I was moving things around in the workshop today and decided to do a quick eval on two of the machines in my collection. You may recognize the IMSAI 8080 from the movie "Wargames". (note it's not THE IMSAI 8080, it's just AN IMSAI 8080). The Altair 8800 is a super basic model of that machine - it only has a four slot backplane (S-100 bus) and no floppy or tape boards. I'm not sure what it was originally used for. The original owner may have gone to a different platform instead of upgrading the Altair.