Sunday, June 03, 2018

Altair-Duino and TI Silent 700

The TI Silent 700 is a teletype using thermal fax paper.  It's light weight (compared to many teletypes) and fairly quiet.  I picked up a 703 on eBay.  When I got it, I discovered that it had the "high speed" package installed (that's means it's 1200 BPS instead of the default 300 BPS).


When I tried to hook it up to my Altair-Duino, I found that the DSR to be asserted or it doesn't think that it's online.  I had a choice between cannibalizing one of my serial cables, or making my own.  I decided to make my own.

I found a place online that sells DB-25 connectors and bought some male and female connectors.

The Silent 700 has a female connector.  So I took one of the male connectors and started on that end.


I looped back DSR/DTR and CTS/RTS (not known if that's needed, but I did it just in case). 
RTS/CTS are pins 4 and 5.
DSR/DTR are pins 6 and 20.

A co-worker told me about "security wire".  This is nice stuff for my projects.  4 wires wrapped in one cable.  The stuff that I got was solid, making it easy to solder into the DB-25 connectors.

I connected wires from pins 2, 3 and 7 (Transmit/Receive/Ground) of the Silent 700 to pins 2, 3 and 7 on the other end of the serial cable that I was creating.  One thing that I learned is that the pin numbers on the female end are opposite the numbering on the male end.



I also needed a DB-25 to DB-9 adaptor to connect the home-made cable to the Altair-Duino.  I probably should have gotten DB-9 connectors instead, but I wasn't thinking and I had the DB-25/DB-9 adapter laying around.

The problem that I ran into was that I soldered pin 1 on the Silent 700 side to pin 1 on the other end.  The DB-25/DB-9 adapter linked that to pin 2 for some reason.  De-soldering the pin from the Altair-Duino end solved that problem.

I won't go into setting up the Silent 700.  It doesn't support 8-bit communication.  I set it for 7-bit, even parity.  Then I went through putting those settings into the Altair-Duino through their instrtuctions (https://www.altairduino.com/2017/06/03/serial-device/).

And I now have a new retro-computing toy to play with.

3 comments:

LeftyX said...

Yeah, the pinout of the DB9 is not the same as the DB25:
http://wilbo666.pbworks.com/w/page/49320712/RS232
I just picked up a Silent 703 myself and look forward to using it!

LeftyX said...

How did you determine that its 1200baud? Very curious! I thought that needed a double printhead of some sort. Mine doesn't have that.

Ron said...

My Silent 700 came with a manual. So I went by that. I was pleasantly surprised that my Silent 700 had the "high speed option".

As a test, I hooked it up to my PC, fired up a terminal program and just typed something to see if it came out of the other end.