The empty backplane slots on the left are used to connect the six cables needed to interface with the computer. The slots on the right are not used. The card with the DB25 connector is a home made version of a W070 that outputs standards RS-232 levels instead of 20ma current loop for a teletype.
Feel free to contact me, David Gesswein email@example.com
with any questions, comments on the web site, or if you have related equipment,
documentation, software etc. you are willing to part with. I am
interested in anything PDP-8
related, computers, peripherals used with them, DEC or third party, or