MOTHERBOARD

Identifying Components

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Photo from PC Guide

Motherboard Components and Function

Follow along referencing
Motherboard Integrated Components
from PC Guide.

Function: The motherboard is a printed circuit board (PCB) that contains and controls the components that are responsible for processing data.

Description: The motherboard contains the CPU, memory, and basic controllers for the system. Motherboards are often sold with a CPU. The motherboard has a Real-time clock (RTC), ROM BIOS, CMOS RAM, RAM sockets, bus slots for attaching devices to a bus, CPU socket(s) or slot(s), cache RAM slot or sockets, jumpers, keyboard controller, interrupts, internal connectors, and external connectors.

The bus architecture and type of components on it determine a computers performance. The motherboard with its ribbon cables, power supply, CPU, and RAM is designated as a "bare bones" system.

Clock: The motherboard contains a systems clock to synchronize the operation of the bus and other components. Jumpers on the motherboard allow a user to set different clock rates to work with the CPU. Other jumpers control other components on the motherboard.

286 and 386 motherboards had an extra socket on board for a math coprocessor. The coprocessor is responsible for non-integer calculation. It is also known as an FPU or Floating Point Unit. 486DX's and all generation of Pentiums have a math coprocessor already built into the CPU chip.

The motherboard determines: (info taken from Motherboard HomeWorld)

  • CPU type and speed
  • Chipset Type (the specialized chips that control the memory, cache, external buses, and some peripherals)
  • Secondary cache type
  • Types of expansion slots: ISA, EISA, MCA, VESA local bus, PCI and AGP slots

    See Bus page at this site for detailed information.


    ISA slot (pronounced as separate letters or as eye-sa) (Industry Standard Architecture) - 1980's - 8 bit + 16 bit path
    EISA (Extended Industry Standard Architecture) - 32 bit path
    MCA (MicroChannel Bus) - 32 bit path - 64 contacts
    IBM's 32-bit bus for the PS/2 machines.
    VESA slot (Video Electronics Standards Association) - (also called VLB & VL-bus) - 32 bit path - About 4 incges longer than ISA

    PCI slot (Peripheral Component Interconnect) - 64 bit path - 33MHz - clocked 132 MB throughput
    AGP slot (Accelerated Graphics Port) - 64 bit path - 64 contacts- clocked [(2Xmode)33 Mhz = 66MHz} = 528 MB thropughput - for true 3D

  • number of slots
  • type of memory (EDO, SDRAM, parity, ECC, etc.)
  • number of memory sockets and maximum memory
  • type of case and P/S
  • ROM (this will most certainly already be installed)
  • Plug and Play compatibility
  • type of keyboard connector

All these parts you will become familiar with as move through this course.

Identification of Components

See how well you are at identifying motherboard components by looking at the pictures below.

Identification of Component Functions

What is the function of each of the below components?





Identifying Form Factors

The most recent motherboards are classified into the following three form factors. See Description of Form Factors #1 and The Description of Form Factors #2.

1. Baby AT Form Factor

AT and BAT Form Factor from PC Guide.
Older At = 12" wide, Newer = 10" and 11" long.
BAT = 8.5" wide and 13" long.
5 pin, large keyboard connector
Motherboard Single Row, 2 connectors.
I/O requires cables.
Specific placement of components.

2. ATX Form Factor


ATX and Mini ATX Form Factor from PC Guide.
ATX =12" wide X 9.6" long; mini ATX = 11.2" X 8.2";
MicroATX = 9.6" square
I/O Connectors on motherboard.
Integrated P/S2 Ports.
Processor socket/slot and memory sockets are moved from the front of the board to the back right side, near the power supply.
Single 20-pin motherboard connector (double row single connector) instead of the confusing pair of near-identical 6-pin connectors on the baby AT.
I/O built onto board single or dual stack.
3.3V Power Support.
6 pin, small keyboard connector
Specific placement of components.

4. Slimline LPX Riser Form Factor


PCTechGuide

LPX and Mini LPX Form Factor from PC Guide.
Riser card that is used to hold expansion slots.
System bus on a riser card that plugs into the motherboard.
Only two or three expansion slots.
Video display adapter cards built into the motherboard.

3. Slimline NLX Riser Form Factor


NLX Riser Form Factor
PCTechGuide

NLX Form Factor from PC Guide.
8.8" wide X 13" long
Riser card for expansion slots.
Adds DIMM memory modules.
Support for SEC and AGP.
Cables, such as the floppy drive interface cable, attach to the riser.

Location: The motherboard is attached to the bottom of the case. In a tower or mini-tower, the motherboard is attached vertically to one side of the case.

Upgrading: "Remember, you must have a motherboard that will support your processor. Don't expect to buy a 486 motherboard and then put a Pentium processor on it. It won't work since the motherboard was not designed to handle any Pentium processors. If you look at the motherboard, see if there is a ZIF (Zero Insertion Force) socket. The socket is were you put your processor in. In the old days, you have to really press the processor into the socket with a lot of strength. It is pretty risky cause you might damage the motherboard if you press the processor with too much strength. With the ZIF socket, you just lift a handle, place the processor in, and pull the handle down to secure it. This way, no force was used to put the processor in (you just drop it into the socket), so you reduce the risk of damaging parts.

Just like processors, sockets come with different types - from Socket 1 to Socket 8. Each of them will only support certain processors. I.e.: Socket 5 will only support Pentium. Socket 7 will support 486 and Pentium. (Note: Socket 1 to 7 are for 386 to Pentium, Socket 8 only supports Pentium Pros.) Make sure the motherboard supports a wide range of processors. Some will only handle Pentium 66 to 100 MHz. Others will support Pentium 75 to 200 MHz. If it supports a wide range, you can upgrade your computer easily since it supports so much processors. If you plan to upgrade to a processor that was not supported by your motherboard, (let say you want to upgrade to a Pentium 166 MHz but your motherboard will only support up to Pentium 100 MHz) then you would have to change your motherboard too.

The MMX Pentium chips are a type of Pentium chip that have new commands in addition to the current Pentium chips. They contain new instructions that are specially written for multimedia functions. To use the MMX Pentium chips, the motherboard has to support it."

Quote above taken from http://www.geocities.com/SiliconValley/Hills/2339/mboard.htm.

PLUG N' PLAY (PnP)

Plug-and-play is a system built into newer systems so that you can install devices built for it more easily. After installation of new hardware, all of the settings, like IRQ's and drivers, are taken care of on start-up. A PnP system scans the entire system for new hardware every time the system is booted. Windows 95 will detect the new hardware, adjust the settings, and install the drivers. It also determines what every device needs, and makes sure it gets it.

The Macintosh had PnP before the PC did. Not all systems can handle PnP. You must have

  • a PnP operating system, such as Windows 95. Previous versions of Windows can't do it.
  • Your hardware must be rated for PnP.
  • You need 32-bit drivers for the device...not to worry though...they come with it.
  • And lastly, your BIOS must be compliant with PnP.

Internal Components, Chipsets, continued...

The PC Technology Guide Online

PCGuide Online

Motherboard Installation

Motherboard Installation from PC Guide.

Motherboard Installation Installation of all Components

Motherboard Configuration Procedure from PC Guide.

Motherboard and Case Connection from PC Guide.

ADDITIONAL NOTES TO LARGE PHOTOS ABOVE

TAG RAM: "In addition to the 256KB or 512KB of CPU Cache RAM on these modules, some modules also have what is know as TAG RAM on them.

This is a small additional RAM Module which is used by the CPU to keep track of from which segment of DRAM an instruction has been loaded into the Cache RAM. Normally, CPU Cache ram modules such as these have "single-tagged" TAG RAM, which allows use with up to 64MB of DRAM. If you use MORE THAN 64MB OF DRAM, YOU MUST SPECIFY A DIFFERENT TAG RAM SIZE!!!. With up to 128MB of DRAM, you MUST specify "Double TAG RAM".

If you do not have enough TAG RAM for the size of DRAM you use, the CPU goes ahead and thinks it has it anyway, and you WILL get bit-errors when the CPU reads the instructions from the DRAM into CPU Cache! This will make the system stop and "hang"!! You could also accidentially corrupt data in this way, as the CPU will be "tricked" into believing it is getting other instructions than the ones it was actually supposed to get!!!!!" For Pentium Pro and Pentium II microprocessors, the tag RAM is integrated in the chipset. Quote taken from http://www.inside-us.com/support/faqs/gcacheram.htm

COASt Socket: A type of socket for Secondary Cache ram. Called Cache On A Stick: It is another popular design specification for cache modules. It resembles a SIMM but is a little shorter and plugs into a COAST socket, which is normally located close to the processor and resembles a PCI expansion slot. Remember for Pentium II's Cache is built into the chipset.

SCSI (Small Computer System Interface): An American National Standards Institute (ANSI) interface between the computer and peripheral controllers. SCSI excels at handling large hard disks and permits up to eight devices to be connected along a single bus provided by a SCSI connection. Also features in Narrow, Wide and UltraWide flavours.

USB (Universal Serial Bus): Intel's new standard for attaching peripherals to PCs. Designed for low to medium data throughput, it should remove the need to install many devices internally once it gains widespread acceptance.

Universal Serial Bus allows virtually unlimited PC expansion "outside the box." With USB, PC users no longer need to worry about selecting the right serial port, installing expansion cards, or the technical headaches of dip switches, jumpers, software drivers, IRQ settings, DMA channels and I/O addresses. Future versions of the Windows operat ing system will come already equipped with the feature (called "drivers") that allows your PC to recognize USB peripherals.

USB is a Plug-and-Play interface that allows up to 127 peripherals to plug sequentially into a single external port, using just a single interrupt and port address

ASIC's: Application-Specific Integration Circuits or Chipsets.

AGP: AGP also requires software support, including both the OS and graphics drivers. Windows 95 and NT4 can be modified to support AGP, but Windows 98 has built-in support. NT5 will have built-in support for AGP. Windows 95 users can get the Windows 95 OEM Service Release 2.1 or a patch program called USBSUPP.EXE. Your current Win95 PCI device driver will support AGP, but you will need to get DirectX5, which is the only version of DirectX to support DIME. You must make sure your video drivers include VGARTD.VXD as well. This is a virtual device driver that turns on the DIME feature.

Further Information:

Identify your motherboard manufacturer by your Award Bios Number at Wim's Bios Page or your AMI Bios Number at Wim's Bios Page.

See Motherboard and Bios manuals for download in PDF file format. Includes Intel motherboard diagrams for identification.