The Plessey PDP-11 system has been expanded and enhanced and I even ported the RLV12 controller I built for my PDP-11 Hack to the Q-Bus. And surprisingly enough everything worked out quite smoothly and I got everything to work. But I also experienced, that it is and it will be even more difficult to get the necessary Q-Bus receivers and transmitters if I wanted to add more self made interfaces to the Q-Bus. And so I was looking into alternatives.

At the same time one of the 128kW memory boards of the Plessey systems failed. So I only had 128kW left which is not enough to run RSX-11Mplus.

That’s when I decided to start this project, a Q-Bus Memory Card for the PDP-11, which in the first version should omit those unobtainable DS8837 bus receivers, especially the SMD versions. It still uses the DC005 or C2324N bus transceivers, but they are not as rare as the receivers.

Eventually I will make another design which will also replace the C2324N with parts still in production. And then I most likely will also add a battery backup option.

For more detailed information please refer to the here .