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[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System Chipset and Controllers | Chipset Functions and Features | Chipset Memory Support ]

DRAM Packaging and Size Support

Memory for desktop computers comes in two basic types of packages: the SIMM (single in-line memory module) and DIMM (dual in-line memory module). SIMMs come in two sizes: 30 pins and 72 pins. DIMMs are 168 pins. These packages differ not only in physical size but also in the "width" of the memory they can output at once. 30-pin SIMMs produce 8 bits of data at a time, 72-pin SIMMs 32, and DIMMs 64 bits.

The width of memory needed by the motherboard depends on how the chipset accesses memory, and on the data bus width of the processor. In general, 486 class machines require 32-bit wide memory and Pentium and Pentium Pro machines require 64-bit wide memory, but the chipset design has an influence on this. Some Pentium motherboards will handle 32-bit wide memory (slowly) by changing the way memory is accessed.

The design of the chipset is also a limiting factor on how many SIMM or DIMM slots the motherboard can have. Better chipsets support more slots, giving you more flexibility in setting up and upgrading your PC.

Next: Parity and Error Correction Support

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