Found here:
http://www.pdp8online.com/bklatt/43.jpg
Digital Cables Handbook
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype:  TILBURY2591nw.johnson at 
ieee.org
On 2022-01-01 18:52, Ethan Dicks via cctalk wrote:
  On Sat, Jan 1, 2022 at 6:40 PM Chris Zach via cctalk
 <cctalk at classiccmp.org>  wrote:
  Regardless, I found a M857 board with a RS232
cable on it and BC01R-25
 on it. Was that for a pdp11/05 by chance? 
 I found this reference from the Cables
Handbook.  Sounds like it was a
 generic cable that probably worked with several devices.
 
http://www.pdp8online.com/bklatt/43.jpg
 My recollection was that the PDP-11/05 had a special 40-pin Berg
 connector off the backplane for the integrated Console SLU.
 -ethan