Synchronous serial Re: E-Mail Formats RE: Future of cctalk/cctech

[Dave Wade]

> -----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:
> > 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,
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



> -ethan