SWTPC 6800

[Brad H]

RAM could certainly be an issue.  I had *tons* of bad RAM dogging me with my Digital Group Z80.  That took two weeks of testing to get through it.  I might just test out all this RAM in the DRC boards first and see if I can get away with just using those rather than bringing the soldered MP-M boards into the mix right now.

-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Dave Wade
Sent: Friday, August 5, 2016 2:42 AM
To: 'General Discussion: On-Topic and Off-Topic Posts' <cctalk at classiccmp.org>
Subject: RE: SWTPC 6800

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brad 
> H
> Sent: 05 August 2016 07:46
> To: General Discussion: On-Topic and Off-Topic Posts 
> <cctalk at classiccmp.org>
> Subject: RE: SWTPC 6800
> 
> 
> 
> Yes.. I tried 7 bits.. different parity settings, speeds etc.  
> Couldn't quite nail it down.  In every tutorial online for the 6800 
> being used with PC terminal, they go 8 N 1.. nobody mentions 
> specifically if you are supposed to use hardware or xo/off or nothing 
> though.  So that's another thing.  I'm also confused because some docs mention baud rate settings for the cpu board?
> I'm also not sure if bad RAM or bad TTL etc could be contributing to 
> just throwing out random junk too.
> 

If the data received is inconstant then bad RAM is a likely cause, ROM usually fails consistanly.

but as with all problem solving, Conan Doyle had it right when he said "after eliminating the impossible, whatever is left, however improbable, must be the solution"

Dave
> 
> Sent from my Samsung device
> 
> -------- Original message --------
> From: Dave Wade <dave.g4ugm at gmail.com>
> Date: 2016-08-04  11:33 PM  (GMT-08:00)
> To: "'General Discussion: On-Topic and Off-Topic Posts'"
> <cctalk at classiccmp.org>
> Subject: RE: SWTPC 6800
> 
> "Random Stuff" on serial ports can be a speed, data-bits, or even 
> parity mis- match.
> I assume you have tried tweaking these?
> 
> Dave
> 
> > -----Original Message-----
> > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of 
> > Brad H
> > Sent: 05 August 2016 06:58
> > To: 'General Discussion: On-Topic and Off-Topic Posts'
> > <cctalk at classiccmp.org>
> > Subject: RE: SWTPC 6800
> >
> > I think this 6800 is live but I am being dogged by my inabilities 
> > when it
> comes
> > to cabling.  I'm going to purchase a 'proper' db25 female connector 
> > and
> the
> > molex pins for the MP-S connector and solder it up.  I tried sort of 
> > using jumper wires to make it go.  When I turn the 6800 on, the PC 
> > terminal I'm using reacts by producing single or strings of random
> characters.
> > According to the SWTPC 'system checkout' stuff, if I get anything at 
> > all showing up on the terminal it usually means the 6800 is alive.
> > Based on
> the
> > notes written on the MP-S, I'm confident I have the correct baud 
> > rate and
> bit
> > (8) and parity (1) settings, but alas, doesn't seem to work.  When I 
> > ran
> into
> > this sort of thing with MSI 6800 it turned out the baud rate switch 
> > on the serial card wasn't correct, despite factory labelling.  That 
> > might be the
> case
> > here but not really sure how to sort it.
> >
> > -----Original Message-----
> > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of 
> > Paul
> Birkel
> > Sent: Thursday, August 4, 2016 12:29 PM
> > To: 'General Discussion: On-Topic and Off-Topic Posts'
> > <cctalk at classiccmp.org>
> > Subject: RE: SWTPC 6800
> >
>