Chess

Chuck wrote: I played this a lot on weekends when I was the Cyber 73 weekend operator at Tektronix. This was under KRONOS rather than SCOPE. I believe that the console command was X.CHESS It used both CRT's, the left for a nice vector display of the game board, and the right for a listing of the moves made thus far, elapsed time, and for entering moves. I believe that the main program ran all of the chess processing, and that a PPU program communicated with the main program. The PPU took care of keeping the display updated. It offered, IIRC, ten different levels of play. The highest level I ever beat the machine at was level 4. Above level 4, it'd beat me quite easily. At level 10, I had no chance at all. The Cyber 73 had two main CPUs, and 20 PPUs (10 for each CPU). The CPUs were essentially 6600-design, with some enhancements for certain types of vector operations, as well as dealing with shared main memory. The load on the machine was pretty light on the weekends, and the operator didn't have much to do other than mount an occasional tape, or tend to the printer. The main program did load the machine a bit, but didn't seem to have any effect on interactive users. May have slowed down some big (run for a few days) circuit simulation jobs, but no one ever complained, and it was a good way to beat the boredom of sitting in a LOUD (lots of equipment), COLD (these machines like to run in a very cool room...even though they had their own refrigeration system for cooling) data center. I do recall once printing out a copy of the source. It was mostly FORTRAN-77, but there were some sections of assembly code if I remember correctly. I spent quite a bit of time studying the code. It was remarkably well-documented. Someone spent a lot of time on writing this program. The PPU code was indecipherable for me, as I never really learned much about the PPU instruction set. Sadly, I don't have this printout. I kept it for a while, but it ended up going to recycle during one of my moves. Bad me. I also wonder if there's any archive out there for it? There's a pretty good Cyber simulator out there that I've seen. Even a fairly modest PC today should be able to run this thing at least at "Cyber" realtime, if not faster. The machine did take a little time at level 10 once you got past the opening move book section of the program...machine moves would take from 5-10 seconds, to up to 90 seconds or so, but I never made it into level 10 deep enough to really exercise the machine hard. I think that the level setting simply put limits on the look-ahead tree branches. At level 10, it looked as far forward as the algorithms (and main memory) would allow. I also seem to recall there was some command you could put into it that would change the left screen from the view of the chessboard, to a "debug" view, that showed the evaluation processes involved in the machine determining its move. It was nicely organized to show a ranked listing of the best possible moves by its scoring algorithm, and below that it showed a text-representation of the board, with the machine making theoretical moves, then scoring the outcome. At the time, it was simply amazing the computing power that this machine had. How far we've come, and how much we've lost. Rick Bensene The Old Calculator Museum http://oldcalculatormuseum.com