Steve You will find some additional write up of the DLV11J (M9740) in LSI11SeytemsServiceManualAug81.pdf page no ~270 et seq see e.g. https://bitsavers.org/pdf/dec/pdp11/LSI-11_Systems_Service_Manual_Aug81.pdf However, additional enlightenment is limited to the cab kit and MP part numbers, e.g. BC05C; which may yeild wire colours. As the M - E link is a ground strap to the differential receiver I would incline to using black wire (cf gnd line). I must have seen a genuine DLV11J cab kit about 40 years ago. However, I can recollect nothing but home brew substitutes / replacements thereafter; the color code being driven by the colors of stock 3-core cable. FWIW VanDamme audio cable makes nice 232 cables (very flexible), drain as ground : e.g. https://uk.rs-online.com/web/p/audio-cable/3658775 Finally, I shall relate a tale I was told in a bar. Once upon a time some a lady museum conservator was fussing over matching the paint color on Glen Douglas' tender https://preservedbritishsteamlocomotives.com/62469-glen-douglas-nbr-256-lne… An unkind soul pointed out that the paint she wanted to match was from the 1959 refit, and that the old mens paint could easily have been a different hue. Personaly, I would fuss over using the correct gauge of wire / crimps / housing and just make a note of the color scheme. HtH; Martin -----Original Message----- From: Steve Malikoff via cctalk [mailto:cctalk@classiccmp.org] Sent: 22 December 2022 03:16 To: cctalk(a)classiccmp.org Cc: steven(a)malikoff.com Subject: [cctalk] DLV11 M7940 SLU header wire colours? Sorry this post isn't about whether something is regarded as classic or not. I am almost done putting together a little 4-card Qbus machine using a H9281-BA card frame. Eschewing a piece of plywood, the frame, power supply, fans, Heeltoe POR board are all mounted on a clear acrylic A4-sized office 'In Tray' I picked up at a recycling centre. Hence I've named it PERSPEX-11 :) So.. For a DLV11 EIA serial connection, I am about to wire up a fly lead cable to go from an M7940 SLU (no dash version) 40-pin header to a DB25P. After finding the pinout on page 178 in the 1980 Interfaces Handbook, on header J1 I know only need the usual basic RS232 setup: J - Received Data F - Transmitted Data B - Signal Ground M to E loopback I have a blank 40-pin header shell and a pile of DuPont leads of all colours ready to slot into their respective locations in the header. I could use any colours but I'd really like to use the original colours for the above wires. So, the only wire colour reference in the handbook is for a J1 and J2 header DRV11 pinout on page 275. Pin B is Black, and Transmit is Red but Pin J Receive is marked as Orange/Ground, for that device. Also M and E don't have their colours specified for the loopback wire. I've also looked at the Gunkies 'DEC asynchronous serial line pinout' page which has the pinout but it doesn't mention the original wire colours sadly. Could someone point me to what colours the M7940 cable should be? Thanks for any help, Steve.