UPGRADING REPAIRING PCs

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modules can be divided by 9, but the number of bits in non-parity
modules can be divided only by 8.
Table 2.16 SIMM and DIMM Capacities
30-Pin SIMM Capacities
Capacity Parity SIMM Non-Parity SIMM
256KB 256KB×9 256KB×8
1MB 1MB×9 1MB×8
4MB 4MB×9 4MB×8
16MB 16MB×9 16MB×8
72-Pin SIMM Capacities
Capacity Parity SIMM Non-Parity SIMM
1MB 256KB×36 256KB×32
2MB 512KB×36 512KB×32
4MB 1MB×36 1MB×32
8MB 2MB×36 2MB×32
16MB 4MB×36 4MB×32
32MB 8MB×36 8MB×32
64MB 16MB×36 16MB×32
128MB 32MB×36 32MB×32
168-Pin DIMM Capacities
Chapter 2—System Components and Configuration
Capacity Parity DIMM Non-Parity DIMM
8MB 1MB×72 1MB×64
16MB 2MB×72 2MB×64
32MB 4MB×72 4MB×64
64MB 8MB×72 8MB×64
128MB 16MB×72 16MB×64
256MB 32MB×72 32MB×64
Expanding Memory on a System
Memory must be added to a system in banks. Simply put, a bank of
memory is the amount of RAM in bits equal to the data bus width
of the computer’s CPU (see Table 2.17). Thus, a Pentium’s data bus
is 64 bits, and a memory module(s) used with a Pentium must have
a total width of 64 bits for non-parity memory and 72 bits for
parity-checked or ECC memory.