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Thread: Olivetti M24 and IMD -> No interrupt from FDC

  1. #51
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    The M24 keyboards take a 12V feed, but operate from 5V, as there's a 7805 regulator in the keyboard. Why it was done this way, I have no idea. The signalling is certainly TTL levels.

  2. #52
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    Yes, that's why I wrote about the keyboard. One thing forgotten: All M240 have bus converter, not like M24 "low cost" version.

  3. #53
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    Quote Originally Posted by Chuck(G) View Post
    I wonder if there's an official 6300 BIOS listing around...
    There is! "System Programmer's Guide AT&T Personal Computer 6300" has it starting on page 8-37. Copy here: ftp://ftp.oldskool.org/pub/drivers/A...ter%206300.pdf

    I'd love an answer to the mystery, if you have time. If it's trivial, I could try fixing IMD.

    Quote Originally Posted by Chuck(G) View Post
    The odd thing is that I would have expected to hear about this sort of thing 30+ years ago, not now.
    As a former 6300 owner who used it exclusively from 84-89, all I can say is that 1. it happened a lot, and 2. we got used to being disappointed.
    Offering a bounty for:
    - The software "Overhead Express" (doesn't have to be original, can be a copy)
    - A working Sanyo MBC-775, Olivetti M24, or Logabax 1600
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

  4. #54
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    Shame that I gave away my 6300, but I wasn't using it.

    About the only thing that jumps out at me is that the 6300 uses the specific EOI in its interrupt routine (66h) rather than the nonspecific (20h) that the PC, etc. use.

    I'm not sure how the 8259 is set up to see if that makes a difference.

  5. #55
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    If you could provide me a kind of test software which reads those things from the machine and displays / writes to file these results, I can test for you. I'll be able to test on M21/M24 with BIOS 1.36 and 1.43 and for comparison on M240.

    Not having an M24/6300 is a big error, nicest XT ever, besides the 5150. Today M24/6300 got unbelieveable expensive (on ebay)...

  6. #56
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    If I can't use it, I don't want it around. I'm not a collector--about a year and a half ago, I gave away a 6300 with 80MB hard drive as well as a TRS-80 Model 16 to the only person who would drive up and get them. I advertised here and got no responses. I'd have put more in his car, but there was no room.

    When a system isn't being used and is taking up space, it's a burden. There's nothing that a 6300 could be used for that any other machine couldn't also do.

  7. #57
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    As far as a test program goes, didn't I post a Read ID program here a couple of weeks ago under the subject of aligning floppy drives? Try that as a test for starters.

  8. #58
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    Hello, in this thread? http://www.vcfed.org/forum/showthrea...-Floppy-Drives I Can't find the file...?

  9. #59
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    There were several "how do I align a floppy drive". Let's see if I can find the file...

    Here it is

  10. #60
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    readidm240.jpg
    That is readid on M240 for reference to see how it should behave. It has constant floppy access until I press a key.

    readidm21.jpg
    That is readid on the M21/M24, it shows only that and accesses a while on the floppy, then floppy stopps for a while, starts again, ... but display does not change.

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