Memory Cards
Most PC technicians do not think of memory modules as expansion cards, but in the
strictest interpretation of an expansion card, the memory modules used to add memory
to a PC are just that. As discussed in detail in Chapter 7, memory modules are like little
expansion cards that are mounted on the motherboard in slot sockets. The two general
categories of memory modules used on PCs are SIMM (single inline memory modules)
andDIMM(dualinlinememorymodules).Figure11-13showsamemorymoduleinstalled
on a motherboard.Memory Expansion Card (MEC)
Higher-end microcomputers, such as those in use as network servers or engineering or
graphics workstations, often need more memory even after they have already filled the
memory module slots. In cases like these, the solution is to install a special expansion
card, called a Memory Expansion Card (MEC). A MEC can add up to 16GB of additional
RAM (usually SDRAM) to a computer. One slight drawback is that the MEC sits on the
system bus and is therefore slower than the memory mounted in the SIMM or DIMM
slots on the motherboard. However, when weighed against the benefit of additional
memory, the advantages far outweigh the disadvantages. Figure 11-14 shows a drawing
ofaMECmodulemanufacturedbyDellComputerforitsworkstationlineofcomputers.Chapter 11: Expansion Cards^233
Figure 11-13. Memory modules are installed in slot sockets on the motherboard