Used in NCOM03/04, IMCOM03/04 and other Bailey Controls modules.
The Dallas DS1220 (including its popular variants like the DS1220AB and DS1220AD) is a 16-kilobit non-volatile static RAM (NVRAM) chip that can retain memory data for more than 10 years without external power. It is organized as 2,048 words by 8 bits (2 kilobytes of storage) and features a built-in lithium battery and power-monitoring circuitry encapsulated inside a thick black plastic DIP package.