Home
Dave

Blog
Archives
By Subject

Recent:

Cactus
Tree
Corn
Philippe Druillet
RCS Photos
WL-1B24
Wasp House
Castle
Barbarella
The Sands
Cat and Plant
De Futura Shirt
Usher 1928
Rambutan
Rotating Ethernet
Arcs
Raamat
Centrifuge Rotor
Resistors
Photomultiplier

Forcefield 12

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.