The SDS Sigma 7 was one of the first computers sold commercially with the hardware to support memory virtualization and user/supervisor modes. It got some earl

The SDS Sigma 7 was one of the first computers sold commercially with the hardware to support memory virtualization and user/supervisor modes. It got some early time-sharing use. SDS later got bought by Xerox, and carried the business forward into the 1980s, where they eventually got squeezed out, IIRC. They were a big player for a while, but mostly for pragmatic factory installations, online calculator services, library catalog lookup, stuff like that, not the associated programmer/hacker culture, so the machines are now mostly forgotten. The LCM apparently had one? https://commons.wikimedia.org/wiki/File:LCM_-_Xerox_Sigma_9_(right)_and_related_equipment_-_01.jpg https://commons.wikimedia.org/wiki/File:LCM_-_Xerox_Sigma_9_...