It's been a while since I've sent an update on the QSIC project and since work is currently on-hold while I'm in Alaska for my summer job, this is a good time. With the QBUS protocol pieces all working from the previous winter, last winter's work was to get some sort of storage medium working. SD cards seemed the right first choice so that was the task.
After a few months of staring at a state machine implementation and having nothing click for me, I set that aside and considered the idea of building a micro-coded machine. Noel and I kicked it around, came up with a design, he wrote up a micro-assembler and I did the Verilog. This was my first micro-machine but it worked out pretty well, I think. Anyway, we got the design running the SD card through its initialization sequence. Pretty pleased with that. The next step is transferring data blocks but I ran out of time. Also this winter I finally got myself a Github account and moved the code up there. Look for dabridgham/QSIC if you're interested. The webpage describing the QSIC project is http://pdp10.froghouse.org/qsic/html/overview.html. In related news, as we were working through the QBUS implementation Noel and I had a bunch of discussions about bus arbitration. I think we ended up with a decent understanding and so I decided to write it up for anyone else playing around with QBUS or Unibus designs. Yeah, I know, there aren't likely to be too many of us. Anyway, the paper is here: http://www.froghouse.org/~dab/papers/bus-arbitration/bus-arbitration.html There's a pdf version too but the formatting left off the overbar over Q in one section so it might be a bit confusing. Dave
