SWTPC 6800

Brad H vintagecomputer at bettercomputing.net
Sun Aug 7 16:40:11 CDT 2016

Yes I believe $A000 is covered by that heavily modded MP-M board.

I think the machine is basically working optimally (except for the odd time
I power up and it gives me garbage, not sure what that's about.. have to
fiddle with boards a bit and then it's fine again).  I ended up successfully
loading TSC Basic and making little programs in it.  I tried the Altair
BASIC with the special load file they give you but all it does is spill
stuff into the prompt.  

I've seen a video where the fellow loaded it, and then somehow entered a
command of MM in the process of setting certain things up to run it.  But if
I hit M it just takes me straight into changing a register the usual way.

Basically I think I have to educate myself a bit here on loading, etc.  I'd
love to find out more about this Newtech sound card too.. I've seen it in
use in some videos but strangely no documentation on it at SWTPC.COM.

-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brent
Sent: Friday, August 5, 2016 10:47 PM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: SWTPC 6800

Do you have some RAM at $A000+ yet?
That's all that should matter as far as required RAM goes.

Presuming this is the holley page you were referring to:
he does mention RAM needed at A000 for the BUGs, as Chris and I have been

Without RAM there there's no stack for return addresses for subroutines
executed in the BUGs, so execution could head off to wherever.

On 2016-Aug-05, at 10:23 PM, Brad H wrote:
> Okay so.. I decided to try the MP-C board out, just for kicks.  No change.
> Then I decided to add one of the RAM boards.. the next one up in
addresses.  Got a little bit when I powered on.  Added one of the old MPM
boards.. one that has memory chips all piggybacked on one another.  Now when
I powered up, the system was sending four or five characters at a time,
linefeed, four or five characters at a time, linefeed ad infinitum.  I added
the final MPM board.. zero.
> So.. I think we do have some ram problems.. most likely.  I'm thinking it
would be easiest to concentrate efforts on the socketed RAM boards.. test
all the RAM out.  I'm going to read up on addressing and try to understand a
bit better what is going on.  I'm thinking maybe I need to reconfigure the
addressing on one of the boards to match whatever that overstuffed MPM board
is set to.
> Until I get an oscilloscope.. fooling around is about all I can do here.
> Sent from my Samsung device
> -------- Original message --------
> From: Chuck Guzis <cclist at sydex.com>
> Date: 2016-08-05  3:55 PM  (GMT-08:00)
> To: "General Discussion: On-Topic and Off-Topic Posts" 
> <cctalk at classiccmp.org>
> Subject: Re: SWTPC 6800
> On 08/05/2016 02:15 PM, Brad H wrote:
>> I think I will have to figure out how to do that.  Additionally I 
>> have one of those PC based oscilloscopes on the way.  I don't know 
>> how to use them 100% but I'm about to learn I guess. :)
>> I have one more question for you guys -- I have a few CT-1024 
>> terminals and would really like this system to work with one of 
>> those.  However, all of the CTs are quite delicate and are set I 
>> think for 7, E, 2 @ 110 baud via soldered jumpers.  I'm a bit 
>> reluctant to try pulling them apart to get in there and fix that.  Is 
>> there a way to change the parity, etc settings on the SWTPC to match 
>> the terminal?  Is it necessary?
> Well, 110 bps is a bit on the slow side--great for teletypes, not so
> much for video terminals.   But you'll have to change the hardwired
> jumpers--the UART used in the CT1024 is not software-programmable.
> If this were my unit, I"d probably solder some pins into the pad holes 
> and then either use slide on jumpers or wirewrap to set the 
> characteristics.  That way, when changing things around, you won't be 
> stressing the PCB.
> Something like this:
> http://www.ebay.com/itm/10PCS-20CFemale-to-Female-1-Pin-Plug-Jumper-Ca
> ble-Wires-Multicolor-K-/262158878688?hash=item3d09e307e0:g:B-MAAOSwwE5
> Search on "female jumper wires"

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