I've definitely got an MP-B.
What I'm thinking is I'll use one of the socketed 16k boards and go through the
RAMs to make sure I have good. But I'm having trouble understanding how to set
the jumpers to get the addressing to A000. I thought I had that by the guide
for the ram on the swtpc site (it's a Digital Research board). The machine
only gets animated when that weird piggybacked mpm board is plugged in.
I suppose if there are bad RAMs on the DR board that'd do it though.
Brad
Sent from my Samsung device
-------- Original message --------
From: Chris Elmquist <[email protected]>
Date: 2016-08-06 7:10 AM (GMT-08:00)
To: "General Discussion: On-Topic and Off-Topic Posts" <[email protected]>
Subject: Re: SWTPC 6800
Simplifying the machine configuration can help too. You should only need
MP-A (CPU), MP-S (serial interface) and MP-M at $A000 if you have the
SWTBUG ROM. It only needs 128 bytes of RAM at $A000 so an unexpanded
(4K) or partially populated MP-M would be sufficient.
If you have MIKBUG, then you need MP-C instead of MP-S since MIKBUG does
not know how to talk to MP-S.
Removing all the other cards temporarily could eliminate conflicts due to
addressing, failed components, etc.
With this minimal configuration, you should be able to get SWTBUG's "$"
prompt. MIKBUG will prompt with "*".
Also, check which backplane board you have. Depending on vintage, you
may have MP-B or MP-B2. MP-B2 allowed the I/O block address (normally
at $8000) to be changed. If you have MP-B2 and someone has customized
the machine, then there will be more to figure out regarding where the
I/O is really located, what the monitor ROMs expect, etc.
http://www.swtpc.com/mholley/MP_B/MP_B_Index.htm
http://www.swtpc.com/mholley/MP_B2/MP_B2_index.htm
Chris
On Friday (08/05/2016 at 10:47PM -0700), Brent Hilpert wrote:
> 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:
> http://www.swtpc.com/mholley/HiTerm/Test6800_Index.html
> he does mention RAM needed at A000 for the BUGs, as Chris and I have been
> saying.
>
> 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 <[email protected]>
> > Date: 2016-08-05 3:55 PM (GMT-08:00)
> > To: "General Discussion: On-Topic and Off-Topic Posts"
> > <[email protected]>
> > 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-Cable-Wires-Multicolor-K-/262158878688?hash=item3d09e307e0:g:B-MAAOSwwE5WVLR6
> >
> > Search on "female jumper wires"
--
Chris Elmquist
