESA card fills the entire ISA slot and the additional extension to make the full 32-bit path for VESA. This allows an ISA card to be inserted into the slot for backward compatibility. Or, with the extension slot, the VESA slot can hold a VESA card. Figure 1-40 shows a VESA slot. Figure 1-40: A VESA slot, which is an extension of an ISA slot. ISA slots VESA slot PCI Peripheral Component Interconnect (PCI) has two flavors: 32-bit cards and 64-bit cards. When Pentium systems hit the market, their motherboards featuure both ISA/EISA slots and PCI slots. When buying a new card today, you would most likely buy a PCI device for one of the PCI slots in your system. The 32-bit version of PCI has a speed of 33 MHz, and the 64-bit version of PCI runs at 66 MHz. PCI also supports bus mastering. One of the other major benefits of PCI is that it is a Plug and Play architecture. If you are running a Book II Chapter 1Knowing Your Motherboard 101 Understanding Bus Architectures Plug and Play operating system, such as Windows, and your computer has a Plug and Play BIOS, the system resources (such as IRQs and I/O addresses) are dynamically assigned for PCI components. PCI slots are easily identified on the motherboard as the small white slots, usually located alongside the AGP slot. Figure 1-41 identifies PCI slots on a motherboard. Figure 1-41: Installing a card into a PCI slot on a motherboaard PCI slots PCMCIA Personal Computer Memory Card Industry Association (PCMCIA) is a unique type of expansion bus architecture because of its small size. PCMCIA is popular in laptop computers. After all, how can you get a big network card like the one in a desktop computer into a little laptop to add network suppoort The answer is that you can’t; you have to purchase a PCMCIA network card for the laptop to add network support. PCMCIA cards, also known as PC Cards, are a little bit larger than a credit card and can fit into your back pocket (although I don’t suggest that you put one there). Figure 1-42 shows a PCMCIA network card.102 Understanding Bus Architectures Figure 1-42: A PCMCIA network card. Canadian quarter PCMCIA network Card PCMCIA (say that five times fast!) is a 16-bit architecture that runs at 33 MHz, supports Plug and Play, and is also a hot-swappable technology. That is, you can insert and remove PCMCIA cards without first shutting down the system. PCMCIA has three different types of slots: type 1, type 2, and type 3. Table 1-1 shows the different PCMCIA slot types and the types of devices you can find in the different types of slots. Table 1-1 PCMCIA Slot Types Slot Name Thickness Types of Devices Type 1 3.3mm Memory cards Type 2 5.0mm Modems/network cards Type 3 10.5mm Removable drives Type 1 cards were originally used to add memory to laptop computers or personal computers. This is where the “personal computer memory card” part of the PCMCIA name comes from. PCI is a 32-or 64-bit technology, runs at 33 MHz, and supports Plug and Play. PCMCIA is the expansion bus architecture used by laptop computers and is a 16-bit architecture that runs at 33 MHz.Book II Chapter 1Knowing Your Motherboard 103 Understanding Bus Architectures AGP Advanced Graphics Port (AGP) has been around since the Pentium II processso appeared in 1997. It’s a 32-bit bus architecture that runs at 66 MHz, which is twice the speed of the PCI bus. Many older motherboards have one AGP slot to hold an AGP video card. The performance gain from the AGP port comes not only from the increase in speed, but also because the AGP bus has a direct path to the processor so that information travels quickly from the processor to the AGP card. Figure 1-43 shows an AGP slot beside some PCI slots. Figure 1-43: An AGP card in an AGP slot. AGP slot AGP can run in different modes, and the different modes dictate the speed of the bus. 1x mode runs at 66 MHz (266 MBps), 2x runs at 133 MHz (533 MBps), 4x runs at 266 MHz (1.07 GBps), and 8x runs at 533 MHz (2.2 GBps)! PCI-X One of the newer bus architectures to arise on the market over the last few years is the Peripheral Component Interconnect Extended (PCI-X) bus architectture Because PCI-X uses the same connector style as PCI, it is totally compattibl with PCI in the sense that it can hold PCI cards. So, a motherboard with PCI-X slots can also house older PCI cards — and that is a great feature!104 Understanding Bus Architectures Like PCI, PCI-X is a 32-bit and 64-bit bus architecture and is available in four different speeds: 66 MHz, 133 MHz, 266 MHz, and 533 MHz. PCI Express PCI-X is compatible with PCI by being able to hold PCI cards and also sendiin data in parallel (multiple bits at one time), but the PCI Express (PCIe) bus architecture takes a totally different approach. PCIe is a serial bus that does not support existing PCI cards. The PCIe slot, shown in Figure 1-44, is the smaller black slot and is much smaller than a normal PCI slot, so it can’t possibly house a PCI card. Figure 1-44: A PCI Express slot on a motherboaard PCI Express slot PCIe uses data lanes to transfer the information within the bus architecture. A data lane delivers an amazing transfer rate of 250 MBps per lane. PCIe has different implementations, each of which has a different number of lanes identified by a multiplier. For example, PCIe with only one lane is known as x1, and a PCIe bus with eight lanes is known as x8. PCIe can thus reach fast transfer rates by implementing additional lanes. For example, current graphiic cards for PCI Express have 16 lanes that provide a transfer rate of 4 GBps (16 x 250 MBps) — which is twice the rate of AGP 8x, which runs at 2 GBps. Most motherboards today have a combination of PCI and PCI Express slots. You can find systems with PCI Express at x1, x2, x4, x8, x16, and x32. The PCI Express slot gets bigger with each multiplier. For example, Figure 1-44 shows a PCI Express x1 slot: the black slot, about 1" long. AMR and CNR Audio/Modem Riser (AMR) is a newer bus architecture that adds a modem and audio card to the system. AMR allows the two components to be incorporrate into a single card to reduce cost. Figure 1-45 shows an AMR slot on a motherboard. Communication and Network Riser (CNR) is another bus architecture that has come out in recent years, used to implement LAN, audio, and modem functionality all in one.Book II Chapter 1Knowing Your Motherboard 105 Performance Considerations Figure 1-45: An AMR slot on a motherboaard AMR slot As far as the “real world” and the exam are concerned, you need to be extremely strong in the area of bus architectures. A big part of servicing computers is installing network cards, sound cards, and video cards. These components come as PCI, PCI Express, or AGP cards today. You need to know how to look at a system and say, “We are going to buy a PCI network card for this system.” Lab 1-4 will help you identify the different performance characteristics of each of the standard bus architectures. Lab 1-4 can be found in the Labs. pdf file in the Author directory of the CD-ROM. Performance Considerations When you want to improve a motherboard’s performance, one of the first things you should do is check the motherboard speed. For example, some systems today have 600–1500 MHz motherboards. To find out the speed of the motherboard, check the board documentation. You can get a performaanc increase from a faster motherboard. Another performance consideration occurs when you add expansion cards to the system. You should first evaluate what expansion slots are free and then purchase a card that will give you the best performance. For example, when you need to buy a network card, start by looking at what expansion slots are free. If only two slots are free — say, an ISA slot and a PCI slot — 106 Getting an A+ your choices are then obviously limited to an ISA network card or a PCI network card. Because PCI outperforms ISA, however, you would be better off purchasing a PCI network card. You can also get a performance increase from motherboards that have more cache memory. Look at the motherboard to see whether there is a place to install some Level 2 (L2) cache. L2 cache can dramatically increase performance because it is generally closer to the processor than the system memory (RAM) and is a faster type of memory than the system memory. Bottom line: The more cache memory you install, the better the motherboaard’ performance. Getting an A+ This chapter introduces you to a number of key components of the motherbooar and different motherboard form factors. The following is a list of the key points to remember when dealing with motherboards: ✦ The motherboard (or system board) is the computer component that interconnects all other components. ✦ Serial (COM) ports come in two flavors: DB9-male and DB25-male. Parallel ports come in only a DB25-female port. ✦ The two main types of cache memory are L1 and L2 cache. L1 cache memory is integrated into the processor, and L2 cache is contained outsiid the processor but in the processor casing or on the motherboard. ✦ IDE supports two devices in the IDE chain, whereas EIDE has two channeel with two devices in each channel (a total of four devices). ✦ A number of major motherboard form factors are available: Full AT, Baby AT, NLX, and ATX, to name a few. Motherboard form factors differ in the size of the board and the layout of the components stored on the board. ✦ You may add components, such as a sound card or network card, to the computer by inserting an expansion card into one of the expansion slots in the system. ✦ ISA was the popular bus architecture for years, but because of its limitatiion (16-bit architecture and a speed of 8 MHz), it has been replaced by the PCI bus architecture. PCI is a 32-bit/64-bit architecture with a speed of 33 MHz. ✦ AGP and PCI Express are the common bus architectures used to insert a video card in today’s systems. ✦ You may increase the performance of the system by using a faster motherboard or by purchasing better-performing expansion cards.Knowing Your Motherboard Prep Test 1 What was the original motherboard speed of the ATX board? A ❍ 33 MHz B ❍ 60 MHz C ❍ 66 MHz D ❍ 100 MHz 2 Which bus architecture supports 32-bit/64-bit cards and transfers information at 33 MHz? A ❍ ISA B ❍ EISA C ❍ AGP D ❍ PCI 3 Which motherboard component is responsible for charging the CMOS RAM so that CMOS can maintain its data? A ❍ Battery B ❍ BIOS chip C ❍ CMOS chip D ❍ Power supply 4 How many pins does a standard IDE controller have? A ❍ 33 pins B ❍ 40 pins C ❍ 50 pins D ❍ 20 pins 5 Which of the following best describes a Baby AT motherboard? A ❍ Uses slot 1 B ❍ Runs at 100 MHz C ❍ The only I/O port is a keyboard port on the back. D ❍ Incorporates AGPKnowing Your Motherboard 6 How many devices are supported in a USB chain? A ❍ 10 B ❍ 27 C ❍ 127 D ❍ 255 7 How many pins does a standard floppy drive controller have? A ❍ 34 pins B ❍ 40 pins C ❍ 50 pins D ❍ 75 pins 8 Which bus architecture might be found in older IBM servers? A ❍ ISA B ❍ MCA C ❍ VESA D ❍ EISA 9 What type of cache memory will you find on a motherboard? A ❍ L1 B ❍ L2 C ❍ SDRAM D ❍ SRAM 10 Which type of memory module supports 32-bit data chunks? A ❍ DIMM B ❍ Cache C ❍ SIMM D ❍ Video 11 Which bus architecture runs at 8 MHz and supports 16-bit ISA cards? A ❍ MCA B ❍ AGP C ❍ PCI D ❍ EISAKnowing Your Motherboard 12 What is the bus architecture used in laptop computers? A ❍ PCI B ❍ PCMCIA C ❍ EISA D ❍ ISA 13 Which of the following best describes AGP? A ❍ AGP slots have a direct path to the processor to help increase performance of AGP devices. B ❍ AGP cards run at 33 MHz. C ❍ AGP runs at 66 MHz and gets access to the processor through the PCI bus. D ❍ AGP stands for Advanced Graphics Port and is used to install additional video memory. 14 Which PCMCIA card type is used for modems? A ❍ Type I B ❍ Type II C ❍ Type III D ❍ Type IV 15 Which port is typically used for a modem? A ❍ USB B ❍ LPT1 C ❍ COM1 D ❍ LPT2 16 When connecting a floppy drive to the system, which end of the ribbon cable connects to the floppy drive? A ❍ The end with a red stripe B ❍ The end with a twist C ❍ The end with a blue stripe D ❍ The end without a twist 17 What are the labels given to the power connectors that supply power to the motherboard? A ❍ P1 and P2 B ❍ P22 and P2 C ❍ PT1 and PT2 D ❍ PS1 and PS2Knowing Your Motherboard 18 How many pins are in the end of a parallel cable connector that connects to the computer? A ❍ 36 B ❍ 40 C ❍ 25 D ❍ 33 19 Which port sends information 8 bits at a time, side by side? A ❍ COM1 B ❍ LPT1 C ❍ COM2 D ❍ USBKnowing Your Motherboard Answers 1 D. The ATX board had an original motherboard speed of 100 MHz. Older boards, such as the Baby AT, had motherboard speeds of 60 and 66 MHz. See “ATX.” 2 D. The PCI bus architecture is a 32-bit and 64-bit architecture that runs at 33 MHz. AGP runs at 66 MHz, and both ISA and EISA run at 8 MHz. Review “PCI.” 3 A. The battery is responsible for maintaining a charge so that the CMOS RAM doesn’t lose its information. The BIOS chip stores the core system code that allows all the devices to communicate. Check out “Battery.” 4 B. An IDE controller has 40 pins to allow a 40-wire ribbon cable to connect a hard disk or CD-ROM to the motherboard. A floppy controller uses 33 pins, and 50 pins are used by internal SCSI devices. Peruse “IDE connections.” 5 C. The Baby AT motherboard uses a DIN connector as the keyboard connector and is the only I/O port found on the Baby AT and the full AT motherboards. Both slot 1, which is the processor slot for Pentium II processors, and the AGP slot that is used by video cards, exist on the ATX board. Take a look at “Baby AT.” 6 C. A computer can support up to 127 USB devices in a USB chain. Peek at “USB ports.” 7 A. A floppy drive connector has 34 pins, and an IDE connector has 40 pins, and internal SCSI devices have 50 pins. Look over “Floppy disk connectors.” 8 B. In the past, you were likely to see MCA in older IBM servers because IBM developed the MCA bus architecture. Study “MCA.” 9 B. Level 2 (L2) cache is the type of cache memory that is found on motherboaards whereas Level 1 (L1) cache is found in the processor. Choices C and D are not types of cache memory. Refer to “Cache memory.” 10 C. 72-pin SIMM modules are 32-bit modules, but a DIMM is a 64-bit memory module. Examine “SIMM/DIMM sockets.” 11 D. The EISA bus architecture runs at 8 MHz and supports ISA cards. MCA does not support ISA, AGP runs at 66 MHz, and PCI runs at 33 MHz. See “EISA.” 12 B. The bus architecture used in laptop computers is called PCMCIA (Personal Computer Memory Card Industry Association). The other three choices are bus architectures available to desktop computers. Review “PCMCIA.” 13 A. The AGP slot runs at 66 MHz and has a direct path between the slot and the processor so that information will not have to travel through one of the slower buses. AGP stands for Advanced Graphics Port and is used to install a video card, not video memory. Check out “AGP.”Knowing Your Motherboard 14 B. Type II cards are used for network cards and modems. Type I cards are used for memory upgrades, and Type III cards are used for removable drives. Peruse “PCMCIA.” 15 C. COM1 is a serial port that is typically used for modems or serial mice. LPT ports are parallel ports that are generally used to connect printers. Take a look at “Serial ports.” 16 B. The floppy ribbon cable has one end that is twisted; that twisted end must be connected to the floppy drive. Look over “Floppy disk connectors.” 17 A. P1 and P2 are the typical labels given to a motherboard’s power connectors. Study “Power connectors.” 18 C. A parallel cable has a different style of connector at each end of the cable. The end that connects to the computer has 25 pins, and the end that connects to the printer has 36 pins. Refer to “Parallel port.” 19 B. Parallel ports send information in 8-bit chunks, side by side; LPT1 is the only parallel port listed. The other three ports are serial ports that send information 1 bit at a time. Examine “Parallel port.”Chapter 2: Picking Your Processor Exam Objectives ✓ Understanding CPU characteristics ✓ Identifying popular CPUs ✓ Identifying sockets ✓ Installing a processor Although all components of the computer function together as a team, every team needs a leader — someone who gives instructions and keeps everyone working toward the same goal. If any PC component were considered the team leader, it would probably be the central processing unit (CPU), also known as the processor. The key word here is central, which implies “center” or “focus.” The CPU can be considered the focus of the computer because it controls a large number of the computer system’s capabilities, such as the type of software that can run, the amount of total memory that the computer can recognize, and the speed at which the system will run. In this chapter, you get a look at some of the features of the CPU that are responsible for regulating the capabilities of the computer system. This chapter also discusses the importance of the CPU and its role as a PC componnent and also identifies some of the main characteristics that make one CPU better than another. When preparing for the A+ exams, it is important that you are comfortable with terms like MMX, throttling, and cache memory. You also want to be sure that you are comfortable with the differences between various processors. For example, what makes a Pentium 4 better than a Celeron? Which AMD processor competes with the Celeron? All these are questions you should know the answer to before you take the A+ Certification exams, and this chapter helps you find out the answers. Good luck! Understanding Processor Terminology In this section, I cover some basic terms that describe characteristics of differren processors, past and present. The exam might not ask for the specific definition of each term, but understanding the terms will help you answer the related questions in this topic area.114 Understanding Processor Terminology Processor speed Processor speed is how fast a processor executes its instructions or commannds This speed was originally measured in millions of hertz, or megaheert (MHz), per second. A hertz is also known as a clock cycle, and a processor can execute code at every clock cycle. Thus, a processor operating at a measly 1 MHz per second can execute one million tasks every second. Processors today now measure their speed in gigahertz (GHz) per second. A gigahertz is one billion clock cycles per second — so the CPU can execute tasks a billion times per second! Original CPUs had a speed of 4.77 MHz, and systems at the time of this writing are running over 3.0 GHz. Although processor speed is not the only factor affecting performance, in general, the faster the processor, the faster the system. Data bus A city bus is responsible for transferring people from one location to another. In the world of computers, a bus is responsible for delivering data from one location on the PC to another. Data bus is the term used to define the pathway between the processor and memory. Because the processor accesses information from memory so often, an entire bus — the data bus — is dedicated to this action. The larger the data bus, the more data can be carried from the CPU to memory in one clock cycle. Here’s an illustration. Say 50 people needed to go from one end of the city to the other, but a city bus had only 25 available seats. The solution? The bus would make two trips. Hmm. Wouldn’t getting a larger bus be more efficient? If you upgraded the bus to 50 seats, the bus would have to make only one trip to transfer the 50 people from one end of the city to the other, which increases the efficiency of the public transit system. The data bus works the same way, only it transfers data in the form of bits. A single bit is either a one or a zero. All data processed by the computer is in the form of bits. The data bus has a full capacity point at which it cannot handle any more bits of data, just like the bus system in the city has a full capacity point (measured in seats). If a processor has a 16-bit data bus, it can deliver — at most — 16 bits during a single clock cycle. If the same processor needs to deliver 32 bits of information, it has to take two trips: sending 16 bits during the first clock cycle and the remaining 16 bits during the next clock cycle. Taking that same 32 bits of information and processing it on a 32-bit processor means that the information will be delivered in one trip — one clock cycle — as opposed to two, which increases the overall efficiency of the system.Book II Chapter 2Picking Your Processor 115 Understanding Processor Terminology Address bus Figure 2-1 shows how system memory is organized like a spreadsheet, in rows and columns. These rows and columns make up blocks that can be written to and read from. If you want to store information in one of the blocks, you have to reference the location by address. For example, you may store data in cell B2. Figure 2-1: How system memory is organized. 1234 A B D 5 C To store information into system memory, your processor has to give an address that points to a particular storage location, only the address doesn’t look like B2. It looks something like 10, or maybe 11, which are two completely different memory locations. As a result, the data would get stored in two different blocks. Your processor accesses memory locations through the address bus. If, for example, the address bus is two-bit, the processor has two address lines from the processor to system memory. The address lines carry signals that specify locations in memory, each with an on/off state. A 1 represents an on state, and 0 represents an off state. The combination of the on/off states of both address lines at any given time is how a reference to an area in memory is made. The left side of Figure 2-2 illustrates a processor making a reference — or call — to address 10. The left side of the figure shows a reference to address 11. These two address calls reference completely different locations in memory. If you add another address line to the address bus, the processor can access even more possible addresses because the processor has more variations with three bits than with two. A two-bit address bus can make a reference to four possible memory addresses (2 × 2), but a three-bit address bus can make a reference to eight possible memory addresses (2 × 2 × 2). Therefore, the address bus dictates how much physical memory the processor can access. For example, an old 80286 processor has a 24-bit address bus, which means that it can access 16,777,216 (224) memory addresses, or 16MB of system memory. Newer processors have 36-bit address buses, which allows them to access 68,719,476,736 memory addresses, or 64GB of memory.116 Understanding Processor Terminology Figure 2-2: Accessing two different memory addresses with the address bus. A B Memory CPU Address= 10 1 0 Memory CPU Address= 11 1 1 Registers Registers are storage areas within the processor used to store data temporarril for manipulation later. They are used to store and process data and perhaps write back the result of the processed data. The benefit of storiin this information in the registers — instead of in memory — is that the processor contains the information and does not have to retrieve it from memory, which takes time. It is as if information to be processed were in your pocket, rather than across a room, where you would have to walk all the way over and pick it up. Having information in your pocket means it can be accessed much more quickly, saving time and increasing performance. Registers give a processor quicker access to data; the more registers a processso has, the more data it can store. Registers are measured in bits. A processor with 16-bit registers has 16 containers into which a programmer can choose to store information. Comparatively, a processor with 32-bit registers has twice as many containeer that it can use to store information. Cache memory The processor accesses information that resides in system memory, which is a slower process than if the information is stored in the processor’s own special high-speed memory, known as cache memory. When the information is sitting in system memory and the processor sends a request for that informattion the request goes to the memory controller, which manages data in memory. The memory controller finds the data in memory, retrieves it, and delivers it to the processor. Throughout this entire process, the processor is simply waiting around for the information. Thus, many newer processors include their own special high-speed memory within the processor’s chip.Book II Chapter 2Picking Your Processor 117 Understanding Processor Terminology When the processor retrieves information from slower system memory, it then stores it in the high-speed cache in case the processor wants to access the information a second time. The benefit is that the second time the data is needed, it is sitting in the high-speed memory located on the processor chip. The processor does not need to sit around and wait for the data to come from system memory — again, increasing overall performance. Cache memory is integrated right into the processor’s chip and is made up of static RAM (SRAM). For more information on SRAM check out Book II, Chapter 3. Cache memory is very expensive because it is much quicker than regular system memory. As a result of this extra memory being integrated into the processor chip, the processor becomes more expensive than a processso that has less or no cache memory. The two types of cache memory are Level 1 (L1) cache and Level 2 (L2) cache. L1 cache is built into the processor, whereas L2 cache resides outsiid the processor. In the past, L2 cache resided on the motherboard, but newer processors have a bit of L1 and L2 cache in the chip package. If you upgrade the cache memory on your computer, you are adding L2 cache to the motherboard — you wouldn’t be able to upgrade the L1 cache on the processor. Because L1 cache is built into the chip, you can’t upgrade it withoou replacing the entire processor. The integration of cache memory into processor chips didn’t come to market until the 80486 chips were developed in 1989. Generally, 80486 chips had 8K of L1 cache, and the Pentium chip increased that amount to 16K. In fact, many newer processors have increased the L1 cache to over 16K and have also included large amounts of L2 cache. The more cache memory a processor has, the quicker (and more expensive) the system will be. Math co-processor The math co-processor, also known as the numeric processing unit (NPU), is the processor’s sidekick. Systems with math co-processors can well outperrfor systems that do not because the math co-processor takes some of the workload off the CPU. For example, it performs many of the large calculaation that applications may require, such as floating point arithmetic. Overall system performance increases because the CPU can focus on logic functions while the math co-processor executes complicated mathematical functions. If you have large spreadsheets or use large graphics applications, you might find that applications run very poorly or not at all on systems without a math co-processor. If you are running a system that does not have a math co-processor integrated into the CPU, you can add one to the motherboard, or perhaps upgrade the main processor.118 Understanding Processor Terminology In earlier computers, the processor was one chip, and the math co-processor was a separate chip on the motherboard. For example, years ago, a 386 computer used an 80386 chip on the motherboard as the processor, but you could add an 80387 chip to the board to act as the math co-processor. All processors since the 80486 computer, including Pentium-class systems, have a math co-processor integrated into the processor’s chip, so you will not be adding a math co-processor to the system. Real-mode versus protected-mode A real-mode processor sees memory as a whole unit and deals with it as a single entity. In other words, if you have 512MB of RAM, the real-mode processor sees that as one block of memory. This is limiting because to run multiple programs at the same time, each program has to be assigned its own independent block of that 512MB — something that real-mode processoor cannot do. As a result, real-mode processors don’t have any multitaskiin capabilities — the capabilities to divide memory into multiple parts and run different applications or tasks in each part. Protected-mode processors support the segregation of system memory into different parts and assigning a different application to each part of memory. Therefore, protected-mode processors support multitasking and multitaskiin operating systems, such as Windows and Linux. Protected-mode processors also support virtual memory, which is the process of using hard disk space as emulated memory. This means you could increase your 512MB of RAM by using 768MB of hard disk space as “pretend” RAM. In this case, as far as the applications that are running are concerned, the system has 1280MB of memory — the combination of true memory plus virtual memory. MMX After the Pentium was developed, Intel introduced a feature called MultiMedia eXtensions, or MMX. MMX added 57 new instructions that were built into the processor and told the system how to work with audio, video, and graphics. If these instructions were not built into the processor, the processor would have to retrieve them from somewhere else. When MMX was developed, both home and business users seemed to be heading toward the world of multimedia, and it made sense to enhance the processor and make it “multimedia aware.” Running any kind of multimedia application on a processor that supports MMX gives you a major performaanc increase over a processor that doesn’t support MMX technology.Book II Chapter 2Picking Your Processor 119 Understanding Processor Terminology Hyperthreading Hyperthreading is a feature designed by Intel that was placed in the Pentium processors. Hyperthreading technology, or HTT, allows a processor to logicaall act as two different processors by being able to execute simultaneous threads. A thread is a part of an application that executes at any given time. For example, when running Microsoft Word, one thread accepts keystrokes, and another thread runs the spell checker while you type. Thus, two parts of the application run at the same time. For a system to truly be able to take advantage of multithreaded applicatioons you normally need a system that has multiple processors — one processor to run one thread at a time. With hyperthreading, one processor can run more than one thread at a time, increasing performance by 15 to 30 percent. Multicore A multicore processor combines a number of independent processors and the L1 cache from those processors onto a single processor chip. The beneffi of a multicore processor is that it can execute multiple threads at the same time without hyperthreading because you essentially have multiple processors in one chip package. A multicore processor has the benefit of having multiple processors’ core features — such as superscalar execution, pipelining, and threading — all packaged into one physical processor. The core features also include each core having its own L1 cache memory. Multicore processors also have a block of shared L2 cache between the two processors in the multicore chip. A huge benefit of being only one chip on the motherboard is that the one multicore chip draws less power than two separate processors would. Figure 2-3 shows the logical view of a dual-core processor. A number of different flavors of multicore processors are available today, such as dual-core, triple-core, and quad-core processors. Here are the differennce between the three: ✦ Dual core: Has two cores in one chip package, with each core typically having 128K of L1 cache and 512K of shared L2 cache. ✦ Triple core: Has three cores in one chip package with each core typicaall having 128K of L1 cache. Most triple-core processors also have 512K of L2 cache per core and share a block of cache memory, known as L3 cache. ✦ Quad core: Has four cores in one chip package with each core typically having 128K of L1 cache. Most quad-core processors also have 512K of L2 cache per core and share a block of L3 cache (2MB–6MB).120 Understanding Processor Terminology Figure 2-3: Looking at the logical structure of a dual-core processor. CPU & L1 Cache CPU & L1 Cache Shared L2 Cache Dual Core Processor Throttling Throttling (a feature built into a lot of newer processors today) involves the CPU sensing when it is going to overheat and then reducing its speed to lower the heat to an acceptable range. Processors that support throttling have a built-in thermal sensor (a high-tech thermometer) that monitors the temperature of the processor. When the processor detects that it is going to overheat — maybe, because of a fan failure — the processor drops its speed so that the temperature drops to an acceptable range. Overclocking Overclocking, a big feature for PC enthusiasts, involves running a piece of hardware faster than the speed at which it is rated. A number of devices can be overclocked, such as video adapters and (of course) processors. Although you might be able to overclock the processor, it is not recommennde because overclocking can result in an unstable system or even hardware failure. VRM The voltage regulator module (VRM) is responsible for regulating the voltage that is delivered to the processor. The VRM is located on the motherboard (or appears as its own device in the system) and provides the correct runniin voltage to the processor.Book II Chapter 2Picking Your Processor 121 Understanding Processor Terminology Some VRMs use a jumper on the motherboard to determine how much voltaag is supplied to the processor, and other VRMs sense what the processor needs on startup. Typically, VRMs on the motherboard sense what voltage the processor needs and then supply that voltage. Chip packaging Chip packaging refers to how the chip is constructed and delivered to the consumer. The chip package defines the appearance or form factor of the chip. Many chip packages have been used over the years. The chip packages you should be familiar with for the A+ exam are as follows: ✦ Dual inline package (DIP) chip: A rectangular chip with two rows of 20 pins. Pin 1 is located at the end of the chip that has a square notch carved into it. It is important to identify pin 1 because when you add a DIP chip to the motherboard, you have to match pin 1 on the chip with pin 1 in the chip socket. Older processors (such as the 8088) and many math co-processor chips use the DIP chip style. Although they are no longer used for CPUs, DIP chips are still used for cache memory and BIOS chips on motherboards. They are also found on memory modules. (See Book II, Chapter 3, for a discussion of memory modules.) ✦ Pin grid array (PGA) chip: One of the most popular processor chip packagge in use today, the PGA chip is a square chip with an array of pins filling up the shape of the chip. In general, the PGA chip uses hundreds of pins. You can locate pin 1 on the PGA by identifying the corner of the PGA chip that has the corner cut off — that corner is where pin 1 is located. Figure 2-4 compares a DIP (right side) with a PGA (left side) chip type. Figure 2-4: Comparing a DIP chip package (right) to a PGA package (left). DIP chip PGA chip Today’s implementation of the PGA chip fits into a zero insertion force (ZIF) socket. The ZIF socket is ideal for upgrading processors (especiaall compared with the days before ZIF sockets were used) because 122 Understanding Processor Terminology the ZIF socket has a lever (on the side of the socket) that you lift to raise the chip from the socket. Because the chip is automatically raised out of the socket, you can simply remove the chip out of the socket with little effort! Before ZIF sockets were used, you had to pry the chip out of the socket while trying to ensure that you did not damage the chip or the pins. With the ZIF socket, after the processor is raised, you can replace the old chip with a new one. In the past, not all boards used ZIF sockets, so you had to get some special extractors to pull the chip out (carefully!). Figure 2-5 shows a ZIF socket. Figure 2-5: A ZIF socket on the motherbooar holds a processor. Socket 7 ZIF socket ✦ Single Edge Contact (SEC) chip: A chip package type that was popular with the Pentium II processors, the SEC chip is a huge cartridge surrouunde by a plastic casing. The newer version, SEC2, is implemented as a card that is inserted into a slot on the motherboard and doesn’t have the big plastic casing around it. It is important to stress that the SEC and SEC2 are inserted into a slot and not a socket. For more informattio on slots and sockets, read the next section. Figure 2-6 shows an SEC chip package along with some PGA chip packages.Book II Chapter 2Picking Your Processor 123 Identifying Socket Types Figure 2-6: An SEC chip package along with some PGA chip packages. SEC chip PGA chips Be sure to remember the different chip package types for the A+ exams. The Pentium II processor used the SEC. Newer processors, such as the Pentium 4, are using the PGA. Identifying Socket Types Intel decided to develop a new standard for upgrading a processor on motherbooards beginning with the 80486 chips and continuing with the Pentiumcllas processors. This standard — a processor socket designed to hold a specific processor chip with the appropriate number of pins — enabled Intel to develop new chips with compatibility of a particular socket in mind. For example, if a socket is developed with 321 pins, Intel could develop a new processor that has 321 pins and know that the processor will work with any motherboard that has the right socket. This allows the consumer to upgrade a processor much easier than in the past. Intel could design a new chip for an old socket so that customers could update their computers by dropping the new processor in the compatible socket.124 Identifying Socket Types Original Pentium processors supported mainly Socket 5 with 320 pins or Socket 7 with 321 pins. Thus, to add a Pentium processor to a motherboard, you determine what socket exists on that board and then purchase a CPU to fit in that socket. You also have to remember to match the voltage of the board to the voltage required by the CPU. Figure 2-7 helps you identify a CPU socket in your system. Sockets are normally labeled by type along the side of the socket. For examplle in Figure 2-7, the socket is labeled as PGA 370, meaning that it is Socket 370 and will hold any processor designed for Socket 370. (Socket 370 is a socket that holds a processor containing 370 pins.) Figure 2-7: Identifying a processor socket. Table 2-1 lists the different types of sockets and the processors that are placed in the sockets. For more information about the processors, read the sections “Looking at Popular Intel Processors” and “Don’t Forget Non-Intel Chips,” later in this chapter. Table 2-1 also shows the number of pins associatte with the different types of sockets and slots. Table 2-1 Processor Socket Types and Slots Socket Processor Number of Pins Socket A Later Athlon, Duron, and Athlon XP 462 Socket 1 80486, 80486DX2, 80486DX4 169 Socket 2 80486, 80486DX2, 80486DX4 238Book II Chapter 2Picking Your Processor 125 Identifying Socket Types Socket Processor Number of Pins Socket 3 80486, 80486DX2, 80486DX4 237 Socket 4 Pentium 60/66 273 Socket 5 Pentium 75-133 320 Socket 7 Pentium 75-200 321 Socket 8 Pentium Pro 387 Socket 370 Celeron and Pentium III 370 Socket 418 Itanium 418 Socket 423 Pentium 4 423 Socket 478 Later Celerons and Pentium 4 478 Socket 603 Xeon (Pentium 4 version) 603 Socket 611 Itanium 611 Socket 940 Opteron 940 Slot A Athlon 242 Slot 1 Pentium II and Pentium III 242 Slot 2 Xeon 330 Socket 754 Turion 64, Athlon 64 , Sempron 754 Socket 775 or LGA775 (also called Socket T) Pentium 4, Pentium D, Celeron D, Core 2 Duo 775 LGA1366 (also called Socket B) Intel Core i7 processor 1366 AM2 Opteron, Sempron, Athlon 64, Athlon 64 X2 940 AM2+ Athlon 64, Athlon 64 X2, Phenom, Phenom II 940 AM3 Phenom II 941 Know the socket types used to hold the Pentium 4, Celeron, Athlon XP, Athlon 64, Phenom, and Turion processors. You will not be expected to memorize the entire Table 2-1, but you should be familiar with the sockets used by today’s popular processors. Originally, the sockets were simply called Socket 1, Socket 2, and so on up to Socket 8. To make it easier to understand what processors went into which sockets, Intel started naming the sockets after the number of pins that existed on the processor that the socket would support. For example, Socket 370 holds a processor with 370 pins, and Socket 478 holds a processso with 478 pins. It is much easier now to identify what processors go into which sockets!126 Looking at Popular Intel Processors Now that you understand some of the characteristics of processors and you understand what a socket is, take a look at some of the popular Intel and AMD chips you are expected to know for the A+ exams. Looking at Popular Intel Processors In this section, I provide an overview of the Pentium-class processors and their characteristics, including data bus, address bus, registers, and the amount of cache memory supported on these processors. You will also be introduced to any new or unique processor features that each processor offers. Pentium The original Pentium processor, released in 1993, was developed at speeds of 60 MHz and 66 MHz. The Pentium processor was a PGA chip that was placed in Socket 5 or Socket 7. Soon after its release, Intel marketed Pentium processors in 75, 90, 100, 120, 133, 150, 166, and 200 MHz flavors, which were really just clock multipliers of the original 60 MHz or 66 MHz systems. Clock multiplying is the concept that the processor will run faster than the motherboard that the processor sits in. For example, the original Pentium processor ran on 60 or 66 MHz motherboards. Say that the computer is marketed as a Pentium 90. Because you know that the motherboard runs at 60 or 66 MHz, you can determine that the 90 comes from 60 × 1.5 — meaning that the processor runs 1.5 times the speed of the motherboard. This is important because as a consumer, when you purchase a computer, you want to make sure you know what the motherboard speed is, too — not just the advertised speed of the processor. From a consumer’s point of view, clock multipliers become important when you take a look at computers such as the Pentium 133 and the Pentium 150. Which is faster? The obvious answer is the Pentium 150, the system with the higher megahertz speed. But is it really? The Pentium 133 is a clock double of the 66 MHz board, and the Pentium 150 is a clock double and a half of the 60 MHz board. My point being that the overall performance of the system is controlled by more than just the speed of the processor — you need to consiide other components, such as the speed of the motherboard. By looking at the motherboard speeds of the Pentium 133 and the Pentium 150, you could assume that the computer running the Pentium 133 might be able to keep up with (if not outperform) the one running the Pentium 150. Table 2-2 compares the speed of the motherboard and processor for the differren Pentium systems.Book II Chapter 2Picking Your Processor 127 Looking at Popular Intel Processors Table 2-2 Pentium Clock Multipliers Processor Motherboard Speed (MHz) Multiplier Processor Speed (MHz) Pentium 90 60 1.5 90 Pentium 100 66 1.5 99 Pentium 120 60 2 120 Pentium 133 66 2 132 Pentium 150 60 2.5 150 Pentium 180 60 3 180 Pentium 200 66 3 198 Pentium II 100 4.5 450 The Pentium processor has a 32-bit address bus, 32-bit registers, and a 64-bit data bus. It also has 16K of L1 cache that is divided into two 8K channels. One channel is for data cache and the other for application code cache. Before the Pentium came along, processors used one instruction pipeline. This meant that when an application executed, it would run each stage of the application job one step after the other. For example, if an application has three lines of code, as seen in Figure 2-8, each line of code can be processse only after the previous line of code is fully completed. This creates a delay, or wait time, which slows performance. Figure 2-8: Singleinstrructio pipelined processor executing application code. 80486 CPU Program Code Instruction Pipeline strFirstName= "Glen" strLastName= "Clarke" strFullName= strFirstName & " " & strLastName The Pentium processor introduced a feature called superscalar design. The processor has two instruction pipelines, named U and V. Having two instruction pipelines enables the processor to execute two instructions at the same time. Thus, the three lines of program code, shown in 128 Looking at Popular Intel Processors Figure 2-9, can be quickly executed on a Pentium processor because lines 1 and 2 are processed at the same time, causing line 3 to be processed that much sooner. Notice that lines 1 and 2 execute parallel to one another; therefore, parallel processing is taking place. Figure 2-9: Dualinstrructio pipelined processor processing application code. Pentium CPU Program Code v u Instruction Pipelines strFirstName= "Glen" strLastName= "Clarke" strFullName= strFirstName & " " & strLastName An application has to be designed to take advantage of two instruction pipelinnes These applications are often labeled something like Pentium Aware or Pentium Ready. Pentium Pro In 1995, Intel released the Pentium Pro chip, which added a new level of performance to the Pentium processor. The Pentium Pro had all the characterristic of the Pentium processor — such as a 64-bit data bus and 32-bit registers — but it increased the address bus to 36 bits, which means that the Pentium Pro could access 64GB of RAM. The speed of the Pentium Pro ranges from 120 MHz to around 200 MHz. The Pentium Pro included two additional features on its chip that helped it outperform the original Pentium. First, the Pentium Pro chip is really a twochhi team. One chip was the actual processor (with 16K of L1 cache, like the Pentium chip), but the other chip holds an extra 256K of cache memory. Because this cache memory is physically outside of the CPU, it is considerre L2 cache. The second feature that led to the performance gain of the Pentium Pro is dynamic execution, which has three stages: multiple branch prediction, datafllo analysis, and speculative execution. ✦ Multiple branch prediction is the idea that the processor will look ahead and predict a number of instructions that might be needed in the very near future.Book II Chapter 2Picking Your Processor 129 Looking at Popular Intel Processors ✦ Dataflow analysis occurs when the processor looks at the instructions it has predicted will be needed next and then assigns them a logical order of execution. ✦ Speculative execution is the actual execution of a given instruction based on the prediction and the order of execution assigned. The Pentium Pro chip, shown in Figure 2-10, was implemented as a PGA chip that was placed in Socket 8. Figure 2-10: The Intel Pentium Pro processor. Pentium II In 1997, Intel produced the Pentium II, which was really just an enhanced Pentium Pro with speeds ranging from 233 MHz to 450 MHz. The Pentium II had a 64-bit data bus, a 36-bit address bus (64GB of RAM), and 32-bit registeers and supported features such as MMX. The Pentium II increased the amount of L1 cache that was integrated into the CPU to 32K, as opposed to 16K. The 32K of L1 cache was still divided into two equal channels: one 16K channel for data and one 16K channel for application code. Intel packaged the Pentium II in the Single Edge Contact (SEC) — sometimes also referred to as the Single Edge Contact Connector (SECC) — that fits into Slot 1 on the motherboard. The SEC is a module enclosed in a casing or shell with two chips inside: one chip being the processor, and the other chip being the 512K of L2 cache. Refer to Figure 2-9 to see what a Pentium II processor, which uses the SEC, looks like. Another enhancement that accompanied the Pentium II was single instructiio multiple data (SIMD). To visualize how SIMD works, imagine five toddller in a playroom, and that these toddlers are at the entertaining age of 130 Looking at Popular Intel Processors two — the age, of course, when the toddlers are preparing for their teen years by answering “no” to everything you say. You walk into the playroom and see that the five toddlers have found your box of darts and are throwiin them at the walls. You are faced with a choice: You can either walk around to each child and explain why throwing darts at your walls is not a good idea (which means you will have to explain the same thing five differeen times), or you can have a good scream at the top of your lungs, which means that all the children will stop immediately and listen. SIMD works on the same basic principle. With SIMD, the processor gives the instruction to multiple processes at once instead of having to give the same instruction multiple times. Thus, the processor saves time and creates a much more efficient way to work with information. Celeron The Pentium II processor performed very well, and with all that cache memory, it should! Unfortunately, that performance came with a price. If you were not willing to pay that price, Intel created a chip for you: the Celeron chip! The Celeron chip is nothing more than a less-expensive version of the Pentium II processor with the built-in L2 cache either removed entirely or reduced. The first-generation Celeron chip was code-named the Covington; it has no L2 cache memory on it. The second-generation Celeron was codenaame the Mendocino, and it contains 128K of L2 cache. Although this versiio of the Celeron does have L2 cache, it is dramatically reduced from the Pentium II’s 512K so that it can be sold at a lower price. The original Celeron shipped in an SEC package but also had a version that was packaged as a PGA, as shown in Figure 2-11. Figure 2-11: Intel’s Celeron processor was first implemennte as an SEC package, but later had a PGA chip that was placed in Socket 370. Book II Chapter 2Picking Your Processor 131 Looking at Popular Intel Processors Pentium III The Pentium III processor shares many of the Pentium II characteristics. It supports dynamic execution (as the Pentium Pro also did) and MMX technollogy has 32K of L1 cache, and has either 256K or 512K of L2 cache. The Pentium III runs at a speed of 450 MHz to 1000 MHz (1 GHz). The Pentium III chip offers 70 additional instructions that are integrated into the chip, enhancing the user’s experience with 3-D graphic applications. The Pentium III chip also supports a number of low-power states to help conseerv energy when the system is not in use. This processor is designed to run on either 100 MHz or 133 MHz motherboards. Also note that there is a Pentium III version of the Celeron chip that runs as fast as the Pentium III processor but again has the L2 cache memory reduced. So now there are multiple versions of the Celeron chip — the PII version and the PIII version. The Pentium III processor shipped in the SEC2 package (as shown in Figure 2-12) originally, but was then packaged as a PGA chip. The SEC2 goes in Slot 1, and the PGA chip is inserted into Socket 370. Figure 2-12: The Pentium III processor in the SEC2 package that lives in Slot 1. Xeon The Xeon processor is built on the Pentium II and Pentium III architecture — meaning that, like the Celeron, there is a PII version and PIII version of the Xeon. The Xeon chip is designed for higher-end systems, such as servercllas systems, and contains more cache memory than the typical PII and PIII. The Xeon comes in flavors of 512K, 1MB, and 2MB of L2 cache.132 Looking at Popular Intel Processors The Xeon can also address 64GB of RAM and is designed for multiprocessiin systems: that is, computers with a motherboard that supports multiple CPUs. The Xeon processor has been designed to coexist with two, four, or eight CPUs. The Pentium II Xeon and Pentium III Xeon chips were originally packaged as an SEC (as shown in Figure 2-13) that was placed in Slot 2, but later versions use the PGA and are placed in Socket 603. The Xeon chip also contains a thermal sensor that shuts the processor down if it starts to overheat. Figure 2-13: The Pentium II Xeon processor was originally delivered in the SEC package. The Celeron is a scaled-down version of the Pentium II or III processor, and the Xeon is a step up from the Pentium II or III. There are also PIV (Pentium 4) versions of the processors: ✦ PIV Xeon: Designed to work with a multiprocessing system that uses one or two processors ✦ PIV Xeon MP: Designed to work with a multiprocessing system that uses four or eight processors Pentiu m 4 The Pentium 4 processor runs between 2 GHz and 4 GHz. The Pentium processso has 20K of L1 cache and 512K of L2 cache. The processor is shipped as a 423-pin or 478-pin PGA package, which means that the chip will be placed in Socket 423 or Socket 478 (as shown in Figure 2-14).Book II Chapter 2Picking Your Processor 133 Looking at Popular Intel Processors Figure 2-14: Socket 478 can house a Pentium 4 processor. The Pentium 4 processor gets a huge performance benefit by being able to perform four data transfers in one clock cycle along the front side bus (FSB), which is the bus that connects the processor to system memory. (See Chapter 1 of this minibook.) Most Pentium 4 processors today are multicore processors and enjoy the performance benefits that multicore brings. Itanium and Itanium II Intel created its first 64-bit processor in the Itanium and Itanium II processoor and was marketed for server class–system or high-end PCs. Although the Itanium is a 64-bit processor and designed to run 64-bit software such as the 64-bit version of Windows, the Itanium can run some 32-bit code with the use of an emulator, but the code will run slower than if it were on a 32-bit processor. Special 64-bit editions of Windows can run on the Itanium processor, which enables you to take advantage of the 64-bit architecture. To learn more about the 64-bit editions of Windows, check out www.microsoft.com/windowsxp/64bit/default.mspx134 Looking at Popular Intel Processors The original Itanium processor used a special packaging known as the pin array cartridge (PAC), which uses 418 pins. The Itanium II was packaged in organic land grid array (OLGA) — a variation of the PGA — but the chip is located on a processor card (a circuit board that holds the processor). The OLGA fits into Socket 611. The Itanium processor runs at around 1 GHz and contains a large block of cache memory: 32K of L1 cache, 96K of L2 cache, and 2MB or 4MB of L3 cache. The L3 cache is an additional block of cache memory located in the chip packaging. Moving from 32-bit processors and applications to 64-bit versions would truly benefit any user using applications that are memory intensive or calculattio intensive. For example, a user who works a lot with multimedia-type applications would see an improvement in performance. Pentium M For years, laptop manufacturers have been asking for smaller processors to place in laptop systems, and they finally have their wish. A number of processors have come out with the M version, which stands for mobile. The mobile versions of the processors are smaller than the processors that go in desktop systems, so they fit better and also use a lot less power. The benefit of using less power also means that they run much cooler. Because the mobile versions of the processors use less power, they also run a little slower than their desktop counterparts. Some popular brands of mobile processors are the Intel Pentium III M and the Pentium M. Intel’s big competitor, AMD, also has mobile versions of their processors: Athlon XP M and Mobile Duron. (Some manufacturers put the word mobile in the name of the processor instead of the letter M.) The next sections discuss more about AMD processors. Intel Core 2 Intel designed the Intel Core 2 to be its 64-bit, multicore processor. The Core 2 comes in three flavors: ✦ Core 2 Solo: Single-core processor ✦ Core 2 Duo: Dual-core processor on the one chip ✦ Core 2 Quad: Actually two chips, with two cores per chip, packaged in a multichip module Core 2 processors range in speed from 1 GHz to around 3 GHz and fit into an LGA 775 socket, also known as Socket T. Core 2 processors come with either 2MB of L2 cache or 4MB of L2 cache.Book II Chapter 2Picking Your Processor 135 Don’t Forget Non-Intel Chips Intel Atom Intel has created a processor to run on the now-popular Netbooks. A Netbook is a laptop-like computer — but much smaller — that is used primarily for Internet usage. The Netbook is much smaller and cheaper than a regular laptop system and is marketed for e-mail and Web browsing features. The Intel Atom has many characteristics of normal processors — it runs between 1 GHz and 2 GHz and contains 32K of L1 cache and 512K of L2 cache. Originally the Atom processor had one instruction pipeline, but there are versions with two instruction pipelines. There are also single core and dual core versions of the Atom processor. Don’t Forget Non-Intel Chips One of Intel’s major competitors is Advanced Micro Devices (AMD). AMD has developed a family of processors that compete with Pentium-class processsors In this section, I provide an overview of some of the characteristics of the AMD processors. K6 The AMD K6 processor was designed to compete with the original Intel Pentium. The K6 has 64K of L1 cache, supports MMX technology, and has built-in branch prediction techniques. This processor has 321 pins, which means that it will fit into a Socket 7–supported motherboard. K6-2 The K6-2 processor was designed to compete with the Pentium II chip. It has 64K of L1 cache and 256K of L2 cache. The K6-2 also supports dynamic execution, MMX technology, and superscalar design. The K6-2 has added 3DNow! technology, comprising a number of additional instructions integrated into the chip to improve 3-D graphics applicatioons The K6-2 chip also uses a 100 MHz motherboard speed, which is a big improvement over the 60/66 MHz motherboard speed that the original Pentiums used. The K6-2 has 321 pins, which means that it will fit into a Socket 7–supported motherboard. K6-III The K6-III processor is designed to compete with the Pentium III chip. This chip shares many of the features of the K6-2, including a 100 MHz system bus. One of its features was the tri-level cache. Not only can it take 136 Don’t Forget Non-Intel Chips advantage of an L1 and L2 cache but also an L3 cache that can be included on the motherboard. Athlon The AMD Athlon chip has 128K of L1 cache and 512K of L2 cache. It supports improved dynamic execution, MMX technology, and 3DNow! technology. The Athlon chip runs at speeds of up to 1.2 GHz and is designed to run on a 200 MHz system bus speed. Unlike the K6-2 and K6-III, the Athlon is not a PGA-packaged chip that suppoort Socket 7. It uses its own socket type — Slot A, so called because the processor is packaged as an SEC. The Slot A socket is not compatible with Intel’s Slot 1, which means that users have to purchase a motherboard designed for the Athlon chip. Later versions of the Athlon moved to the PGA package that has 462 pins. These PGA chips are placed in Socket A. Athlon XP After the Athlon chip was produced, Intel created the Pentium 4 chip. So AMD wanted to create a competing chip for the Pentium 4: namely, the Athlon XP. The Athlon XP is packaged as a PGA with 462 pins and is placed in Socket A. The Athlon XP runs at 2 GHz or more and contains 128K of L1 cache and 512K of L2 cache. AMD markets these processors a little differently. Instead of labeling the processor with its speed, AMD labels it with its competitor’s speed. For example, the Athlon XP 1800+ is rated at 1.6 GHz but runs as fast as the Intel 1.8 GHz processor. Duron AMD wanted to create a processor that competed with each version of the Intel processors. So, if the Athlon XP competes with the Pentium 4, what competes with the Celeron? You guessed it — the Duron. The Duron has 128K of L1 cache and 64K of L2 cache. This processor is packaged as a PGA with 462 pins, which means that it, too, goes into Socket A. Opteron Just like the Duron was built to compete with the Intel Celeron, AMD created the Opteron to compete with Intel 64-bit Itanium processors. The Opteron runs at about 1.8 GHz and contains 128K of L1 cache and 1MB of L2 cache.Book II Chapter 2Picking Your Processor 137 Don’t Forget Non-Intel Chips The Opteron is packaged with a micro-PGA, which is made up of 940 pins and is placed in Socket 940. One of the major differences between the Opteron and the Itanium is that the Itanium cannot run 32-bit applications. AMD decided that the Opteron would run in a 32-bit or 64-bit mode, thus allowing it to run 32-bit applications. Athlon 64 and Athlon 64 X2 The Athlon 64 — the successor to the Athlon XP — is the AMD 64-bit processso for desktop systems. The Athlon 64, with 128K of L1 cache and at least 512K of L2 cache built into the processor, is designed to compete with the Pentium 4. Although the Athlon 64 is a 64-bit processor, it has been designed to be backward compatible; it can run 32-bit code. The Athlon 64 X2 is the dualcoor version of the Athlon 64. The Athlon 64 family processors fit into a number of sockets: Socket 754, Socket 940, and the AM2 socket. Know that the Sempron processor is a low-end version of the Athlon 64 and has replaced the Duron as the AMD low-end processor. The Sempron was originally a 32-bit processor with reduced cache size, but current versions are 64-bit with the cache size reduced. Phenom and Phenom II The Phenom and Phenom II pick up after the Athlon 64 and are the AMD triple-and quad-core processors. The Phenom, designed for desktop systeems uses the code names Toliman for the triple-core version and Agena for the quad-core version. The Phenom processor, which comes with 128K of L1 cache and 512KB of L2 cache per core, also has 2MB of shared L3 cache. The processor fits in the AMD AM2+ socket and runs between approximately 1.8 GHz and 2.6 GHz. The Phenom II also sits in the AM2+ socket and increases the shared L3 cache to 6MB! There were issues with the Phenom running on Windows Vista, but those bugs have been fixed for the Phenom II. The Phenom II has a triple-core version, code-named Heka, that runs between 2.6 GHz and 2.8 GHz. The quad-core version that is named Deneb runs between 2.5 GHz and 3.0 GHz. Turion 64 and Turion 64 X2 The Turion 64 processor is the AMD 64-bit mobile processor for use in laptop computers. The Turion processor used to be called the Athlon Mobile 64, but AMD has moved to the new label of Turion 64 for its mobile processors. The Turion 64 is a single-core processor, and the Turion 64 X2 is the dual-core processor.138 Installing a Processor Turion 64 processors come with 128K of L1 cache and either 512K or 1024K of L2 cache. Both the Turion 64 and the Turion 64 X2 fit into Socket 754, and the newer chips fit in AMD Socket S7. Be sure to know the multicore processors for the exam. The Athlon 64 X2 is the AMD dual-core processor, and the Phenom/Phenom II have triple-core and quad-core versions. Also be familiar with the Turion being the AMD 64-bit processor for laptop computers. Installing a Processor Now that you understand some of the popular processors that exist today, take a look at how to install a processor. This section identifies installation decisions you have to be aware of before actually attempting to install the processor. Will it fit in the socket? The first thing you need to verify before you purchase a new processor for your system is what socket type you have on your motherboard. You want to make sure that you purchase a processor that fits in that socket. For example, if you have Socket A on the motherboard, what processors fit in Socket A? If you said Athlon, Athlon XP, and Duron, you are correct. Also be sure you know how many pins the socket has because some processoor support a few differently sized sockets. For example, Intel makes both Socket 423 and Socket 478 versions of the Pentium 4, so make sure you get the correct version of the Pentium 4 for your socket. CPU voltage and transistor integrationAnother important CPU characteristic that you have to watch for when upgrading your processor is the voltage the processor requires. Voltage is the power that the processor draws from the main motherboard, which the motherboard receives originally from the power supply. A processor is designed to run at a certain voltage. You need to ensure that the motherboard you are placing the processor into provides that voltage. If a motherboard supports more than one voltage, you can typically change a jumper on the motherboard, which will then control the voltage used by the processor. For more information on jumpers, check out Book II, Chapter 1.Book II Chapter 2Picking Your Processor 139 Installing a Processor Performing the installation Because most systems today use ZIF sockets and PGA chips, I discuss installing a processor into the ZIF socket. After you verify that your new processor will work with your motherboard, you are ready to install the processor. To install the processor, first remove the existing one by pulling up on the lever on the ZIF socket. When you pull the lever on the ZIF socket, the existing processor should rise out of the socket a bit. Be sure to ground yourself before touching the insides of a computer. Get an antistatic wrist strap and clamp it to the computer’s chassis so that you have a constant ground. For more information on safety procedures, read Book I, Chapter 3. With the processor a bit out of the socket, you can then gently lift out the processor (as shown in Figure 2-15). Be sure to lift the processor straight up so that you do not bend any of the pins. Figure 2-15: Removing the processor from its socket. 140 Installing a Processor After you have the old processor out of the socket, you can install the new processor by first finding out where pin 1 is on the processor chip. Pin 1 is located in one of the corners of the chip and is usually indicated with a gold line marked on the bottom of the chip that contains the pins. If you do not see a line indicating where pin 1 is, you will notice that one of the corners of the square PGA is cut off (see Figure 2-16) — this corner is pin 1. Figure 2-16: The cutoou corner of the processor indicates the location of pin 1. Pin 1 indicator After you locate pin 1 on the PGA chip, you also need to figure out where pin 1 goes in the socket. Again, you can figure this out by finding the cut-off corner of the socket. This corner is where the cut-off corner of the processso goes, as seen in Figure 2-17. After you match up pin 1 on the PGA chip with pin 1 on the ZIF socket, carefuull place the processor into the socket and then push the lever down to lock it in place. Just lay the chip into the socket; don’t push it in. The whole point of a zero insertion force socket is that you don’t have to risk damaging the pins by applying pressure.Book II Chapter 2Picking Your Processor 141 Keeping a Processor Cool Figure 2-17: Identifying the cut-out corner in the processor socket. Pin 1 indicator Keeping a Processor Cool After you have the processor in the processor socket, you need to install something to keep it cool, such as a heat sink or fan — or maybe even both. Processors are made up of thousands, even millions, of transistors. A transistor acts as a switch, permitting or prohibiting the flow of electrical current. If current is allowed to flow through the transistor, some result is generated. If the current is not allowed to flow through the transistor, a differren result is generated.142 Keeping a Processor Cool A processor contains millions of transistors that each hold an electrical charge, causing the processor to run at very high temperatures. Therefore, it is important to keep the processor cool. The most common cooling mechanisms today are heat sinks and CPU fans, which are sometimes used in tandem. A number of other cooling devices are on the market today, and they are a little more expensive than your typical heat sink or CPU fan. The following are other cooling techniques you may find in systems today: ✦ Liquid cooling: A liquid cooling system pumps a cooling liquid throughoou the PC by using small hoses. The benefit of a liquid cooling system is the reduced noise, but its big drawback is the amount of space needed in the PC for the components of the cooling system — and, of course, the threat of a leak if the cooling system is not installed properly. ✦ Temperature sensors: A number of processors today come with a builtii thermal sensor (a high-tech thermometer). Temperature sensors allow the processor to identify that it is overheating and then shut itself down until the temperature drops to normal. ✦ Thermal compound: This liquid paste is placed between the processor and the heat sink to help draw the heat away from the processor and pass it through the heat sink. ✦ Heat pipes: A heat pipe is designed to transfer heat from a hot temperaatur source by vaporizing a form of coolant liquid that is then vacuumed away from the heat source to a cooler interface. The vapor can then be rerouted from the cool source to the heat source again as a liquid to perform the cooling process again. Heat sinks and CPU fans Because of the size of the Pentium processor and the number of transistors passing current, the chip can get so hot that it becomes unstable. Thus, many Pentium processors come with either a cooling fan or heat sinks. A number of processors today have a heat sink with a fan on top of the heat sink. Heat sinks are a group of metal pins placed on the chip to draw heat away from it. A cooling fan is a small fan placed on top of the processor to pull away hot air, helping to keep the processor cool. Figure 2-18 shows a heat sink. Installing a heat sink and fan Some processors can get so hot that a heat sink might not be enough of a cooling device; in this case, you might want to place a fan on top of the heat sink. To install the heat sink and fan on your system, simply place the heat sink on the processor and then clamp it in place with the heat sink–clamping bar. After you have the heat sink in place, you can secure a fan on top of it by clamping the fan on the heat sink, as shown in Figure 2-19.Book II Chapter 2Picking Your Processor 143 Keeping a Processor Cool Figure 2-18: Looking at a heat sink. Figure 2-19: Placing the fan on top of the heat sink. The term passive heat sink is used for a heat sink that does not use a fan on top, and the term active heat sink is used for a heat sink with a fan on top.144 Increasing Performance Increasing Performance When it comes to processors, there are a number of different ways to increase the performance of your system. A first and obvious way is to buy the faster processor when upgrading; for example, upgrade a 1.8 GHz processor to a 3 GHz processor if possible. Also, get a processor designed to run on the faster motherboards. For example, back when Pentium II processors were popular, there were 100 MHz motherboards or 133 MHz motherboards. You get a faster system by having a 133 MHz motherboard. You will have to look at other features of the processor, such as the L1 cache and L2 cache that reside in the processor packaging. Acquiring a processor with more cache memory can dramatically increase system performance. Getting an A+ This chapter provides an overview of the key terms that are used to identify the popular processors and their capabilities. Some of the points you need to remember when preparing for the exam are ✦ Chip packages: The three major chip packages are DIP, PGA, and SEC. PGA is the popular chip packaging used in today’s systems. ✦ Processor speed: Processor speed is measured in gigahertz (GHz) but was measured in megahertz (MHz) in the past. ✦ Cache memory: L1 cache is cache memory integrated into the processor chip, while L2 and L3 cache are found outside the CPU chip. ✦ Sockets: A socket is used to hold the processor in place on the motherboaard Be sure to be familiar with the sockets for the Intel Pentium III, Pentium 4, and Celeron chips. Also know about the sockets for the AMD Athlon, Athlon XP, and Duron chips. ✦ Chips: Be sure to review the characteristics of different Intel chips and AMD chips.Picking Your Processor Prep Test 1 Which of the following best describes superscalar design? A ❍ The processor is designed using only 3.1 transistors. B ❍ The processor predicts the next few instructions to be executed and then determines the optimal order for the execution of these instructions. C ❍ The processor has two instruction pipelines, which enables multiple instructions to execute at the same time. D ❍ The processor works twice as fast as the motherboard. 2 In what socket/slot would you find a Pentium II processor? A ❍ Socket 5 B ❍ Socket 1 C ❍ Socket 7 D ❍ Slot 1 3 Which of the following are placed in Socket A? (Select all that apply.) A ❏ Pentium III B ❏ Athlon XP C ❏ Celeron D ❏ Pentium 4 E ❏ Duron F ❏ Itanium 4 What chip type was the original Pentium processor packaged in? A ❍ SEC B ❍ PGA C ❍ DIP D ❍ Socket 5 5 Which of the following is a characteristic of protected-mode processors? A ❍ Heat sink support B ❍ Virtual memory support C ❍ Run only one application at a time D ❍ Encased in protective shellPicking Your Processor 6 How much L1 cache does a Pentium III processor have built in? A ❍ 32K B ❍ 64K C ❍ 8K D ❍ 16K 7 Which of the following acts as a storage container for information that will be processed by the processor? A ❍ Data bus B ❍ Address bus C ❍ Registers D ❍ Math co-processor 8 How much memory can a Pentium Pro address? A ❍ 128MB B ❍ 512MB C ❍ 4GB D ❍ 64GB 9 Which statement best describes the purpose of a math co-processor? A ❍ Performs all logic functions on behalf of the processor B ❍ Performs floating-point calculations on behalf of the processor C ❍ Runs all applications, and a processor runs the operating system in a multitaaskin environment D ❍ Allows for communication between devices 10 Which sockets/slots do original Pentium chips typically fit into? (Choose two.) A ❏ Socket 1 B ❏ Socket 5 C ❏ Slot 1 D ❏ Socket 7 11 How much L1 cache memory does a Pentium II have built in? A ❍ 8K B ❍ 16K C ❍ 32K D ❍ 64KPicking Your Processor 12 What sockets do Pentium 4 processors fit into? (Choose two.) A ❏ Socket 370 B ❏ Socket 423 C ❏ Socket 478 D ❏ Socket 920 13 What is the major difference between a Celeron processor and a Pentium 4 processor? A ❍ The Celeron has more L1 cache memory. B ❍ The Celeron has less L1 cache memory. C ❍ The Celeron has more L2 cache memory. D ❍ The Celeron has less L2 cache memory. 14 Which of the following CPU characteristics determines how much total memory the system can access? A ❍ Data bus B ❍ Address bus C ❍ Registers D ❍ Math co-processor 15 In what chip package type was the Pentium II processor packaged? A ❍ Slot 1 B ❍ PGA C ❍ DIP D ❍ SEC 16 Which processor is the AMD 64-bit processor designed for laptop systems? A ❍ Core 2 B ❍ Athlon 64 C ❍ Phenom II D ❍ Turion 64 17 What chip type uses a ZIF socket? A ❍ SEC B ❍ DIP C ❍ PGA D ❍ Socket 5Picking Your Processor 18 What is the name of the Intel processor that has four cores? A ❍ Intel 64 X2 B ❍ Intel 64 X4 C ❍ Intel Core 2 Quad D ❍ Intel Core 2 Duo 19 A Pentium 133 runs on what speed motherboard? A ❍ 60 MHz B ❍ 66 MHz C ❍ 100 MHz D ❍ 133 MHz 20 What type of cache is integrated into the Pentium processor’s chip? A ❍ L1 cache B ❍ L2 cache C ❍ Integrated cache D ❍ DRAM cachePicking Your Processor Answers 1 C. Superscalar design is the idea that the processor has more than one instructiio pipeline to process application code. Choice B describes a feature called dynamic execution, and choice D describes a clock double chip. See “Pentium.” 2 D. The Pentium II chip comes in a package called the Single Edge Contact (SEC) chip package, which fits into Slot 1. Sockets 5 and 7 are used by original Pentiums, and Socket 1 is used by some 80486 chips. Review “Pentium II.” 3 B, E. AMD Athlon, Athlon XP, and the Duron chip are placed in Socket A. Check out “Don’t Forget Non-Intel Chips.” 4 B. The original Pentium processor was packaged in the pin grid array (PGA) chip type, which fits into either Socket 5 or Socket 7. Socket 5 and Socket 7 are incorreec choices because they are not chip types; they are the names of sockets. Dual inline package (DIP) is an older type of packaging for processor chips, and SEC is the chip packaging used with Pentium II processors. Peruse “Pentium.” 5 B. Virtual memory is one of the features of protected-mode processors. Choice C describes real-mode processors, the opposite of protected-mode processors. Take a look at “Real-mode versus protected-mode.” 6 A. The Pentium III processor contains 32K of L1 cache. Peek at “Pentium III.” 7 C. Registers are storage areas for information to be processed by the processor. The data bus is the pathway to system memory, the address bus controls how much memory can be recognized by the processor, and the math co-processor performs many of the complicated mathematical operations. Look over “Registers.” 8 D. The Pentium Pro has a 36-bit address bus, which enables it to access 64GB of system memory. The original Pentium processor could address up to 4GB of system memory. Study “Pentium Pro.” 9 B. The math co-processor performs many of the complicated math operations on behalf of the CPU, and the CPU itself performs the logic functions. Refer to “Math co-processor.” 10 B, D. The Pentium processor is placed into either Socket 5 or Socket 7. Pentium II uses Slot 1, and some 486 chips use Socket 1. Examine “Pentium.” 11 C. The Pentium II chip increased the L1 cache to 32K, which is broken into two 16K channels. One channel is used for application code, and one is used for data. 486 chips originally used 8K, and Pentium chips originally used 16K. See “Pentium II.” 12 B, C. Pentium 4 processors have either 423 or 478 pins, so they are placed in either Socket 423 or Socket 478. Review “Pentium 4.”Picking Your Processor 13 D. The Celeron chip is a cut-price Pentium chip. The L2 cache is decreased to save on cost. Celeron chips either have no L2 cache or 128K cache, and Pentium II, Pentium III, and Pentium 4 chips have 512K of L2 cache. Check out “Celeron.” 14 B. The address bus dictates how much memory the CPU can address. The data bus is the pathway to system memory, and registers are storage areas for data being processed. Peruse “Address bus.” 15 D. The single edge connector (SEC) was used for Pentium II processors. Slot 1 is not a chip package type, but a slot that holds the SEC. Newer processors now use the PGA format. Although DIP chips are no longer used for processors, it is still important to understand what the DIP chip looks like because most BIOS chips come in that format. Take a look at “Chip packaging.” 16 D. The Turion 64 is the AMD 64-bit mobile processor to be used on laptop systeems Peek at “Turion 64 and Turion 64 X2.” 17 C. PGA packaged chips can be placed in ZIF sockets. These sockets have a lever; when the lever is pulled, the processor chip pops out of the socket. Look over “Chip packaging.” 18 C. The Intel Core 2 Quad is the Intel processor with four cores. It is made up of two chips, with each chip having two cores. Study “Intel Core 2.” 19 B. The Pentium 133 is a clock-double processor. It runs twice as fast as the motherboard. Therefore, the motherboard speed is 66 MHz. Refer to “Pentium.” 20 A. L1 cache is integrated into the processor, and L2 cache typically has always resided outside the CPU, usually on the motherboard. DRAM is a type of memory used for RAM. It is not used for cache memory. Examine “Cache memory.”Chapter 3: What to Remember about Memory Exam Objectives ✓ Understanding memory terminology ✓ Identifying RAM types ✓ Understanding DRAM types ✓ Working with memory modules ✓ Identifying parity and nonparity memory Finding out how much memory a computer has is one popular way to measure that computer’s power and capabilities. Think about it: If someone asked you what kind of computer you have, what would you answer? Probably something like, “I have a Pentium 4 with 1 gig of RAM.” But why do we measure the power of a computer based on the amount of memory it has? In this chapter, you discover the purpose of memory and some of the different types of memory found in computers today. This chapter also discusses issues that affect installing memory in personal computers and laptops. Understanding the Types of Memory This section outlines different types of computer memory — anything that stores information either permanently or temporarily. Computers have two different flavors of memory: ROM and RAM. From an exam perspective, make sure you fully understand the different types of memory and their uses because you are sure to see a few questions on memory.152 Understanding the Types of Memory Remembering the purpose of memory Before you look at the different types of memory, you need to understand the purpose of memory. Think about your desk at home or in the office. Whether sitting at your home or office desk (working on a proposal or preparing for your A+ Certification exam), chances are good that your desk is covered with documents, books, and papers. This desk is your work area, and its size dictates how many documents you can work on at any given time. System memory works the same way. You have documents and applications stored on the hard drive. When you want to work on these documents, you open them and place them in the computer’s work area. The work area (or desk space) for a computer is system memory. When you want to work with any application or document, the computer must retrieve that information from the hard drive and execute it from memory. Assume, for instance, that your computer has 512MB of memory (not a lot in this day and age). You start up your system, which is running Windows XP, and decide to run Microsoft Word and Adobe Photoshop at the same time. Assume that you open two very large files in each application. Assume further that you are using 480MB of precious memory at this point — a few MBs for the operating system (OS) to load, and a few for each running application. As you can see, your memory usage adds up quickly. In this scenario, you are already using 480MB of memory, which leaves a scant 32MB of memory remaining. Assume that you are about to open up a Photoshop document and copy and paste information from one file to another. To put it simply, you are running out of desk space. You can solve the problem in one of two ways: ✦ Do less work. In other words, work in one application at a time. This is not an optimal solution, especially for business users who often need to run multiple applications simultaneously. ✦ Get a bigger desk. In computer terminology, install more RAM. When you install more RAM, you have a bigger desk to work on. Now that you understand the general purpose of memory, it’s time to dive into the different types of memory. For the A+ exam, you are required to know many different types of memory, which I outline in the following sections. Read-only memory (ROM) ROM is a type of memory that you cannot write to: hence its name, readonnl memory. Information is written to ROM chips by the manufacturer, and this information cannot be changed. In the past, if ROM information needed Book II Chapter 3What to Remember about Memory 153 Understanding the Types of Memory to be updated, you had to remove the original ROM chip and replace it with an updated ROM chip from the manufacturer. Today, you can update the ROM by running a special software program downloaded from the manufacturer’s Web site. In essence, you do not really have a ROM chip but rather have an EEPROM (more on EEPROM in a bit). Software written to a ROM chip is firmware. One of the major uses for ROM is storing the system BIOS (Basic Input-Output System), which contains Power-on Self-Test (POST) routines and other routines that initiate loading the OS. The BIOS also contains the lowleeve code that allows the system to communicate with hardware devices. You need to know that the POST is part of the BIOS code stored in ROM. The POST contains routines that initiate OS loading as well as routines that make communication between hardware devices possible. EPROM EPROM (erasable programmable ROM) is a type of memory that normally cannot be written to because it is a variation of ROM. An EPROM chip is a special ROM chip that the manufacturer can reprogram by using a special programming device that uses ultraviolet light. EEPROM A newer implementation of ROM is electrically erasable programmable ROM (EEPROM), or flash ROM. The manufacturer writes the software instructions into the ROM chip, but you can update these instructions by running a special software setup program provided by the manufacturer. The software setup program is usually available through the manufacturer’s Web site. EEPROM (better known as flash ROM) is a ROM chip that can be rewritten with special EEPROM update software provided by the manufacturer of the chip. Using EEPROM has become the typical way to update your BIOS. BIOS code is designed to work with certain hardware. As hardware improves, you need to update your BIOS code so that your system is aware of these hardware improvements. Therefore, the manufacturer places BIOS updates on its Web site to download for computer users running its particular BIOS. You just have to download the BIOS update program and then run the BIOS update on your system. The update rewrites the BIOS instructions, making the computer “more aware” of today’s hardware.154 Understanding the Types of Memory Random access memory (RAM) Of the two flavors of memory (ROM and RAM), RAM is probably the more fundamental. As I mention earlier, ROM is permanent memory, or permanent storage of information. As the computer’s primary working memory, though, RAM stores information temporarily. RAM is volatile, meaning that it needs constant electrical current to maintain the information that resides in its chips. If the electrical current is lost, RAM contents are erased. Likewise, when a computer is powered off, all RAM contents are flushed out. The following sections discuss the different types of RAM. On the exam, you can expect a few questions about the different types of memory, so be sure that you are familiar with these different types of RAM. DRAM Dynamic RAM (DRAM) is probably the most popular type of memory today and the one that you are most often going to upgrade. When someone says to you, “I have 1024 megs of dynamic RAM,” he or she is talking about DRAM. Dynamic RAM gets its name from the fact that the information stored in DRAM needs to be constantly refreshed. Refreshing involves reading the bits of data stored in DRAM and then rewriting the same information back. Note: DRAM is single-ported: You can read and write to the memory but not at the same time. Older implementations of RAM measured the memory’s performance based on how long it took the CPU to access that data. This time is measured in nanoseconds (ns; 1 ns equals one-billionth of a second). If you have memory that is 50 ns and your best friend has memory that is 70 ns, your memory is presumably faster. Your CPU receives the information from memory after waiting only 50-billionths of a second, whereas your best friend’s CPU waits 70-billionths of a second. The lower the number of nanoseconds, the better the performance. The speed of older DRAM ranges from 60 ns to 80 ns. Today’s implementations of DRAM measure the speed of memory in megahertz (MHz), typically matching the motherboard speed. For example, my Pentium II system uses 100 MHz memory because it runs on a 100 MHz motherboard. For more information on the types of DRAM, see the section “Identifying the Types of DRAM,” later in this chapter.Book II Chapter 3What to Remember about Memory 155 Understanding the Types of Memory SRAM Static RAM (SRAM) — so-called because the information held in its memory cells doesn’t need to be refreshed — requires less overhead than DRAM to maintain the information stored in memory. With speeds running from 10 ns to 20 ns, SRAM is much faster than DRAM. Because SRAM is faster memory than DRAM, it is also more expensive, which is why people add DRAM to their systems more often than they add SRAM. SRAM is typically used for cache memory, which stores frequently used data and program code after it is read from slower DRAM. Think of cache memory as a bucket that sits beside the CPU and stores frequently used information. After the system has searched through DRAM once for specific information, it can store that information in the bucket for easy access later. The next time the data is requested, it is read from cache instead of from system memory. Because cache memory is much faster than DRAM, the CPU first tries to retrieve the information from cache: specifically, L1 cache first and then L2 cache. If the information is not located in cache, the system then tries to retrieve the information from memory. If the information is not located in system memory, it then is retrieved from disk. Attempting to retrieve the requested information from cache first reduces wait time if the information actually resides there because of how fast cache is compared with DRAM. Cache memory (SRAM) stores frequently used data and program code. Because cache memory is faster than DRAM, retrieving information from cache means that the processor does not have to wait for the slower DRAM, thus enhancing system performance. CMOS RAM The complementary metal-oxide semiconductor (CMOS) is the area where the computer stores its configuration information, such as whether the computer has a floppy drive, the amount of memory installed, the date and time for the system, and the number and size of the hard drives that are installed. Think of CMOS information as an inventory list for the majority of components that are installed on the computer. For more information on CMOS, see Book II, Chapter 4. Where is CMOS information stored? Is CMOS information stored on the BIOS chip, or perhaps another ROM chip? The answer is neither. In fact, if the information were stored on a ROM chip, you wouldn’t be able to go into the CMOS setup program and change the configuration. Instead, CMOS configuration information is stored in a type of RAM called CMOS RAM.156 Identifying the Types of DRAM CMOS RAM is a special, volatile RAM chip that stores the CMOS information. If power is lost, the information is wiped out. This could present a problem with regard to CMOS configuration because if CMOS RAM is wiped out, the computer forgets its inventory information and has to relearn it. To prevent this problem, computers have a small battery on their motherboards that maintains enough of a charge to prevent CMOS RAM from losing its data. CMOS information is stored in CMOS RAM, which is volatile memory that maintains its information by using a battery stored on the system board. Shadow RAM Part of the boot process involves copying some of the BIOS instructions from ROM to RAM and then executing those instructions from RAM rather than from the ROM chip. Why? Because ROM is much slower than RAM, performance speed increases when executing the instructions from RAM instead of ROM. The process in which a copy of the BIOS instructions is shadowed, or copied, to an area of memory called “shadow RAM” is shadowing. VRAM Video RAM (VRAM) is most commonly used on video accelerator cards to store values of pixels onscreen for refresh purposes. VRAM is the favored memory for video because it outperforms the other memory types because it is dual-ported memory: that is, it can be read from and written to at the same time. Comparatively, DRAM is single-ported, which means that the memory can be written to and read from, but not simultaneously — only one direction at a time. VRAM, however, allows you to do both simultaneously. WRAM Window RAM (WRAM), also known as “Window accelerator card RAM,” is a modification of VRAM and is also used for video display purposes. Like VRAM, WRAM is dual-ported memory but runs about 25% faster. In general, WRAM offers better performance than VRAM. Identifying the Types of DRAM DRAM is the most popular type of memory used in systems today. It is also the most popular type of memory that computer users add to their computers when upgrading memory. Therefore, you must understand the different types of DRAM and what types of DRAM outperform others.Book II Chapter 3What to Remember about Memory 157 Identifying the Types of DRAM Standard DRAM Memory is organized into rows and columns, like a spreadsheet. Information is stored in the different cells, or blocks, that are created by the intersection of these rows and columns. With standard DRAM, the CPU requests data from the memory controller by sending the address of the row and the address of the column for every block of data that needs to be read. The memory controller then fetches the information from that memory location. Figure 3-1 shows two memory cells that hold data that the CPU wants to have. Figure 3-1: Looking at how data is accessed in memory. 10 0 234 1 2 4 3 5 To access the information shown in Figure 3-1, the CPU follows these basic steps to request information from standard DRAM: 1. In the first clock cycle, it sends the row address (1). 2. In the second clock cycle, it sends the column address (2). 3. On the third clock cycle, the memory controller reads the information (Address 1-2). 4. In the fourth clock cycle, the row address for the second memory cell is given (1). 5. In the fifth clock cycle, the column address for the second memory cell is given (4). 6. In the sixth clock cycle, the second memory cell is read (Address 1-4). Fast page mode Fast page mode (FPM) improves the performance of standard DRAM by not requiring a row address for each request to memory, assuming that the next block of data is on the same row (which in most cases will be true). The following step list outlines the basic steps to access the same two blocks of data shown in Figure 3-1 via FPM memory:158 Identifying the Types of DRAM 1. In the first clock cycle, the CPU sends the row address (1). 2. In the second clock cycle, it sends the column address (2). 3. On the third clock cycle, the memory controller reads the information (Address 1-2). 4. In the fourth clock cycle, the column address is given (4). 5. In the fifth clock cycle, the second cell address is read (Address 1-4). You can see in this example that it takes less time to read both blocks of data from memory with FPM DRAM. Therefore, FPM memory is a faster DRAM memory type than standard. Extended data output Extended data output (EDO) memory is about 10 to 15% faster than FPM memory and is usually found on 66 MHz motherboards. With EDO memory, the memory controller can read data from a memory block while listening for the next instruction. This capability increases performance because the memory controller does not have to wait for the next instruction after reading a block of memory; while it is reading one block of memory, it is receiving the next instruction. In contrast, with FPM DRAM, reading one memory block and listening for the next instruction are done in multiple steps. Burst extended data output Burst extended data output (BEDO) is a bursting-type technology. The word “burst” refers to the fact that when one memory address is requested and that address is retrieved, the system bursts into the next couple of blocks and reads those as well. The theory behind BEDO is that the system has already gone through the trouble of locating that block, and chances are that the next request will be for the next block, so why not take that informattio while the memory controller is already there? If that extra block is the next requested block from the CPU, the memory controller already has the data and can pass it to the CPU immediately. BEDO is 50% faster than EDO. Because of lack of support from computer manufacturers, however, BEDO has not been used in many systems. It has been surpassed by SDRAM instead. Synchronous DRAM Synchronous DRAM (SDRAM) is memory synchronized to the system board speed. This synchronized speed means that the data stored in memory is refreshed at the system speed, and data is accessed in memory at the system speed as well.Book II Chapter 3What to Remember about Memory 159 Identifying the Types of DRAM SDRAM is one of the most popular types of DRAM found in earlier Pentium systems, such as the Pentium II. When you upgrade memory on your system and you determine that you need SDRAM, you then need to determine what speed of SDRAM. Because you are running at the system speed, you must match the DRAM speed with the motherboard speed. Thus, if you have a 100 MHz motherboard, you need 100 MHz SDRAM. If you have a 133 MHz motherboard, you need 133 MHz SDRAM. As I mention, for a 100 MHz motherboard, purchase 100 MHz memory, which is typically labeled PC100. Be aware, however, that there is some flexibility when purchasing SDRAM. For example, I have a 100 MHz motherbooar on an old Pentium II system. When I upgraded the DRAM on this system, I couldn’t buy PC100 memory because PC133 (which is SDRAM that runs at 133 MHz) was the popular memory at that time. Not a problem! You can use faster memory than your motherboard speed as long as you are willing to accept that you have paid for memory that will not run to its full potential speed. In my example, the 133 MHz memory runs at only 100 MHz because of the speed limitations of the motherboard. Rambus DRAM When SDRAM was popular, a high-speed flavor of DRAM was on the market — rambus DRAM (RDRAM) — which runs at speeds around 800 MHz! RDRAM chips have a 16-bit internal bus width and are packaged together in a 184-pin, gold-plated memory module called a rambus inline memory module (RIMM). To take advantage of this type of memory, you need a motherboard and chipset that support RDRAM. Due to the cost of RDRAM, it lost the popularity contest to SDRAM and eventually DDR memory. DDR Double data rate (DDR) memory gets its name from the fact that it can transfer data twice during each clock cycle, compared with SDRAM that can transfer data only once per clock cycle. DDR memory ships in 184-pin DIMM modules (see the section “DIMMs,” later in this chapter) for desktop computers and 200-pin SODIMMs for laptop systems. DDR memory speed is measured in MHz, like SDRAM is, and is labeled to indicate the speed. DDR memory labeling might look obscure at first because it also indicates the bandwidth by taking the speed and multiplying it by 8 bytes of data (64 bits). Here’s how to read DDR memory labeled as PC1600: Divide the 1600 by 8 bytes to get the speed of the memory. In this case, you are looking at 200 MHz memory. PC2700 runs at 333 MHz, and PC3200 runs at 400 MHz. When you upgrade memory on systems that require DDR memory, you need to know the speed of the DDR memory.160 How Would You Like Your Chips Packaged? DDR2 and DDR3 Improvements to DDR memory have already started with DDR2 memory. DDR2 memory runs at speeds 400 MHz and higher, which is where DDR memory left off. DDR2 memory uses 240-pin memory modules and runs at 1.8 volts (V), as opposed to 2.5V for DDR memory. This results in less power consumption for more memory, which is great for laptop users. Popular modules of DDR2 memory are PC3200 (400 MHz), PC4200 (533 MHz), PC5300 (666 MHz), and PC6400 (800 MHz). The newer form of DDR memory is DDR3, which offers twice the data rate of DDR2 memory. One of the goals of DDR3 memory is to reduce power consumptiion reportedly, DDR3 memory reduces power consumption by about 30%. DDR memory modules are 240-pin DIMMs for desktop PCs and 204-pin SODIMMs for laptop systems. (Read more on DIMMS and SODIMMs in the next section.) Like DDR2, DDR3 memory is advertised by the speed and transfer rate. For example, DDR3-800 (also known as PC3-6400) is 800 MHz memory that has a throughput of 6400 MBps. DDR3-1066 (also known as PC3-8500) memory has a throughput of 8533 MBps. Another example is DDR3-1600, which is 1600 MHz memory with a transfer rate of 12800 MBps. How Would You Like Your Chips Packaged? Whether you are purchasing or installing RAM, understanding the different types of memory packages available is important. The following sections identify different memory packages used in desktop computers and laptop systems. SIMMs Single inline memory modules (SIMMs) used to be one of the most popular types of memory modules, but they have been replaced by DIMMs (see the next section). A SIMM card holds a number of memory chips and has an edge connector containing a number of pins that make contact with the motherboaard This design makes it quite a bit easier to install memory than it was many years ago. In the past, you had to take a dual inline package (DIP) chip out of the system board and reinsert a new chip. Today, you purchase a card of chips (a SIMM) and install the SIMM into one of the SIMM sockets. SIMMs come in two flavors — 30-pin and 72-pin — which describe the number of connectors that make contact with the motherboard. Before buying a SIMM, review the documentation for the computer or look at the system board to determine what size SIMM module you need. Figure 3-2 shows a 30-pin SIMM, a 72-pin SIMM, and a 168-pin dual inline memory module (DIMM).Book II Chapter 3What to Remember about Memory 161 How Would You Like Your Chips Packaged? Figure 3-2: Looking at SIMM and DIMM memory modules. 30-pin SIMM 72-pin SIMM 168-pin DIMM The 30-pin SIMMs have an 8-bit data path, meaning they supply information in 8-bit blocks. When installing memory into a system, you must install enough SIMMs to fill a memory bank. A memory bank is the number of SIMMs it takes to fill the data path of the processor. For example, if you have a system with a 486 processor, the processor is a 32-bit processor. Therefore, the processor wants to deal with information in 32-bit chunks. When using 30-pin SIMMs, you need to install four of them at a time to fill a memory bank because each 30-pin SIMM supplies only 8 bits of data (8 bits × 4 SIMMs = 32-bit chunks). The 72-pin SIMMs supply information in 32-bit chunks. Therefore, if you are installing 72-pin SIMMs on a system using a 32-bit 486 chip, you need just one SIMM to fill a memory bank and the data path. If you are installing 72-pin SIMMs in a Pentium system, you must install SIMMs in pairs because the Pentium data path is 64-bit; to fill a bank on these systems, you need two 32-bit modules (72-pin SIMMs). Remember the data path of the SIMM modules. You should also know how many SIMMs it takes to fill a memory bank on different systems. Remember that a memory bank is the number of memory slots needed to fill the data path of the processor. In this day and age, you most likely will not see SIMMs in a system unless you are supporting older computers. If you see a system that uses SIMMs, it most likely conforms to the 72-pin format.162 How Would You Like Your Chips Packaged? You can easily distinguish what size SIMM a system uses, even if you don’t have the documentation for that system. The 72-pin SIMMs have a notch close to the center of the module. If SIMMs are already installed in the system, take them out and examine them. They usually have a label with a 1 or a 72, representing the pin numbers, at either end of the module. If you see a number 72, you know you have a 72-pin SIMM. DIMMs Dual inline memory modules (DIMMs) are like SIMMs, but they supply information in 64-bit chunks. DIMMs come in different flavors that have a different number of pins on the modules. Older DIMMs use 168 pins for SDRAM and 184 pins for DDR memory; and newer DIMMs use 240 pin modules for DDR2 and DDR3 memory. DIMM modules are a little larger than the 72-pin SIMMs. (Refer to Figure 3-2.) SIMMs come in 30-pin and 72-pin flavors, but DIMMs come in different flavors. The original DIMMs were 168 pins. DDR DIMMs come with 184 pins, and DDR2 and DDR3 DIMMs use 240-pin modules. DIMMs are also the most popular type of memory module that you will find in systems today. Consider the memory bank issue again. Because the DIMM supplies data in 64-bit chunks and the data path of a Pentium processor is 64 bit, you can install DIMMs singly in a Pentium system. On the other hand, you must install SIMMs in pairs in a Pentium system. Figure 3-3 shows what 72-pin SIMM and 168-pin DIMM sockets look like. SODIMM Small outline dual inline memory modules (SODIMMs) are memory modules that are smaller than normal DIMMs and are used in laptops. A SODIMM comes in three different-sized modules: a 32-bit 72-pin module; a 64-bit 144-pin module (SDRAM); and a 64-bit 200-pin module for DDR and DDR2 laptop memory. Figure 3-4 compares a SODIMM and a DIMM. MicroDIMM A micro dual inline memory module (MicroDIMM) is another memory module used in laptop computers. The MicroDIMM is smaller than the SODIMM and comes in a 144-pin module for SDRAM and a 172-pin module for DDR memory.Book II Chapter 3What to Remember about Memory 163 How Would You Like Your Chips Packaged? Figure 3-3: Looking at memory sockets on a motherboaard Four 72-pin SIMM slots Two 168-pin DIMM slots Figure 3-4: Comparing a SODIMM and a DIMM. SODIMM DIMM164 Understanding Error-Checking Memory Understanding Error-Checking Memory Two primary types of error-checking memory have been used in systems over the years. The following sections introduce you to these two types of error-checking memory. Be sure to become familiar with them for the exam. Parity versus nonparity Parity memory is a type of error-checking memory, which is memory that verifies the information stored in memory is what is actually read from memory at a later time. Nonparity memory, comparatively, is memory that does not perform any kind of error checking to ensure that the data written to memory is what is actually read when it is retrieved. Here’s how parity memory works. The two types of parity memory are odd and even. Both parity methods function the same way but differ in the sense of whether they look for an odd number of bits or an even number of bits. This discussion uses odd parity as the example. With parity memory, for every byte (8 bits) of data written to memory, there is an additional ninth bit — the parity bit. When storing information to memory, the number of the enabled data bits (bits set to 1) written to memory are added up. With odd parity, if an even number of data bits are enabled, the parity bit is set to 1 (enabled) so that there is an odd number of enabled bits in total written to memory. If the result of all the enabled data bits is odd, the parity bit is set to 0 (disabled) so that the odd number of enabled bits is retained. After the parity bit has been set, the byte of data and the parity bit are writtte to memory. Even parity works the same way except that it looks for an even number of enabled bits; if the number of enabled bits is odd, the parity bit is enabled. When the CPU requests data from memory, the data byte is retrieved along with the parity bit that was generated when the byte of information was stored in memory. The system looks at the data byte and calculates whether the parity bit stored in memory should be set to 1 or 0. It then compares the answer it has just generated with the value of the parity bit stored in memory. If the two match, the integrity of the information in memory is considdere okay, the parity bit is stripped from the data byte, and the data is delivered to the CPU. If the two differ, you have a parity error, meaning that there is a problem with the integrity of the data stored in memory. Parity memory cannot correct the error; it just reports that an error exists.Book II Chapter 3What to Remember about Memory 165 Single Channel Versus Dual Channel Parity memory has an extra bit (the parity bit) for every 8 bits of data. SIMMs with parity come in 9-bit (30-pin SIMM) or 36-bit (72-pin SIMM) flavors. Also, remember that a parity error indicates something wrong with the integrity of data stored in memory. ECC memory Error-checking and correction (ECC) memory is memory that can detect data integrity problems the way that parity memory can. (See the preceding section.) The difference between the two is that ECC memory can recover from the error and attempt to fix the problem with the data being read, whereas parity memory cannot. Single Channel Versus Dual Channel When installing memory today, you can install memory modules into a dual-channel configuration versus a single-channel configuration. A singlechaanne configuration (used for years) mandates a “single lane” used to send and receive information from memory. With some of today’s systems, though, you can install memory in a dualchaanne configuration, which allows for two lanes to carry information to and from memory at the same time. This configuration increases overall performaanc by allowing for more input/output per operation, or clock cycle. To take advantage of dual-channel memory, you first need to ensure that your motherboard supports dual channel. Dual-channel memory is a functiio of the memory controller. If your motherboard supports dual-channel memory, you will install the memory modules in pairs. For example, when installing 1GB of RAM, you install two 512MB modules. When you install these modules, install them into the same color slots on the motherboard. If the motherboard does not color-code the memory slots, you install the pair of memory modules in the odd-numbered slots or the even-numbered slots — but not an odd and an even. To leverage-dual channel memory, you must install the same memory modules in pairs. You must use the same type (for example, DDR2 or DDR3) of memory for both modules and the same speed. The two modules must be able to keep up with one another when performing parallel IO. You can purchase dual-channel memory kits to ensure that you are using the same type of memory and the same speed. You do not need to use these kits, but you are paying for the fact that someone has already tested the memory in a dual-channel configuration. Some benchmarks report that you 166 Single Sided Versus Double Sided can achieve a 65% increase in memory performance by using a dual-channel configuration. You can use a program called CPU-Z (www.cpuid.com/cpuz.php) to check to see whether you are running your memory in a dual-channel configuration. Single Sided Versus Double Sided Memory modules are either single-sided or double-sided memory modules, but this characteristic does not mean that the memory chips exist on only one side of the memory card or both sides of the memory card (which is what most people think). For single-sided memory, all the memory on the memory module is accessed at once by the system and is treated as a single “bank” of memory. It is important to note that the memory chips on a single-sided memory module may exist on both sides of the memory board. For double-sided memory, the memory module (or memory board) is divided into two discrete chunks of memory (banks).The system can access only one bank at a time. Original double-sided memory modules were creatte by taking two single-sided memory modules and connecting them. Working with Cache Memory Cache memory stores frequently used data and program code after it is read from slower DRAM. Cache memory is made up of SRAM, which is much faster than DRAM. The average speed of DRAM is 60 ns, whereas the averaag speed of SRAM is 20 ns. If at all possible, you want the CPU’s request for information to be serviced by cache memory for a quicker response. To help service these responses, the system has two major levels of cache memory: L1 and L2, which are popular; and also L3 cache, which is making its way on systems today. L1 cache Level 1 (L1) cache is “internal cache” integrated into the CPU. This memory is typically a small amount of SRAM integrated into the processor’s chip, giving the processor instant access to this memory with no wait time. Wait time is how long it takes between when the processor requests information stored in memory and it actually receives that information. Every pre-Pentium processor has L1 cache integrated into the processor chip, but the amount of L1 cache can vary. For example, the 486 chips had 8K of L1 cache, whereas the early Pentium processors had 16K of L1 cache. Newer processors have doubled that amount to 32K of L1 cache.