PDP-1: THE BIRTH OF
DEMOCODING AND VIDEOGAMING


THE DISPLAY HACKS & SPACEWAR
AS DOCUMENTED ON MASSWERK.AT



The birth of democoding: the PDP-1 Display Hacks
The earliest examples of computer graphics coding emerged on the PDP-1, in the form of the so-called 'display hacks.'

The best known are Snowflake, a recursive drawing routine that produced intricate crystalline figures; the Minskytron, Marvin Minsky’s experiment in feedback loops and dynamic geometric transformations; and Munching Squares, a hypnotic bitwise graphics pattern that became a classic demo on many later computers.
The display hacks are pretty because of the Type 30 slow-phosphor tube, but also historically important: they marked the beginning of interactive computer art, foreshadowed the demoscene, and established computers as an artistic medium.

PiDP-1 construction Minskytron
PiDP-1 construction Snowflake
PiDP-1 construction Munching Squares
PiDP-1 construction Mapes' Graphical Fun

These programs are interesting to study, and that does not take much time: they are tiny in size. They are interactive, too: the TW switches will change their patterns & behaviour. See the links below.

Norbert Landsteiner reconstructed and documented them; his masswerk.at site contains many pages that are an absolute must-read for anyone interested in software archaeology and coding on the PDP-1.

A good entry point is Masswerk: Minskytron
The birth of videogames: Spacewar
Of course, PDP-1 graphics culminated in the first-ever computer video game, spacewar.

The definitive introduction to the game and its history is Masswerk: spacewar history
For the perspective of one of the authors, Graetz' 1981 review of spacewar, read Masswerk: 1981 review

Landsteiner went into a full analysis of the spacewar's code, in a series called 'Inside spacewar'. If you feel like developing PDP-1 programming skills, there is no better way than reading this: Masswerk: Inside spacewar

Landsteiner's PDP-1 studies were topped off with a backport of the first-ever arcade video game, Computer Space, to the PDP-1. Written in great detail, it is the perfect companion to the above: Developing ICSS: writing a PDP-1 video game

Another interesting program to look at - also its source code, is the backport of Pong by Hrvoje Čavrak. Also a much later game, and in its original, not even a computer game. But as its author, Al Alcorn, stated: directly inspired by seeing spacewar. PDP-1 Pong


This page is a pointer to masswerk.at, and that is all it needs to be. Everything about the history and the practical craft of PDP-1 programming is right there. One more recommendation is Levy's book 'Hackers'. Some chapters are online here . It adds the human-interest perspective of the PDP-1 saga, for a pretty complete understanding of PDP-1 history, and why the Hacker scene emerged. Graetz, one of the spacewar people, summarised it well: it's the World's First Toy Computer.