(NOTE: Not all motherboards include all components in this illustration, and not all will look the same as those illustrated here. For more detailed descriptions of most motherboard com- ponents, see the accompanying article.)
A
motherboard is at the core of every com- puter system. In desktop models it usu- ally lines the floor of the system. In tower and mini-tower models, it lies along one of the sides. A motherboard’s components and fea- tures define a PC’s potential and upgrade path. Virtually every essential computer part, data bus, or electrical subsystem attaches to the motherboard in some way. If the mother- board fails, the computer will not function.You can identify a computer mother- board by the components that attach to it and the layout of its parts. The most important motherboard component is the microprocessor or CPU. Other significant components include the number of memo- ry slots onboard, the maximum amount of memory the board supports, available PCI (Peripheral Component Interconnect) slots, the system bus or maze of wires connect- ing the CPU to the PC’s numerous compo- nents, whether the board has integrated audio or modem circuitry, and the range of speeds supported by the processor.
As the motherboard works, data and tim- ing signals transfer from one connected
component to another by way of intercon- nected leads etched into the board. These leads are known as the system bus. The power supply (which also connects to the motherboard) distributes power to system components via the bus. The processor also communicates with motherboard compo- nents by sending and receiving instructions and data over the bus.
A motherboard is designed to take advan- tage of particular technology. For example, certain processors function correctly only when installed on particular motherboards and chipsets. You won’t be able to take advantage of new technology (a speedier processor or different type of graphics, for example) if the board installed in your com- puter lacks the appropriate circuitry.
How Motherboards Work
ISA (Industry Standard Architecture) Bus Slot
Real Time Clock/
CMOS (complementary metal-oxide semiconductor) Memory
Case Pin Connectors
PCI Bus Slots
Floppy Header
PS/2 Mouse Header
Keyboard Connector P7
Slot USB
(Universal Serial Bus) Header
Keyboard Controller
BIOS (Basic Input/Output System) Chip The BIOS holds the instructions that start up your computer, and it lets your comput- er’s hardware and operating system
"talk" to applica- tions and periph- eral devices.
AGP (Accelerated Graphics Port)
SIMM Sockets Reserved for RAM, which stores actively running applications and their data.
Tag RAM Socket
System Chipset The collection of logic circuits responsible for transferring data and instructions to and from all other motherboard circuits, adapter card connectors, and disk drives.
CPU Socket Also known as the central processing unit, microprocessor or "brains" of the computer, it is a major component that determines computer performance.
On-board Secondary Cache Chips Reserved for a partic- ular kind of fast memo- ry called SRAM (static RAM). The cache stores operations or data recently accessed by the CPU.
Capacitors Primary
IDE Header Parallel Port Header
Secondary IDE (Integrated Drive Electronics) Header Serial
Ports
Jumpers The illustration to the right shows how a
typical RAM chip slides in to the appropriate motherboard socket. Most cards and boards insert in a similar way.
Compiled by Carol S. Holzberg, Ph.D.
Graphics & Design by Jason Codr
