> -----Original Message----- > From: Ethan Dicks <ethan.di...@gmail.com> > Sent: 19 June 2020 15:44 > To: Dave Wade <dave.g4...@gmail.com>; General Discussion: On-Topic > and Off-Topic Posts <cctalk@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@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
