DEC bus extender card

Extender cards for DEC busses seems to be quite rare, but are a useful tool for checking and repairing cards. It is however no problem for getting the parts for such a card and create it yourself. As DEC used the same connector for the Unibus and Q-bus, the extender should work for both.

The adventure starts with getting the specific parts from Douglas Electronic Inc.. I ordered a 6-DE-11 board and a 72-125C-EL.

The connector has all the contacts for the DEC boards, and no contacts where the slot has to be. As the connector is somewhat wider than the board, it is a good idea to install a slot.

Most sizes are in millimeters. The prototype slot I made is from a spare bit of vero-board. This is 1.5 mm thick, the width of the connector is 2mm. Some tape fixed this. The intention is to glue it in place, so the final slot should not have any tape.

Trying the extender card in my Minc-11 exposed another problem; the connector ears interfere with the cage. So the ears had to come off. Probably the best solution would have been to order the connector without ears: 72-125C-NL.

The final aluminium slot installed. 2mm is just the right thickness.


Last update: 2014-09-09