Forethought Systems produced a motherboard, the KIMSI, for the KIM-1 in 1977 that enables to add 8 S-100 boards to a KIM-1. The S-100 standard, developed for the IMSAI and such 8080/Z80 systems, was a huge success that made affordable standardized systems available, mostly with CP/M as operating system. I acquired a KIMSI in August 2026. Photos and a high quality scan of manual and sales brochure at: