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  1. Chuck(G)

    Sperry Univac D 60 60 ?

    Well, there are two USARTS (8251) on that board, so I think it's quite likely to be able to run on its own--at least enough for the EPROM to execute some code.
  2. Chuck(G)

    Sperry Univac D 60 60 ?

    That's a very good theory. But the cards you show do show a NEC D780, which is NEC's licensed clone of the Z80 (the PAM board). It's got 64KB of DRAM and 2 USARTs, so it's pretty complete. Dumping the PROM might give some additional information.
  3. Chuck(G)

    SCSI Control question

    Yup. E.g. Adaptec 2985 or 3940. Multiple controllers on a card.
  4. Chuck(G)

    Unknown Unibus-like WEITEK CPU board

    Massbus might make some sense.
  5. Chuck(G)

    Bendix G-15 Restoration

    I look at drum computers as a specific case of delay-line computers. For example, the PB250 used magnetostrictive delay lines for memory, with the same 1+1 instruction format. An optimizing assembler helps to put instructions at optimal locations. I don't know if there were any systems that...
  6. Chuck(G)

    Notes for IBM 5110 keyboard replacement (pin out measurements)

    Nice work, but my problem is with BT keyboards in general--they tend to be cheap and terrible. Ideally, you'd want to interface a higher-quality keyboard. I never could feel comfortable typing on a notebook keyboard. That being said, I'm embarrassed to admit that I have several IBM iPoint...
  7. Chuck(G)

    5150 Cannot format floppies

    "Discrete". I have no idea--do the multi-I/O cards have their own BIOS? In any case, if the 765 failed, you'll see the reason in RAM at 40:41h-40:48h. So just trap the return from Int 13H and display the status bytes if an error is returned. Easy.
  8. Chuck(G)

    5150 Cannot format floppies

    That's what it looks like--since the 765 is doing reads in any case, just changing the DMA setup, it certainly makes me suspicious.
  9. Chuck(G)

    5150 Cannot format floppies

    You're not following me. If read and write work fine, then verify, which is the same as a read, but with the 8237 set to non-transfer mode, the only thing that's different is the 8237 timing. I'm saying that the 5150 when doing DMA transfers inserts a wait state if actual memory data is...
  10. Chuck(G)

    Sperry Univac D 60 60 ?

    I'm sure that you've already run across this one But I can't find anything in the TPU line that resembles what you have.
  11. Chuck(G)

    Bendix G-15 Restoration

    For a comparison of this sort of system, consider the Univac Solid State 80 machines. The timing track off the drum runs the whole shebang.
  12. Chuck(G)

    Sperry Univac D 60 60 ?

    Hmmm, made in England with a French keyboard....IC dates around 1981-82. Nice system, BTW--top-shelf quality of construction. My guess is an early office automation system, given the keyboard key legends. Perhaps a predecessor to SperryLink?
  13. Chuck(G)

    Bendix G-15 Restoration

    Has anyone attempted a drum simulator replacement for these?
  14. Chuck(G)

    5150 Cannot format floppies

    Okay, but you have your answer.
  15. Chuck(G)

    Microchannel cards implemented in discrete logic

    I don't doubt it--somewhere here I have a PCI card where the interface is a CPLD (XC9500). You can pack a lot of functionality into relatively simple programmable logic.
  16. Chuck(G)

    Thoughts on minicomputer to microcomputer transition (PDP to Macintosh)

    You are aware, of course, that several systems use decimal floating point in their BASIC for just that reason? Don't assume that floating-point implies binary math. Decimal math was an important part of many mainframe instruction sets. S/360 had it; the lowly 1620 CADET in you benchmark...
  17. Chuck(G)

    5150 Cannot format floppies

    ...which is very strange, because while the 765 is issuing a read, the 8237 is performing a VERIFY, which doesn't involve memory access at all: Since the FDC is still performing a garden-variety read operation, with the data dumped down a black hole by the 8237, you'd think that the timing is...
  18. Chuck(G)

    5150 Cannot format floppies

    Fer the love of &^*&^*!!: In the old days of 5150 and 5160, we'd just take an XCO and feed it into the EFI input on the 8284 and tie the F/C* pin to the 8255--just the way the taiwanese would do it. Of course, in turbo mode, the clock ran a bit fast, but you could use a small TSR to capture...
  19. Chuck(G)

    5150 Cannot format floppies

    This is a 5150 running at 7+ MHz? Didn't know that IBM made them like that. There are some turbo XT clone BIOSes that slow the system clock back down to 4.77MHz when Int 13H access is happening. I suppose that could be done with yours.
  20. Chuck(G)

    5150 Cannot format floppies

    Ah well, it's probably a bus-related issue. Yer running it too fast, mate!
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