7701Re: [midatlanticretro] Restoration news from InfoAge.
- Apr 2, 2008The 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.
At 09:05 PM 4/1/2008 -0700, you wrote:
> 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 ][)
>--- 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.
>Yahoo! Groups Links
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