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Category: Mainframe

In 1960, the Digital Equipment Corporation DEC introduced their PDP-1 computer (Programmed Data Processor), a computer that would be a great influence for the development of hacker culture and computer games. As the first true minicomputer of the world, it was affordable for more than just the biggest universities and corporations. It was also the first commercial computer to be equipped with a CRT display, and controlled directly through a keyboard.

In 1961, a group of students and science-fiction fans at MIT started to program a very special, interactive demo for this new computer: Spacewar!, a spaceship duel with an amazing amount of detail. Featuring a previously unknown level of real-time action, two players each freely controlled a spaceship on a star background around a central star, which forced a strong gravitational pull on the ships. Players could rotate their ships, fire the afterburner, and shoot missiles. The goal was, of course, to annihilate the other player before getting hit by the opponent’s missiles or crashing into the sun. Various features like a correct display of the current real-world star constellation and a last-resort “hyperspace” button added to the game’s complexity and detail. DEC later decided to use Spacewar! to test new PDP-1 machines (because it allowed them to test most of the system’s functionality) and even shipped it with every sold computer, so Spacewar! was the first computer game to actually reach a certain level of popularity.

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Fortunately, the MESS emulator has PDP-1 support and is perfectly capable of running the original Spacewar! code. The CRT display even simulates the “trailing effect”. You first need to download and set up the MESS multi-system emulator. It is open-source, and available for all major operating systems. You can get Windows binaries and the sources directly from the project’s website:

The Official MESS Homepage

Computer Space Fan has a .ZIP archive with the Spacewar! paper tape for download:

Spacewar! page on Computer Space Fan

Installing the emulator and running the PDP-1 emulation should be straight-forward, the same goes for loading the spacewar.rim file into the paper tape reader. To have the PDP-1 read in the code from the paper tape, you now need to press [Ctrl] + [Enter] (this refers to the standard keyboard configuration for MESS.) The lights should start blinking. This is going to take a while, but after a couple of moments the game should instantly start. Player 1 uses the A, S, D, and F keys to control the ship, player 2 uses the cursor keys.