A Lost IBM PC/at Model? Analyzing a Newfound Old Bios

(int10h.org)

56 points | by TMWNN 5 hours ago ago

9 comments

  • sema4hacker 7 minutes ago

    My OCD tendencies would have made me label the one chip ..ODD.. instead of .ODD... just for a little more symmetry.

  • eek2121 2 hours ago

    Back when I was a teenager, I would have absolutely gone down a rabbit hole like the author did. From "Upgrading and Repairing PCs" to reading all the technical manuals, usenet, etc. I definitely nerded out over this stuff! Glad to see folks still take an interest.

    These days, I've an acquired brain injury. Between that an old age, it was a bit hard to read, but also, just a little bit familiar, so I enjoyed it.

    Now I am expecting "256 color VGA programming in C" to resurface at some point! :D

    Old hardware was always so much fun...

    • mrandish 2 hours ago

      256 colors? VGA?

      Bah! You kids with your newfangled graphics modes. 320 x 200 CGA and 16 colors is more than enough. See the linked "8088 MPH" video for proof: https://trixter.oldskool.org/2015/04/07/8088-mph-we-break-al...

      • m463 an hour ago

        > 320 x 200 CGA

        with the opposite of smooth scrolling - video off during text scrolling. BLINK!

        kind of like the crazy blinking ancestor of vsync off

  • drfuchs 3 hours ago

    Any chance it was for the "IBM Personal Computer AT/370" that nobody remembers (perhaps because nobody used)?

    • viler 2 hours ago

      That was one option I thought of at first (mentioned in the first section), but the info I found indicated that the /370 models used the same firmware as the "plain" 5170s - if there were any BIOS extensions, they were probably somewhere on the add-on cards. The AT/370 also had 512K of on board RAM, while this BIOS seems to indicate 640K.

    • m463 an hour ago

      I remember that. I think it ran VM/SP or whatever it must have been called.

      I recall the 370 part was on a card.

  • mrlonglong 3 hours ago

    Excellent write-up.

    • viler 3 hours ago

      Appreciated, thanks!