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Re: MARCH IBM PC 5150 rev A Restoration Project Notes

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  • Mike Hatch
    ... will ... IBM PC ... worthy ... need to ... full 64K. I should have a few of those if you want them, let me know. ... there is ... having ... color card.
    Message 1 of 3 , May 23, 2008
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      --- In midatlanticretro@yahoogroups.com, "B. Degnan" <billdeg@...> wrote:
      >
      > Hi all.
      >
      > I have been able to get MARCH's IBM PC 5150 rev A up and running. I
      will
      > post detailed notes on my web site. This is the 16K-64K original
      IBM PC
      > model with original black power supply. Very rare rev "A" model and
      worthy
      > of a museum.
      >
      > In summary
      > -there is bad RAM, but I was able to get a 32K contiguous to function,
      > enough to boot DOS 1.1, but not enough for DOS 2.x or higher. I
      need to
      > find and replace the bad 4116 chip(s) so that the system is using a
      full 64K.

      I should have a few of those if you want them, let me know.


      >
      > -BASIC ROM C 1.0 - (cassette basic 1.0). Note that with 32K RAM,
      there is
      > still 28K available for BASIC. This is due in part to the CGA card
      having
      > it's own memory. I have a good article on the IBM PC in the CISC367
      > directory of my web site if you're interested in more details.
      >
      > -the original mono display card was bad, replaced with a CGA monitor
      > card. Looking for a replacement monochrome. changed settings for
      color card.
      >
      > -the one diskette works - switch settings OK
      >
      > -the dip switches indicated the presence of a 8077 co-processor, but
      none
      > was present. Changed switch to "no co-processor"

      Possibly the co-processor as well but i need to look.


      >
      > Pictures (not renamed yet, but re-sized)
      > http://vintagecomputer.net/ibm/5150/5150_A/
      >
      > I am working on some sort of display for the MARCH exhibit of this
      computer.
      >
      > More news soon. I took notes of the entire restoration "logic"
      >
      > NEXT: replace the RAM, find an IBM monochrome card. more cleaning.
      >
      > Bill
      >

      Mike.
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