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7701Re: [midatlanticretro] Restoration news from InfoAge.

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  • B. Degnan
    Apr 2, 2008
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      The SWTPc's have held up nicely over the years. I am glad it
      works. Thanks for the update.

      I forgot to mention in my earlier email that the Apple ][ restoration work
      by Evan, Joe, and Andy.

      Bill

      At 09:05 PM 4/1/2008 -0700, you wrote:
      >Bill,
      >
      > What I have done so far with the SWTPC 6800-based S50 system:
      >
      > Found Mike Holley's great site on the swtpc stuff,
      >without which I would have no progress to report.
      >ID'd all of the various cards, except one. Three 8K
      >SRAM cards. One newer 64K card which seems to be configured
      >to conflict with the other cards, so I am not sure it was ever
      >used in this system. Only has 8K installed, even though
      >that one card could replace all three of the others, which
      >are spec'ed to draw 1.5A each! I worked on the terminal first.
      >It didn't really need much. I added a DB-25 instead of the
      >ugly molex serial connector. (shielded cable for a serial
      >connection?) Did the same thing on the computer end.
      >Both cases already had holes for the DB-25, so it seemed
      >like a natural. Got the CPU card and one RAM card talking to
      >the terminal, after a little contact cleaning and resoldering
      >a few connections. The connectors are not gold, and are not
      >edge connectors, but fat pins on the MB and sockets on the
      >cards. They require an incredible amount of force to plug on,
      >so I added some extra support under the MB to keep it from
      >flexing too much. Was afraid it might get damaged. I added
      >a second RAM card, for 16K total. Keyed in a simple assy RAM
      >test which didn't find any errors. Downloaded 8K SWTPC BASIC
      >image from the web, and loaded it using the built-in monitor
      >program and a terminal program on a laptop.
      >Was able to type in a simple BASIC program and run it. (No
      >manual, so it took a little fiddling to figure out how to even do
      >that) I am trying to write a little assy program to fill the
      >terminal screen with some text for a static demo. Not working yet.
      >
      > Without a floppy drive, this system seems rather limited.
      >I have not played with the cassette interface. Read that it is
      >really slow. Runs at 300 baud. Woohoo!
      >
      > The serial baud rates are crystal-generated, but the CPU clock
      >is controlled by an RC network. Previous owner replaced fixed
      >R with a pot, so I can change the system operating speed with a
      >potentiometer! 1 MHz is the nominal CPU clock. (Similar to Apple ][)
      >
      > Bob
      >
      >
      >
      >
      >
      >--- billdeg <billdeg@...> wrote:
      >
      > > In addition to the museum room renovations, we also make progress
      > > with
      > > some computer restorations
      > >
      > > 1) Bob Grieb has reported progress with the MARCH SWTPc 6800, SWTPc
      > > terminal and cassette interface. I assume he'll let us know how it's
      > > going in more detail soon. He is working on this unit at his home.
      > >
      > > 2) Using the the MARCH Altair 8800 as a control unit, Bob Grieb and
      > > Dan Ragonti did some comparative diagnostics on my Altair 8800. It
      > > was productive to have two Altair 8800s to work on at the same time.
      > > I took a lot of notes and will post them on my web site soon. Dan
      > > ended up taking my Altair home with him for further study/fun. The
      > > next day Nick (donated the MARCH Altair), me, and Dan a terminal
      > > working with the MARCH Altair. (I brought a Teleray terminal for
      > > testing) The MARCH Altair has CUTTER and the Subsystem B card from
      > > Processor Tech. To-do - get a terminal for the MARCH Altair.
      > >
      > > 3) We have about 6 Apple ][e / Plus computers. We were able to get
      > > at
      > > least one complete working system. To-do - test all Apple ]['s plus
      > > the Apple //c, and //GS
      > >
      > > 4) The original version IBM PC 5150 - After taking apart the system I
      > > determined that there was at least one bad RAM chip in bank 1. It's
      > > a
      > > 64K Unit with an additional 64K RAM card - 128K. This 5150 is the
      > > first version with the black power supply, very rare. I hope to
      > > fully
      > > restore before September. Note - we have the original boxes, monitor
      > > and keyboard, DOS 1.1, etc. Very nice.
      > >
      > > 5) DEC - No work done other than take a peek at everything.
      > >
      > > 6) Other stuff - Waiting for future...
      > >
      > > Bill
      > >
      > >
      >
      >
      >
      >
      >____________________________________________________________________________________
      >You rock. That's why Blockbuster's offering you one month of Blockbuster
      >Total Access, No Cost.
      >http://tc.deals.yahoo.com/tc/blockbuster/text5.com
      >
      >------------------------------------
      >
      >Yahoo! Groups Links
      >
      >
      >
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