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Re: [midatlanticretro] Re: makeshift IBM monitor

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  • B Degnan
    U33 MK36C35N-4 1501476 ZA (copyright) IBM CORP 1981, 1983 D Malaysia Tells you it s a 2nd REV16K-64K (upgraded) ROM set. The first rev did not have a routine
    Message 1 of 23 , Jun 1, 2009
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      U33
      MK36C35N-4
      1501476
      ZA
      (copyright) IBM CORP
      1981, 1983
      D Malaysia

      Tells you it's a 2nd REV16K-64K (upgraded) ROM set.  The first rev did not have a routine for using hard drives, and some other things so most people upgraded the ROMS so they could use newer parts and memory.



      Here's as much info as I can pull off the mainboard

      Machine Serial:
      0177038
      this year I worked on the following other 16-64K boards, so yours is right in there among them, definitely an original, probably from late 1981 early 1983.:

      0159618
      0239462
      0192592 (MARCH's with original ROMS)

      On the planar:

      SW1
      on on on on off on on off

      SW2
      on off on on off off off off


      you have a full complement of RAM (64K) on the motherboard. 

      I assume you have SW1 reversed.  Up means "on" if facing from the front looking down. 
      If you have a co-processor, two drives, CGA monitor then SW1 should be: [off on -- -- on off off on] (where pertains to RAM).

      If SW1's 5 is up and 6 down  - that means CGA display.  Monochrome 5 and 6 are down.  Never mix and match without first changing the switches before powering on.  Otherwise you will fry the board and short the system.

      Math co-processor 2 = up/on.

      In a nutshell it looks like you have a standard configuration, no changes needed assuming you use a CGA monitor.  Don't try to use monochrome with these settings.  Someone did that to MARCH's 5150, and we had to replace the display card as a result. 

      Hope this helps.

      Bill

    • Joe Giliberti
      Thanks for the info, Bill Some more questions Does it matter whether I take video from the CGA port or the composite? So I could, if I wished, install an MFM
      Message 2 of 23 , Jun 1, 2009
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        Thanks for the info, Bill
        Some more questions

        Does it matter whether I take video from the CGA port or the composite?
        So I could, if I wished, install an MFM hard drive/controller, or perhaps a hardcard. Correct?
        Also, due to the different ROM, will it support a full 640k, or the 544k from the first gen?

        Joe

        On Mon, Jun 1, 2009 at 10:45 PM, B Degnan <billdeg@...> wrote:


        U33
        MK36C35N-4
        1501476
        ZA
        (copyright) IBM CORP
        1981, 1983
        D Malaysia

        Tells you it's a 2nd REV16K-64K (upgraded) ROM set.  The first rev did not have a routine for using hard drives, and some other things so most people upgraded the ROMS so they could use newer parts and memory.




        Here's as much info as I can pull off the mainboard

        Machine Serial:
        0177038
        this year I worked on the following other 16-64K boards, so yours is right in there among them, definitely an original, probably from late 1981 early 1983.:

        0159618
        0239462
        0192592 (MARCH's with original ROMS)


        On the planar:

        SW1
        on on on on off on on off

        SW2
        on off on on off off off off


        you have a full complement of RAM (64K) on the motherboard. 

        I assume you have SW1 reversed.  Up means "on" if facing from the front looking down. 
        If you have a co-processor, two drives, CGA monitor then SW1 should be: [off on -- -- on off off on] (where pertains to RAM).

        If SW1's 5 is up and 6 down  - that means CGA display.  Monochrome 5 and 6 are down.  Never mix and match without first changing the switches before powering on.  Otherwise you will fry the board and short the system.

        Math co-processor 2 = up/on.

        In a nutshell it looks like you have a standard configuration, no changes needed assuming you use a CGA monitor.  Don't try to use monochrome with these settings.  Someone did that to MARCH's 5150, and we had to replace the display card as a result. 

        Hope this helps.

        Bill


      • B Degnan
        ... only use a real cga monitor in the CGA port. do not use the composite. ... yes but this system did not come with a hard drive and would not be in the
        Message 3 of 23 , Jun 2, 2009
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          Joe Giliberti wrote:
          Thanks for the info, Bill
          Some more questions

          Does it matter whether I take video from the CGA port or the composite?
          only use a real cga monitor in the CGA port.  do not use the composite.

          So I could, if I wished, install an MFM hard drive/controller, or perhaps a hardcard. Correct?
          yes but this system did not come with a hard drive and would not be in the spirit of what it was originally.

          Also, due to the different ROM, will it support a full 640k, or the 544k from the first gen?

          full 640.  Should be at 640K now.
          Joe


          P.S. - Evan - the disk you gave me for the IBM at MARCH has some bare spots, the drive needs to be cleaned or replaced.    Do we have any replacement Tandon 100-2a drives at MARCH?

          Bill
        • Evan Koblentz
          ... I don t know.
          Message 4 of 23 , Jun 2, 2009
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            > Evan - the disk you gave me for the IBM at MARCH has some bare spots,
            > the drive needs to be cleaned or replaced. Do we have any
            > replacement Tandon 100-2a drives at MARCH?
            I don't know.
          • Mr Ian Primus
            ... The drive probably just needs a good cleaning. I ve never seen a Tandon in an IBM fail so badly as to scrape up disks. The heads are probably just really
            Message 5 of 23 , Jun 2, 2009
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              --- On Tue, 6/2/09, Evan Koblentz <evan@...> wrote:

              > > Evan - the disk you gave me for
              > the IBM at MARCH has some bare spots,
              > > the drive needs to be cleaned or replaced. 
              >   Do we have any
              > > replacement Tandon 100-2a drives at MARCH?
              > I don't know.

              The drive probably just needs a good cleaning. I've never seen a Tandon in an IBM fail so badly as to scrape up disks. The heads are probably just really dirty. Also, the disk itself could have been compromised - some brands are more apt to start shedding oxide with age.

              -Ian
            • Bill Degnan
              ... in an IBM fail so badly as to scrape up disks. The heads are probably just really dirty. Also, the disk itself could have been compromised - some brands
              Message 6 of 23 , Jun 2, 2009
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                -------- Original Message --------
                > From: "Mr Ian Primus" <ian_primus@...>
                > Sent: Tuesday, June 02, 2009 8:56 PM
                > To: midatlanticretro@yahoogroups.com
                > Subject: Re: [midatlanticretro] Re: makeshift IBM monitor
                >
                > --- On Tue, 6/2/09, Evan Koblentz <evan@...> wrote:
                >
                > > > Evan - the disk you gave me for
                > > the IBM at MARCH has some bare spots,
                > > > the drive needs to be cleaned or replaced.
                > > Do we have any
                > > > replacement Tandon 100-2a drives at MARCH?
                > > I don't know.
                >
                > The drive probably just needs a good cleaning. I've never seen a Tandon
                in an IBM fail so badly as to scrape up disks. The heads are probably just
                really dirty. Also, the disk itself could have been compromised - some
                brands are more apt to start shedding oxide with age.
                >

                True on all counts. I was just curious about whether we had another drive
                if next time I come up and I can't fix the problem, I can bring a spare
                drive if I have one. Hopefully you're right and a good cleaning will
                suffice, or a new disk. The disk in question is a copy of DOS 2.11 with a
                few scratched tracks, but not completely bare. I never had issues with
                these drives when I was working with the system myself, but I was mostly
                focused on the hardware and did not do much disk exercising other than
                format a disk in both drives.

                bd
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