Datasheet

Identifying Motherboards 17
FIGURE 1.5 Components on a motherboard
CPU
USB ports
IDE connectors
AGP slot
Battery
ISA slot
BIOS chip
COM and
LPT ports
Keyboard and
mouse ports
Power supply
connector
Floppy
connector
PCI slots
RAM
Memory Slots
Memory, or RAM, slots contain the memory chips. There are many and varied types of
memory for PCs today. We’ll further discuss memory later in this chapter. PCs use memory
chips arranged on a small circuit board. These circuit boards are called single inline mem-
ory modules (SIMMs) or dual inline memory modules (DIMMs). DIMMs utilize memory
chips on both sides of the circuit board, whereas SIMMs utilize memory chips on a single
side. There is also a high-speed type of RAM called Rambus dynamic RAM (RDRAM),
which comes on circuit boards called RIMMs (Rambus inline memory module).
Along with chip placement, memory modules also differ in the number of conductors, or
pins, that the particular module uses. The number of pins used directly affects the overall size
of the memory slot. Slot sizes include 30-pin, 72-pin, 168-pin, and 184-pin. Laptop memory
comes in smaller form factors known as small outline DIMMs (SoDIMMs). Figure 1.6 shows
the form factors for the most popular memory chips. Notice that they basically look the
same, but the memory module sizes are different.
Memory slots are easy to identify on a motherboard. They’re usually white and placed
very close together. The number of memory slots varies from motherboard to motherboard,
but the appearance of the different slots is similar. Metal pins in the bottom make contact
with the soldered tabs on each memory module. Small metal or plastic tabs on each side of
the slot keep the memory module securely in its slot.
Central Processing Unit (CPU) and Processor Slots
The CPU slot permits the attachment of the CPU to the motherboard, allowing the CPU
to use the other components of the system. There are many different types of processors,
which means many types of CPU connectors.
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