my first computer, game of "life"

From: dave dameron <>
Date: Fri May 29 02:50:53 1998

I first discovered digital logic and TTL IC's about 1973, and wanted to
build something not trivial with them. The project I chose was John Conway's
game of "life" as described in Martin Gardner's Mathematical Games in
"Scientific American"
I ending using a 32x32 element grid using 2 (then expensive!) 2102 rams (No
A or other suffix then) I would calculate one generation from one ram and
write to the other. I used about a 60kHz clock and 74193 counters to
generate the addresses. The clock went to a decade counter and the first 8
states generated +/- x and y clocks to visit the 8 neighbors of a given
cell. If the cell was a "1", another counter was incremented, number of
neighbors. The 9'th state was at the given cell.
The rule was then used: Neighbors =2 and cell active, or Neighbors = 3, then
the new cell was active, otherwise it was not. The 10'th clock wrote the
cell to the new generation (the other ram). Thus 10 clock cycles were needed
for each cell, or 10240 for each generation. This was much faster than a
later 4MHz Z-80 program!
I displayed the results on a 5 inch oscilloscope, using 555 timers with PNP
transistor current sources to charge the timing capacitor, for x and y ramp
or deflection waveforms. This was straight out of a National Semiconductor
databook. The refresh rate was about 60Hz. The "load" signals for the
74193's was used to write data into locations from address switches. Finally
3 7490's and 7447's displayed the generation number on 7 segment displays.

It was fun to watch the generations flash by. The total number of IC's was
about 35 + 6 for the generation counter.
Received on Fri May 29 1998 - 02:50:53 BST

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