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12864Re: [midatlanticretro] makeshift IBM monitor

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  • Bill Degnan
    Jun 1, 2009
    • 0 Attachment
      Remember when you work with the manual not to confuse the directions and
      settings for the 16K-64K board and the 64K-640K board. They're both in the
      manual. I have more info on my web site, vintagecomputer.net/ibm. Also
      search the blog for various notes and pictures about this model. I have
      restored three of these models in the past 12 months.

      Usually what kills them is the monitor card, usually if you replace the
      card the system comes back to life. The other likely thing to go wrong is
      RAM. I can teach you some tricks to locating the bad RAM and replacing.

      Bill

      -------- Original Message --------
      > From: "Joe Giliberti" <Starbase89@...>
      > Sent: Monday, June 01, 2009 3:03 PM
      > To: midatlanticretro@yahoogroups.com
      > Subject: Re: [midatlanticretro] makeshift IBM monitor
      >
      > I downloaded a PDF copy of the technical manual last night. I'm guessing
      the
      > onboard RAM are the 27 or so small chips near the front visible corner
      of
      > the board? I'll get all relevant information you asked for, including
      switch
      > positions, and get back to you.
      > Joe
      >
      > On Mon, Jun 1, 2009 at 2:55 PM, Bill Degnan <billdeg@...>
      wrote:
      >
      > >
      > >
      > > Joe,
      > > Do you have a copy of the technical reference manual? If not I can
      copy
      > > and scan the important pages. In the mean time can you take a picture
      of
      > > the motherboard switches, and RAM? If not easy to do, can you just tell
      me
      > > whether there are open RAM slots and what the switches are set to? I
      am
      > > guessing it's a 64K + 512K with the QuadRAM card = 640K. With this you
      > > could do almost anything. Lastly, what are the markings on the ROM
      chips
      > > in U33? That will tell me if it has an upgraded ROM or the original. I
      am
      > > going to guess that it's been upgraded.
      > >
      > > I don't off hand know the voltages. The 8087 coprocessor is next to
      the
      > > processor near the power connector.
      > >
      > > Thanks
      > > Bill
      > >
      > >
      > > -------- Original Message --------
      > > > From: "Joe Giliberti" <Starbase89@...
      <Starbase89%40gmail.com>>
      > > > Sent: Monday, June 01, 2009 2:45 PM
      > > > To:
      midatlanticretro@yahoogroups.com<midatlanticretro%40yahoogroups.com>
      > > > Subject: Re: [midatlanticretro] makeshift IBM monitor
      > > >
      > > > All I've done thus far is apply power to the power supply (which is
      > > > original). What are the voltages supposed to be going into the
      mainboard?
      > >
      > > I
      > > > want to check with a multimeter before hooking it to the
      motherboard.
      > > It
      > > > appears to have the co-processor installed. I do plan on doing a
      > > > methodological, slow restore on it.
      > > >
      > > > Aside from resocketing chips and removing dust, what is the
      procedure
      > > for
      > > > checking the motherboard?
      > > >
      > > > Joe
      > > >
      > > >
      > > > On Mon, Jun 1, 2009 at 9:38 AM, Bill Degnan
      <billdeg@...<billdeg%40degnanco.com>>
      > >
      > > wrote:
      > > >
      > > > >
      > > > >
      > > > > May I add that this is quite a lucky find, you may never get such
      a
      > > rare
      > > > > system in the trash ever again, you take this as an opportunity to
      > > perform
      > > > > a serious restoration/save. Learn about what you have and make the
      most
      > >
      > > of
      > > > > the experience. Don't try to hook this up to the Internet, try to
      > > return
      > > > > the computer to original condition. Don't power this up until
      you're
      > > > > confident you have tested the power, removed all cards and
      unhooked
      > > power
      > > > > to the motherboard, etc.
      > > > > Bill
      > > > >
      > > > >
      > > > > -------- Original Message --------
      > > > > > From: "Mr Ian Primus" <ian_primus@...
      <ian_primus%40yahoo.com>
      > > <ian_primus%40yahoo.com>>
      > > > > > Sent: Monday, June 01, 2009 8:08 AM
      > > > > > To:
      > > midatlanticretro@yahoogroups.com <midatlanticretro%40yahoogroups.com>
      > > <midatlanticretro%40yahoogroups.com>
      > > > > > Subject: Re: [midatlanticretro] makeshift IBM monitor
      > > > > >
      > > > > > --- On Sun, 5/31/09, Joe Giliberti
      > > <Starbase89@...
      <Starbase89%40gmail.com><Starbase89%40gmail.com>>
      > > > > wrote:
      > > > > >
      > > > > > >there is a bit of rust on the cover, but not significant. I'm
      using
      > > a
      > > > > >random AT keyboard, as I do not have a model M
      > > > > >
      > > > > > An AT keyboard will not work on this machine. You need an XT
      > > keyboard.
      > > > > The plugs are the same, but the protocol is different. Some early
      AT
      > > > > keyboards also have a switch (sometimes hidden behind a little
      panel in
      > >
      > > th
      > > > > bottom) to switch between AT and XT modes.
      > > > > >
      > > > > > The original CGA card has RCA plugs on it, and if I remember
      > > correctly,
      > > > > it should be composite video. But, I do believe that the composite
      > > video
      > > > > output does not support all video modes that the CGA card can do.
      Your
      > > best
      > > > >
      > > > > bet is to find a real monitor...
      > > > > >
      > > > > > You can't connect the CGA card to a VGA monitor, but you CAN use
      > > (with
      > > > > limited color palette), an analog RGB monitor, such as the ones
      used on
      > >
      > > the
      > > > >
      > > > > Commodore Amiga. CGA is a digital RGB, and uses an intensity line.
      The
      > > > > analog monitors will display the digital signal, but can't use the
      > > > > intensity line - so all the "light" colors come out as the same
      color
      > > as
      > > > > their "bright" counterparts. It's usable though.
      > > > > >
      > > > > > -Ian
      > > > > >
      > > > > >
      > > > > > ------------------------------------
      > > > > >
      > > > > > Yahoo! Groups Links
      > > > > >
      > > > > >
      > > > > >
      > > > >
      > > > >
      > > > >
      > >
      > >
      > >
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