19 Jun
2020
19 Jun
'20
8:58 a.m.
-----Original Message-----
From: Ethan Dicks <ethan.dicks at gmail.com>
Sent: 19 June 2020 15:44
To: Dave Wade <dave.g4ugm at gmail.com>; General Discussion: On-Topic
and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: Synchronous serial Re: E-Mail Formats RE: Future of
cctalk/cctech
On Fri, Jun 19, 2020 at 4:26 AM Dave Wade via cctalk <cctalk at classiccmp.org>
wrote:
Ethan,
Well some do, some don't. In general we avoided using it because we probably wanted to
set other signals,
However the first card for which I could find documents, the QBUS DPV11 has a configurable
clock on pin 24
http://www.bitsavers.org/pdf/dec/qbus/EK-DPV11-UM-001_Aug80.pdf
page 2-5 and 2-7. Its called "null modem" but you can see its connected back to
the clocks so you can test the interface.
Dave
Its been ages since I did this but looking here
DPV11
https://www.aggsoft.com/rs232-pinout-cable/RS232.htm
I see we have a transmit clock output on pin 24, transmit clock input on 15
and
RX clock input on 17.
So if on checking with a scope I have clocks on
24, I would try linking 24 and
15 on one side to 17 on the other side.
If you have only one clock running then that goes
to 15 and 17 on both
ends....
None of the devices I worked with in the 80s and 90s had clock available on
pin 24. I'm not saying none exist, but they weren't around in the era I was
doing this.
-ethan