The CYM1851 is a high-performance 32-megabit static RAM module organized as 1,024K words by 32 bits. This module is constructed from eight 1,024K x 4 SRAMs in SOJ packages mounted on an epoxy laminate substrate. Four chip selects are used to independently enable the four bytes. Reading or writing can be executed on individual bytes or any combination of multiple bytes through proper use of selects.

The CYM1851 is designed for use with standard 72-pin SIMM sockets. The pinout is downward compatible with the 64-pin JEDEC ZIP/SIMM module family (CYM1821, CYM1831, CYM1836, and CYM1841). Thus, a single motherboard design can be used to accommodate memory depth ranging from 16K words (CYM1821) to 1,024K words (CYM1851). The CYM1851 is offered in vertical and angled SIMM configurations and both are available with either tin-lead or 10 micro-inches of gold flash on the edge contacts.

Presence detect pins (PD_0–PD₃) are used to identify module memory density in applications where modules with alternate word depths can be interchanged.