Systems Concepts, Inc. (now the SC Group), was a company co-founded by Stewart Nelson and Mike Levitt focused on making hardware products related to the DEC PDP-10 series of computers. One of its major products was the SA-10, an interface which allowed PDP-10s to be connected to disk and tape drives designed for use with the channel interfaces of IBM mainframes.
Later, Systems Concepts attempted to produce a compatible replacement for the DEC PDP-10 computers. "Mars" was the code name for a family of PDP-10-compatible computers built by Systems Concepts, including the initial SC-30M, the smaller SC-25, and the slower SC-20. These machines were marvels of engineering design; although not much slower than the unique Foonly F-1, they were physically smaller and consumed less power than the much slower DEC KS10 or Foonly F-2, F-3, or F-4 machines. They were also completely compatible with the DEC KL10, and ran all KL10 binaries (including the operating system) with no modifications at a