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Thread: 5150 U33 BIOS with ‘82 version anomaly?

  1. #1
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    Default 5150 U33 BIOS with ‘82 version anomaly?

    So I took a dump of the U33 chip on my non-working 5150 that I found on the side of the road. This chip is an NEC D2364AC016. The hex dump showed “1501476 COPR. IBM 1982” in the first section, so I downloaded a copy of the 10/27/82 revision of BIOS (from minus zero) to compare it. It almost matches exactly, except a bit near the beginning, and a bit near the end.

    I can provide a copy of the file if anyone is interested. I don’t know if it’s a corrupt chip, something that went wrong while reading it, or a previously unknown version of BIOS. Who knows, maybe this is why the motherboard “appears” dead.

  2. #2
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    Quote Originally Posted by FiveGHz View Post
    Who knows, maybe this is why the motherboard “appears” dead.
    That's what I am putting my bet on.

  3. #3

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    Quote Originally Posted by FiveGHz View Post
    5150 that I found on the side of the road.
    Man, what roads are you driving on? I'd love to start finding IBMs on the side of the road.
    Current favorites: IBM 5160 (EGA+Hercules, 4 floppies, ST-225, XT-IDE), Compaq Portable ii (replaced PSU and keyboard, EMS card), ASR 33 Teletype (needs work), Apple ][e
    Wishlist: Toshiba Libretto docking station, IBM 5161 (expansion chassis), IBM Professional Graphics Controller (PGC), IBM 3270 PC keyboard card, Tandy disk-video interface (for Model 100-series), DG Nova IO controller, and the meaning of life.

  4. #4
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    Quote Originally Posted by modem7 View Post
    That's what I am putting my bet on.
    On closer inspection I was mistaken, the year reads “1981” and the rest of the hex matches the 1982 BIOS exactly except the last bit in the file is 77 vs. 78. It does not resemble either 1981 BIOS images at all.

  5. #5
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    Quote Originally Posted by Nevets01 View Post
    Man, what roads are you driving on? I'd love to start finding IBMs on the side of the road.
    It was shear luck, probably a very rare occurrence.

  6. #6
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    Quote Originally Posted by FiveGHz View Post
    On closer inspection I was mistaken, the year reads “1981” and the rest of the hex matches the 1982 BIOS exactly except the last bit in the file is 77 vs. 78. It does not resemble either 1981 BIOS images at all.
    Which suggests that the content is not corrupt/damaged (i.e. not the cause of your non-working 5150).

    Quote Originally Posted by FiveGHz View Post
    This chip is an NEC D2364AC016.
    Like the 'NEC D2364' on one my early 5160 motherboards, pictured in the top photo at [here].
    Note the seven-digit IBM part number ("5000027") that is printed on the chip.
    Does yours have a seven-digit IBM part number printed on it ?

  7. #7
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    Quote Originally Posted by modem7 View Post
    Does yours have a seven-digit IBM part number printed on it ?
    It’s hard to tell. Here is a picture but the text is a bit worn off.

  8. #8
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    I looked at it again under macro lens with different light. Seems to be 1501476, which would match the 10/27/82 BIOS

  9. #9
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    Popping the IR filter from a cheap webcam results in a good tool for reading faded IC printing.

  10. #10

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    Quote Originally Posted by Chuck(G) View Post
    Popping the IR filter from a cheap webcam results in a good tool for reading faded IC printing.
    hmm I wonder if that works with NVGs too, I'll have to try it sometime

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