Microsoft Basic, Computer Archeology

Visitors of my Retro website may have seen a copy of Microsoft Basic for the KIM-1, the KB9 version online. Not only the original tape in binary format, also the small user guide that was delivered with it.

This Microsoft Basic for the 6502 is one early member of the family of Basic interpreters for the 6502 produced by Microsoft in their early days. Also the Apple II and Commodore machines and many more had this interpreter and an extension to function as an operating system as Basic. Paul Allen, Monte Davidoff, ill Gates, Richard Weiland and Marc McDonald are persons in the Microsoft company that contributed to this interpreter.

Michael Steil, who blogs at, refers to my online files while explaining not only the history and timeline of these Basic interpreter versions, but also publishes the commented source.

By using conditional assembly one can recreate seven OEM versions, not only KIM Basic KB9.

  • Commodore BASIC 1
  • AppleSoft I
  • Commodore BASIC 2 (PET)
  • Intellivision Keyboard Component BASIC
  • MicroTAN BASIC

It feels good to see the KB9 files on my site to have been of use for Michael, since he refers to the files on several places.
Quite amusing is the search for the famous Easter Egg in all these Basics (type WAIT 6502,1 and see ‘MICROSOFT!’ printed).

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