single inline memory modul (SIMM)
A Single Inline Memory Module (SIMM) is a memory bar that is equipped with RAM memory components and can be plugged into a special slot on the motherboard.
SIMM modules are single-row or double-row and are mounted vertically or horizontally. The contact connections of the slot can have different distances, namely 1.27 mm (1/20 inch) or 2.54 mm (1/10 inch). SIMM sockets are available in single-row versions with a pitch of 1.27 mm with 64, 72 and 80 terminal contacts, and in double-row versions with 128 (2x64), 144 (2x72) and 160 (2x80) terminal contacts. Single-sided versions with 2.54 mm pitch have 30 connection contacts, double-sided 60 (2x30).
SIMM memory modules serve as working memory for the PC, which is expanded by adding SIMM modules. SIMMs must always be inserted in pairs into the motherboard's memory bank. The access times for SIMM modules are between 60 ns and 70 ns, and memory sizes of 4, 8, 16, 32, 64 and 128 megabytes( MB) can be selected. SIMM modules have been replaced by DIMM modules on motherboards.