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Re: [midatlanticretro] Re: makeshift IBM monitor

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  • 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 1 of 23 , Jun 1, 2009
      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 2 of 23 , Jun 2, 2009
        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 3 of 23 , Jun 2, 2009
          > 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 4 of 23 , Jun 2, 2009
            --- 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 5 of 23 , Jun 2, 2009
              -------- 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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