There is a brief appearance of a
PDP-12
minicomputer from the late 60s in one of
Forcefield's
experimental short movies. I operated it for them, and ran a little
graphics demo program that I had written that was basically etch-a-sketch
using two of the analog input knobs on the computer. (The PDP-12 was
designed for realtime lab use, and has a bunch of analog inputs, and
relay outs for interfacing with & controlling experiments.)
I wrote the graphics program as an experiment to learn the
low-level operation of the PDP-12. I wrote it using only the
front panel switches & lights. No operating system, and no
assembler. Just raw binary machine code. Luckily the 12 has
single instructions for doing things like sampling an analog
input channel, or outputting a point to the vector display, so
it was surprisingly short. Writing code, even a trivial little
graphics toy like that, at such a low level really teaches you
a lot about how computers function.
