SWTPC 6800

Brad H vintagecomputer at bettercomputing.net
Sat Aug 6 18:00:20 CDT 2016

I am pleased to report I now have the 6800 alive and working.

I discovered one last error I made -- I assumed the cable to be used was a
null modem.  It was not.. what we needed was a 'standard modem cable' or
just straight serial.  I hooked that up, then looped the DSR/DTS pins on the
cable at the SWTPC end.. voila!  I can do all kinds of SWTBUG functions no
problem now.

For fun, I even hooked it up to my SWTPC CT1024.  I was pleased to see it
does communicate, albeit with lots of ? marks because the CT1024 is
configured for parity.  I guess I'll have to swallow hard, pull the board
(hoping the machine works again after) and change the jumpers to what the
6800 is expecting.  Then I can do a video of the two working together, which
as of yet has not been demonstrated on youtube. :)

Thanks to everyone for their helpful suggestions.  I'm very lucky this thing
wanted to work.  Off to do memory tests and test load some programs.. then
figure out how to bring back in the other mem boards.

-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brad H
Sent: Saturday, August 6, 2016 1:44 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
<cctalk at classiccmp.org>
Subject: RE: SWTPC 6800

Gahh!  So close!


The prompt is totally what should be appearing, at least initially.  But it
just keeps repeating itself over and over again and doesn't stop.

Notes:  I tried jumpering the DRC board to A000 properly this time, but no
dice.  So then I changed the jumper on the 'simple' MP-M board so that it
was A-0... plugged it in.. nothing.  Finally I took the second MP-M, with
all the fancy jumper wires and piggybacking nonsense.  Cannot tell how it is
jumpered or what for, but plugged it in.. boom!  Got that prompt.  Only one
problem.. it just endlessly repeats itself.  I can't type anything or stop

Also, I'm using the MP-C board.  After I got that prompt I thought I'd
switch the MP-S in but.. nada.  

I'm thinking (hoping) I've just got a wiring issue or something here that is
generating a continuous feedback loop.  But I don't know.  It could well be
that both the MP-C and MP-S are hooped.

But, that's definitely progress.

I'll post some high-res photos of the boards in that link asap.


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