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    I guess you already have found this:...

    I guess you already have found this:
    http://www.bitsavers.org/pdf/osborne/2F00040-00_Service2ndEdition_1983.pdf
    Didn't you?
    Starting on page 236, there's the manual for the Motorola MD1000-190...
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    Yes, sorry, I should have mentioned that I also...

    Yes, sorry, I should have mentioned that I also have the cardboard "dummy" insert. That releases the top head lifting mechanism, like when a normal floppy is inserted. Sorry, it's been a while since...
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    The only "fix" that I've found is to never ever...

    The only "fix" that I've found is to never ever leave a 1571 door open, unless when extracting a disk (of course).
    It may take some time to find the correct amount of twist to correct it. Give too...
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    The top head of a 1571 is lifted by only one side...

    The top head of a 1571 is lifted by only one side support. This causes after many years a little twist in the head orientation and it's not sitting flat against the disk surface anymore, plus isn't...
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    If that's the ML monitor that was commonly used...

    If that's the ML monitor that was commonly used in the 1980's then I am almost sure it never supported labels, it's a direct assembler only. Back in the old days (and I do the same still nowadays...
  6. Yes if you have a Basic 2 PET (the ### at...

    Yes if you have a Basic 2 PET (the ### at startup, would be Basic 3 in my scheme) it's normal.
    Static RAM 2001 had for sure the possibility to run up to Basic 4, I've been told that 6540 ROMs were...
  7. Ok sorry, that's my "own" numbering system. Basic...

    Ok sorry, that's my "own" numbering system. Basic versions on PETs are the following (that I've seen in real life)
    1) Basic 1 "unpatched", found on 2001 static versions, very rare but they do exist...
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    The "dead short" might be intentional as probably...

    The "dead short" might be intentional as probably one end of both +5V and +12V secondaries goes to a common negative rail (0V), you're measuring basicly the very low resistance of both secondaries in...
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    I have the habit of never buying NOS chips from...

    I have the habit of never buying NOS chips from China (or other old parts), since I've got fakes or bad parts in the past.
    Today I've ordered a MB7052 TTL PROM from a german seller, for a ridicoulus...
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    I have recently fixed a TTL PROM chip (out of a...

    I have recently fixed a TTL PROM chip (out of a Disk II interface card) that kept on losing pins (iron oxide does that, as soon as the tin plating starts having holes), so if the only problem of the...
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    Thanks all, I've found a person in Italy that can...

    Thanks all, I've found a person in Italy that can do the job. I'll post a followup when it's done, just to let other know.
    Best
    Frank
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    Interesting list, thanks! I might have found an...

    Interesting list, thanks!
    I might have found an Italian guy who has a Data I/O 29B and could do the job.
    I'm looking for a 29B myself since years, but it is very difficult to find in EU (and...
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    Need MB7052 programming service (EU)

    Hi all,
    as part of an arcade PCB repair (vintage cpu board, so kind on topic!), I need a new MB7052 256x4 TTL PROM. I can't program TTL proms with my current programmers (and I've been trying to...
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    Thanks for sharing Hugo! That's highly...

    Thanks for sharing Hugo! That's highly interesting!
    Frank
  15. Well, yes, you should also look at pin 11 which...

    Well, yes, you should also look at pin 11 which is driven by the PET and compare with 9 which is the receive pin of the same line. However NDAC is handled by both UC6 and UC5, so you might try...
  16. The banks are 2, only the $f000-$ffff segment has...

    The banks are 2, only the $f000-$ffff segment has 4 possible mappings. I'm quite sure both basic 3 and 4 are complete and working, since I've just duplicated the image I'm using myself on my 2001 and...
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    Hello! I have designed adapters for 6540 ROMs...

    Hello!
    I have designed adapters for 6540 ROMs and 6550 RAMs myself. I can give you the gerbers to order the PCBs yourself or provide a built and tested one, but that will be expensive mostly because...
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    I completely agree with Dave. It looks like a 510...

    I completely agree with Dave. It looks like a 510 ohms one, but I'd not take chances and just measure the twin one.
    Frank
  19. Or input multiplexers for video ram has shorted...

    Or input multiplexers for video ram has shorted inputs.
    However, since it's not doing that always as the signal appear to get "normal", I don't know what to guess really. Is the frequency of all...
  20. It would be useful to see those signals at the...

    It would be useful to see those signals at the UC3.7 and UB3.3

    Frank
  21. oh, and obviously goes into the motherboard...

    oh, and obviously goes into the motherboard databus also for $8000-$8FFF (because of the video ram).

    Frank
  22. Hi Dave, the version of the RAM/ROM board that...

    Hi Dave,
    the version of the RAM/ROM board that he have, only access the original PET bus from $E800 to $E8FF. ROMs can be selected in 4K ranges (for example, $F000 to $FFFF can be accessed on the...
  23. Hi Dave, your mod looks ok to me. However I've...

    Hi Dave,
    your mod looks ok to me. However I've found more effective to make a little daughterboard adapter to replace these kind of ROMs, so I don't need to modify the hardware.
    Unfortunately, my...
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    hmm 6.63V isn't really a good sign unless your...

    hmm 6.63V isn't really a good sign unless your multimeter is out of calibration by a large margin. Are these voltage taken with no cables attached to the 1541? All those 0V mean faults.
    It's...
  25. The good thing about 6502 ML is the conditional...

    The good thing about 6502 ML is the conditional jumps don't need any relocation. If all JMP/JSR are labeled, you just change .org directive, add the start vector in the RESET vector locations and...
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