PDP-8 on FPGA project & where is Hans Pufal?

From: "Philipp Hachtmann" Sent: Thursday, December 18, 2008 2:12 AM We have Hans' PDP-8 code from a few years ago, and John Kent did some nice work a year or so ago with us to clean up the build and to port to the XESS FPGA card. The code that Henk and I are using is derived from this code base. We haven't been able to reach Hans to get permission to redistribute, so there are just the three of us with the code (four, if you count Hans), as far as I know. I've got the code running FOCAL and other stuff in John's configuration, and the 8/i front panel is pretty much working in that configuration. There is currently a regression that broke the IOTs that FOCAL needs, so the more cool code examples don't work at the moment. Because the state lights (Fetch, Defer, Execute, WC, CA, Break, Pause) don't map well to Hans' machine states, and (more importantly) because we don't feel we can redistribute his code, I have recently started to implement a "direct coding" of the 8/i schematics in VHDL. That will hopefully give a "clock accurate" implementation of the 8/i. So far that's a bit experimental -- I haven't interfaced the memory or finished the timing generator, nor written the memory extension and timeshare code yet. Then again, I just started a couple of days ago :-). Sure, though unless we can get permission to redistribute, that doesn't seem too important. I'm sure there are other implementations out there. Maybe some more will come out of the woodwork :-). Vince