related article:
https://technicshistory.com/2025/02/22/from-acs-to-altair-th...
and HN discussion
The January 1975 issue of Popular Electronics featured Micro Instrumentation and Telemetry Systems's (MITS) Altair 8800 microcomputer,[13] which inspired Allen to suggest that they could program a BASIC interpreter for the device. Gates called MITS and claimed that he had a working interpreter, and MITS requested a demonstration. Allen worked on a simulator for the Altair while Gates developed the interpreter, and it worked flawlessly when they demonstrated it to MITS in March 1975 in Albuquerque, New Mexico. MITS agreed to distribute it, marketing it as Altair BASIC. Gates and Allen established Microsoft on April 4, 1975, with Gates as CEO,[14] and Allen suggested the name "Micro-Soft", short for micro-computer software.