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Thread: IBM PC 5150 and IBM PC XT 5160 FAQ

  1. #11

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    Did any of them refuse to pay the royalty? (I'm assuming you're referring to clone motherboards and not ISA cards...)

    g.
    Proud owner of 80-0007
    http://www.f15sim.com - The only one of its kind.

  2. #12
    Join Date
    Feb 2012
    Location
    Hampshire, England
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    160

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    Some of them tried. The problem for the clone manufacturers was that IBM owned some of the fundamental patents for building a PC, be it ISA or Micro Channel. In fact at the time of announcement, the Micro Channel patents were still pending and so Micro Channel machines were licensed for EXACTLY the same set of patents as ISA boxes. BTW, IBM only charged licences for complete PCs, motherboards and adapter cards were license free.

    At the time it really irked me that IBM failed to explain all of this properly. I well remember that I found out later, that on the 2nd August 1987, while I was briefing one set of journalists about Micro Channel and how it was still open architecture (In fact we documented Micro Channel much better than we ever did with the PC/PC AT.) one of our moronic executives who would not have recognised a PC if it bit him was threatening all and sundry with law suits!

  3. #13
    Join Date
    Jul 2010
    Location
    Silicon Forest, Oregon, USA
    Posts
    684

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    Quote Originally Posted by dongfeng View Post
    64-256kB 5150:
    I was wondering about the purpose of the 74LS32 installed in U101 (which is a spare location). Some boards have it, some don't.
    Apparently the explanation is following: AMD DMAC (Am9517 aka 8237 by its Intel's designation) had a bug, probably something related to CPU writing to the DMA while a DMA operation was in progress. This bug was fixed by adding that 74LS32, some wires, and probably a few cut traces on the PCB. Interestingly enough the board on the picture appears to have an Intel made 8237, and still has the U101 patch work.

    Here is the IBM ECA that mentions this issue: http://www-05.ibm.com/services/ecalib/doc/5150-005.txt. Note that they call DMAC a "processor" .

    Other threads mentioning this bug / fix:
    http://www.vintage-computer.com/vcfo...revision-board
    http://www.vintage-computer.com/vcfo...IC-Differences

    Newsgroups references:
    http://groups.google.com/group/net.m...3ab53bc25ad3c6
    https://groups.google.com/group/comp...c8573a0adefa15

    5150-related ECAs (not sure if they are mentioned elsewhere):
    http://www-05.ibm.com/services/ecalib/doc/5150-001.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-002.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-003.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-004.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-005.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-006.txt
    Last edited by sergey; April 20th, 2013 at 04:38 PM.

  4. #14

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    Quote Originally Posted by Beerhunter View Post
    Not the case. This myth that non-IBM Personal Computers were free of IBM royalties until Micro Channel came along is just that - a myth.
    I actually read some of the old InfoWorld etc articles on this matter, and one article said that it tended to be 5% for MCA systems once the patents were granted vs ~3% for PC AT compatibles.
    Last edited by yuhong; April 20th, 2013 at 05:46 PM.

  5. #15

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    Quote Originally Posted by sergey View Post
    I was wondering about the purpose of the 74LS32 installed in U101 (which is a spare location). Some boards have it, some don't.
    Apparently the explanation is following: AMD DMAC (9517 aka 8287 by its Intel's designation) had a bug, probably something related to CPU writing to the DMA while a DMA operation was in progress. This bug was fixed by adding that 74LS32, some wires, and probably a few cut traces on the PCB.
    Very interesting - thanks for posting this.

  6. #16
    Join Date
    Jul 2013
    Location
    Toronto, Ontario, Canada
    Posts
    24

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    I got one of these letters with a 5150 I got from kijiji. Though I share it here in case someone wants a copy.

    Dear New Owner.jpg

  7. #17

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    I have an IBM 5160 that has a BIOS ROM U18 with IBM part number 500026. The ROM is a ceramic package with a gold lid.

    The motherboard is also slighly different than the two shown here:
    http://www.minuszerodegrees.net/5160..._revisions.htm

    Mine has an Intel 8088.

    It also has the number 4073 stamped to the right of the silkscreen "64 - 256KB SYSTEM BOARD"


    I read that nobody has seen one of these motherboards in the wild and have not seen this BIOS PROM.

    Is this system one of the first beta XT's?

  8. #18
    Join Date
    Jan 2005
    Location
    Central New Jersey
    Posts
    1,006

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    apologies if this question has come up. Were all 5150 motherboards brown? Were all 5160 motherboards green?

  9. #19

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    No, they can be either brown or green.

  10. #20

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    Just wanted to mention that you don't absolutely need an expansion chassis to use a hard drive with a 5150. The one I have had a Miniscribe 21MB 3.5" MFM drive working fine with the stock 63.5w power supply, and it's been in the machine since 1987. As long as the power draw isn't too much for the PSU it works fine, even for booting. Newer or smaller drives are more likely to work.

    This isn't exactly a secret, but there doesn't seem to be much mention of using HDDs with these so I figured I'd chime in.

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