SWTPC 6800

Fred Cisin cisin at xenosoft.com
Tue Aug 9 14:09:06 CDT 2016

On Tue, 9 Aug 2016, Brad H wrote:
> I have a question though.. there have been a few times where I thought 
> the 6800 crashed but may not have.  In several cases.. I sent a large 
> loader file across and noticed errors coming through.. so I'd stop the 
> machine.  This was after teraterm said it had sent everything through. 
> Is it possible the serial port on my PC is still trying to send out 
> garbage for a while, messing up my connection to the 6800 until it 
> finishes?  I kept moving cards around but eventually it seemed to start 
> working after so many powerups and time had passed..

Do have any ACTUAL handshaking in the connection, or is it all bypassed to 
"go ahead, everything is ready, just send!"

If there is no FUNCTIONING handshake, then it could easily be as simple as 
the sender sending next byte before the receiver is ready for it.

Try adding another stop bit to the terminal software.

Sent from my Samsung device

-------- Original message --------
From: Brent Hilpert <hilpert at cs.ubc.ca> 
Date: 2016-08-09  9:49 AM  (GMT-08:00) 
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> 
Subject: Re: SWTPC 6800

On 2016-Aug-09, at 6:47 AM, Ethan Dicks wrote:
> On Fri, Aug 5, 2016 at 6:55 PM, Chuck Guzis <cclist at sydex.com> wrote:
>> On 08/05/2016 02:15 PM, Brad H wrote:
>>> 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.
>> Well, 110 bps is a bit on the slow side--great for teletypes, not so
>> much for video terminals.
> And I am not aware of any USB serial adapters that do 110 bps.  If
> anyone knows of any, post brand and model numbers.

It didn't do 110, but I chanced across one USB/serial adapter that goes down to 75 bps.
which fortuitously was just what I needed at the time for the model 28 teletype (with the appropriate gears) I was attempting to drive.

The 75 wasn't readily accessible, I had to go to a low level in the unix config code and try sequential factors in the
configuration for the rate, 75 being another factor of 2 down in the standard rate series 19,200 . . 9600 . . 1200 . . 300 . . 150 . .

Fred Cisin                      cisin at xenosoft.com
XenoSoft                        http://www.xenosoft.com
PO Box 1236                     (510) 234-3397
Berkeley, CA 94701-1236

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