Q. Illustrate Single In-line Memory Modules?

From early days of semiconductor memory till the early 1990s memory was manufactured, brought and installed as a single chip. Chip density went from 1K bits to 1M bits and beyond though every chip was a separate unit. Early PCs generally had empty sockets into that extra memory chips could be plugged if and when purchaser required them. At present a different arrangement is frequently used known as SIMM or DIMM.

A group of chips typically 8 to 16 is mounted on a small printed circuit board and sold as a unit. This unit is known as a SIMM or DIMM depending on whether it has a row of connectors on one side or both sides of board.

A typical SIMM configuration may have 8 chips with 32 megabits (4MB) each on SIMM. The whole module then holds 32MB. Many computers have room for 4 modules giving a total capacity of 128MB when employing 32MB SIMMs. The first SIMMs had 30 connectors and delivered 8 bits at an instance. The other connectors were addressing and control. A later SIMM had 72 connectors and delivered 32 bits at an instance. For a machine such as Pentium that expected 64-bits at once 72-connectors SIMMs were paired each one delivering half the bits required.