The MSM81C55-5 has a 2k-bit static RAM (256 bytes) with parallel I/O ports and a timer. It uses silicon gate CMOS technology and consumes a standby current of 100 micro ampere, maximum, while the chip is not selected. Featureing a maximum access time of 400 ns, the MSM81C55-5 can be used in an MSM80C85AH system without using wait states. The parallel I/O consists of two 8-bit ports and one 6-bit port (both general purpose). The MSM81C55-5 also contains a 14-bit programmable counter/timer which may be used for sequence-wave generation or terminal count-pulsing.
The MSM81C55-5 is a 2 k‑bit static RAM (256 bytes) that includes two 8‑bit parallel I/O ports, a 6‑bit port, and a 14‑bit programmable timer. It is built with silicon‑gate CMOS technology and operates from a single 3 V to 6 V supply.
The document provides full pin configurations for DIP, QFP and QFJ packages, absolute maximum ratings, timing diagrams, and mechanical dimensions for surface‑mount and through‑hole versions.
| Static RAM size | 2 k‑bit (256 bytes) |
|---|---|
| Standby current | 100 µA (max) |
| Maximum access time | 400 ns |
| Operating temperature range | -40 °C – +85 °C |
| I/O ports | Two 8‑bit ports (PA, PB) and one 6‑bit port (PC) |
| Timer width | 14‑bit programmable counter/timer |
The device operates from a single supply voltage of 3 V to 6 V.
It draws up to 100 µA of standby current when not selected.
It provides two 8‑bit general‑purpose I/O ports (PA and PB) and one 6‑bit port (PC).
The device is rated for operation from –40 °C up to +85 °C.