SDS 940

SDS 940
Type	Mainframe computer
Release date	1966
Units sold	60
Operating system	SDS 940 Time-Sharing System, originally the Berkeley Timesharing System
CPU	Transistor based custom 24-bit CPU
Memory	16 and 64 kilowords of 24 bits + parity, additional 4.5 MB swap
Storage	96 MB at 117 kB/s, access time 85 ms
Graphics	Instructions of beam motion, character writing, etc, 20 characters per second. 1000-character terminals with 875-line screen.
Connectivity	Paper tape, line printer, modem

The SDS 940 was Scientific Data Systems' (SDS) first machine designed to directly support time-sharing. The 940 was based on the SDS 930's 24-bit CPU, with additional circuitry to provide protected memory and virtual memory.

It was announced in February 1966 and shipped in April, becoming a major part of Tymshare's expansion during the 1960s. The influential Stanford Research Institute "oN-Line System" (NLS) was demonstrated on the system. This machine was later used to run Community Memory, the first bulletin board system.

After SDS was acquired by Xerox in 1969 and became Xerox Data Systems, the SDS 940 was renamed as the XDS 940.

^ Laws, United States Congress Senate Committee on the Judiciary Subcommittee to Investigate the Administration of the Internal Security Act and Other Internal Security (1975). Terroristic Activity: Hearings Before the Subcommittee to Investigate the Administration of the Internal Security Act and Other Internal Security Laws of the Committee on the Judiciary, United States Senate, Ninety-third Congress, Second Session ... U.S. Government Printing Office. p. 513. (...) XDS-940 computer is a second generation computer (...)
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