QSIC Update

David Bridgham dab at froghouse.org
Thu Jun 22 11:01:43 CDT 2017


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




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