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Thread: IBM 5150 motherboard revisions

  1. #1
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    Default IBM 5150 motherboard revisions

    Does anyone know how many motherboard revisions exist for the IBM 5150? I have several boards, many of which have slight variations such as different jumper wires and U101 differences, but I'm curious about major revisions.

    There's the 64k version. There's the 256k version. There's another 256k version in which the memory chips are spaced out differently. Here's a pic ... I haven't seen very many of the later 256k revision... I'm guessing they didn't manufacture many of these? Anyone else seen this one?

    DSC02351_01.jpg

  2. #2

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    There are two main revisions, revision A - 16-64k and revision B - 64-256k.
    Also there are three bios versions.
    Check site http://minuszerodegrees.net/
    IBM PC 5150(A): IBM PC 5150(B): IBM PC 5160 (64-256k): IBM PC 5160 (256-640k): IBM PC 5170 (099): IBM PC 5170 (319/339): IBM PC 5140: IBM PC 5162: IBM PC 5155: IBM PC Expansion Unit 5161:
    WANTED!: IBM 5175 monitor, IBM 5145 monitor, IBM PC/XT/AT rear screws, Intel INBOARD 386AT card, IBM 5140 keyboard, very early IBM PC (S/N: under 5000)
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  3. #3
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    Yes Romanon thanks, I am well aware of that. I'm specifically looking at what appears to be IBM's second revision of the 256k board which has a different layout of the RAM chips. The chip dates on the board are mostly 8617, so my guess is that this revision of the board is possibly from the last production run. Does anyone know more about this version of the board? (See my pic above). This version of the board is not common and I have not seen many of these.

  4. #4

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    1) 16-64KB Rev.A type with BIOS Part No. 5700051 (1981)
    2) 16-64KB Rev.A type with BIOS Part No. 5700571 (1982)
    3) 64-256KB Rev.B Type with BIOS Part No. 1501476 (1983)

  5. #5
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    Ok, listen ...

    Yes, I'm aware that there are 3 BIOS revisions, however, there are more revisions of the board than just that. What I'm talking about here, as is clearly visible in the picture I posted above, is a later revision of the 256k board in which the IBM engineers changed the spacing around the RAM and ROM chips. Still with me so far? Good. We are not talking about BIOS revisions. I'm talking about BOARD REVISIONS. Look at the picture. See the RAM layout? See it? Now look at an earlier 5150 board. Still with me? Good... you'll notice they are DIFFERENT. Got it??

    So I must be the only one in the universe with this version of the 5150 256k board then. Good for me, I guess it is extra rare and nobody knows anything about it other than me. SMH

  6. #6
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    I would have expected Modem7 to weigh in on this. He is usually the big expert on this sort of thing. BTW, Don't be too offended by fs5500, he doesn't really do English to well.

    I don't know much about later revisions, but I find it interesting. Are there any other identifying markings on it? Could you perhaps post some more detailed pictures?

  7. #7
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    Maybe it helps if the question is better understood as how many "variations" are there? (rather than "revisions")

    Gladly snapped some better pics of this board to show more. The pic of the green board is for comparison.

    DSC02363.jpgDSC02364.jpgDSC02365.jpgDSC02366.jpgDSC02370.jpgDSC02371_01.jpgDSC02374.jpg

  8. #8
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    Quote Originally Posted by SomeGuy View Post
    I would have expected Modem7 to weigh in on this.
    I did not respond because the answer is 'no' for both of the questions asked.

    I am not into noticing and documenting differences that do not affect functionality/behavior/specifications, but I appreciate that others are, for various reasons. I have done it ([example]), but it has usually been for something where there are few differences.

    The subject of a desire to document all observed motherboard revisions/differences/variations has been raised on these forums. For all we know, there could be hundreds of motherboard revisions/differences/variations, the number depending on one's definition of revision/difference/variations.

  9. #9
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    Maybe not hundreds, but certainly a lot for sure. I've seen several examples of differences even on the Model A 5150, so who knows with what consistency these revisions are and date to when (my earliest Model A has a non-socketed 8088 with the interrupt bug, among other things).

    Also, aren't "jumper wires" considered rework wires? I've seen it on other vendors, but it seems especially prevalent on IBM stuff. For me, if it works, I could care less about the revision.
    IBM Computers: 5150 (16-64K, 64-256K), 5160, 5161, 5162, 5170 (regular and Tempest), Option 370 16 bit, PC Convertible
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  10. #10
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    Quote Originally Posted by pkhoury View Post
    Also, aren't "jumper wires" considered rework wires?
    Not according to my definition of 'jumper wire'. My definition includes the wire in the IC socket shown at the top-left of the photo at [here]. The wire is 'jumpering' pins in the IC socket. It is not there as part of rework; it is there as part of drive configuration.

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