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Recent content by CommodoreZ

  1. CommodoreZ

    The Kim-100

    Finally caught up with my video backlog, this is good stuff. Thank you for preserving the history of this machine. I was expecting a TVT 6-5/8 or something, rather than an S-100 board, that's cool. A few years ago I asked a few Apple I fans if anyone had kitted out a modern replica with a...
  2. CommodoreZ

    ASCII Keyboard Examples Worth Studying

    74151's and 74138's with a little extra logic to compensate for being separate chips should do the trick.
  3. CommodoreZ

    ASCII Keyboard Examples Worth Studying

    This right here is the kind of thing I'm going for, thank you. I was also supplied with this schematic elsewhere from Polymorphic Systems for the Poly-88 and 8813. No specialty IC's, no dedicated keyboard encoders, not even ROMs -- just pure jellybean logic. I think this might be my baseline...
  4. CommodoreZ

    Which version is it ? ALTAIR 680 or 680b ?

    The link to the previous iteration of this forum doesn't appear to have been archived, so those breadcrumbs are long gone. It's also worth noting that the OP of this thread passed away in 2018.
  5. CommodoreZ

    ASCII Keyboard Examples Worth Studying

    When it came to homebrew computer projects of the 70s and sometimes 80s, the ASCII keyboard is talked about alot, but now kinda relegated to the unobtanium due to keybhoarders and keycap/switch harvesters. So obviously people have come up with new designs to fill the void, which is great. I've...
  6. CommodoreZ

    Is there something special about this?

    Try this link: https://www.ebay.com/itm/396825731326
  7. CommodoreZ

    A vintage computer shipping story in one photo

    How bad is it, beyond the structural/cosmetic damage we can see?
  8. CommodoreZ

    Data General Nova 1200

    So, on the 8K core plane I've been using, I ran the 1200 Logic Test for like 80 minutes non-stop, and it ran without issue for the duration of the test. Then I switched over to the Memory Checkerboard III test, which also ran without issue for over an hour, no faults detected or reported. I...
  9. CommodoreZ

    Data General Nova 1200

    I fixed it? I honestly don't know what happened. I replaced U42. And the tests kept failing. So I had my hand-entered diagnostic routines tested with a second set of eyes. Turns out I had some bits wrong... human error. :oops: I still don't know what initially caused the fault that sent...
  10. CommodoreZ

    I got a Gateway...tell me what to put on it!

    Windows 95 OSR2 sounds like a great choice. As for software, 95 Plus!, Photoshop 4, MS Office 97, Command & Conquer, Red Alert, the Microsoft Best of Entertainment Pack, LEGO Island, Atomic Bomberman, Lode Runner Online: Mad Monk's Revenge, Rollercoaster Tycoon, Warcraft I and II, MS Flight...
  11. CommodoreZ

    Data General Nova 1200

    Okay, we may have found the point of failure, and it's upstream of the part being explored per post #101. This N8271 shift register is used to store a bunch of states as we progress through processing. The signal we care about is how IO*E is generated from IO(F+D). Presumably, that data is...
  12. CommodoreZ

    6502 Front Panels

    Right, so look at the examples above: most of them don't bother to do that. The OSI-300 doesn't even care, it wants you to start from scratch each time with a reset CPU, and it accomplishes its goal. In order to single step an NMOS 6502, you keep the clock running, and instead control single...
  13. CommodoreZ

    6502 Front Panels

    I think that one is a modern machine. Awesome work, but again this modern machine made in the past few years. The thing that killed the front panel was the birth of the Appliance Computer, caused by a combination of circumstances of which came to a head in 1977. I've explored this aspect in...
  14. CommodoreZ

    Data General Nova 1200

    From novasareforever.org: 096-000150-01__Nova_1200_Logic_Test_095-000036-01__1970-1974.pdf which is the manual for 095-000036-01__Nova_1200_Logic_Test__1970-1974.ab
  15. CommodoreZ

    Data General Nova 1200

    It wasn't U11. As far as I can tell, the "P" pulse refers to a special pulse used for interacting with I/O devices. When a No I/O Transfer instruction is sent, which device it applies to depends on the last 6 bits of the instruction. Device code 0 refers to the CPU, and is sort of a dummy...
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