On Thu, Jul 25, 2019 at 7:32 PM Douglas Taylor via cctalk <[email protected]> wrote: > > On 7/25/2019 10:11 PM, Glen Slick via cctalk wrote: > > On Thu, Jul 25, 2019 at 10:09 AM Douglas Taylor via cctalk > > <[email protected]> wrote: > >> I'm putting together a MicroPDP-11/23 in a BA23 box. Have the M8189 CPU > >> quad width board and the bulkhead cabinet kit, with two DB25 connectors > >> and switches to set the baud rate. On bitsavers the 'MicroPDP11 system > >> technical manual' shows how to set jumpers on the M8189 to allow this > >> cabkit set the baud rate, but only briefly mentions the cables needed. > >> > >> Does anyone here have a anatomically correct MicroPDP-11/23+ in a BA23 > >> box and can tell me how the cabling goes from the M8189 CPU board to the > >> bulkhead cabinet kit? > > I might have a console panel for an M8189 KDF11-B 11/23+. If I do, I > > couldn't find it the first couple of places I looked. Or maybe I have > > a console panel for an M7554 KDJ11-D 11/53, I forget which one, or > > both, or neither that I have. > > > > Anyway, back to the cable for the console panel for an M8189 KDF11-B > > 11/23+, isn't that just a 20 conductor ribbon cable that attaches to > > the 20-pin connector on console panel, then on the M8189 end it splits > > in the middle into two 10 conductor halves for the two 10-pin > > connectors on the M8189? > > > > To use the baud rate switches on the console panel the M8189 needs to > > be jumpered for external baud rate generation. The console panel > > contains a baud rate generator which feeds the baud clock into pin 1 > > of each of the two 10-pin connectors. > > Yes, it is a 20 pin cable at the bulkhead. I appears to be keyed so you > can't put it in wrong. The 10 pin connectors on the CPU board don't > seem to be keyed, so my uncertainty is about how the cable wires go from > the 20 pin bulkhead to each 10 pin connector. Is there something that > gives the orientation away? I thought maybe tracing the Rx Tx pins on > the DB25 connector to the 20 pin cable, then on to the 10 pin CPU > connector. These probably go straight thru without any diversion.
In the photos that I have found of the M8189 console panel there is a '1' just above the top right of the 20-pin connector indicating Pin 1. A trace can be seen leading from that pin to the baud rate circuitry. So that pin would go to Pin 1 of one of the 10-pin connectors on the M8189. Then 5 pins over from the Pin 1 on the console panel another trace can be seen leading from that other pin to the baud rate circuitry. So that would be Pin 1 of the second half of the cable going to Pin 1 of the other 10-pin connector on the M8189.
