Sunday, February 17, 2008

Doubles, 2-Person Shooters:

I was daydreaming about one of my favorite computer experiences. Suddenly I realized that what happened then was not just my story; it's also an exciting new pathway for you. So here goes:
In 1966, working at Princeton, I discovered the Dec PDP-1. (If you follow the link, you'll see the graphical display sitting right next to the computer.) This machine was a revolution! Small by mainframe standards, it cost only $250,000. (In today's dollar terms, considering computer prices, that's about $27.75.) A friend explained to me how DEC managed to make a computer so inexpensively: it was simpler. He made this comparison:
When an IBM mainframe wants to send data to a peripheral, it sends a signal saying “I want to send you data!” The peripheral replies, “Who are you?” The computer says, “I'm the main processing unit!” The peripheral says, “Are you sure?” The computer says, “I'm sure. The peripheral says, “You can talk to me.” The computer says, “I really want to send you data.” The peripheral says, “When?” (and so on, and so on). In comparison, on the PDP-1, the if the computer wants to send data to a peripheral, it says, “Herecomesthedata!”

The PDP-1 was purchased with a federal grant to use in particle-tracking experiments. Images of particle tracks were recorded in a “bubble chamber,” and PDP-1 programs determined what kinds of particles they were. Occasionally. Because, really, the PDP-1 was very busy.

Most of the time, the PDP-1 played the game of “Asteroids.” Two people piloted space ships that could accidentally fall into the sun, bump into debris, or shoot each other. It was a very nice implementation. If you kept playing for 30 minutes without crashing, the stars in the background completed one revolution around the sun.

There were no computer mice in those days, but there were toggle switches that were normally used to patch data into memory. Programs could read those switches. In Asteroids, each player operated four toggles, to: turn left, turn right, accelerate, and shoot. It was a very exciting game, especially since, for most of us, it was the only known computer game in the Universe.

One day the powers that be decided to make us stop. They moved the graphical display, and bolted it into a rack where it could not be seen from the toggle switches. And that was that.

Only it wasn't. And this is the exciting part that you must take to heart! From then on, we played “doubles”. Each team had a navigator who sat in front of the screen and desperately shouted commands; and a pilot who operated the toggles. The doubles game was much harder to play, and it was ten times more fun.

What modern computer game can be played this way? Just think of one of those shoot-em-up games, where you might play doubles: you'd work the mouse, and your friend would scream at you where to move and where to shoot.


Unknown said...

As it happens, in 1965 I worked at the Rutgers Graduate Physics Lab's Bubble Chamber Group, where we too played "Asteroids" on a PDP-1. It was an indescribably great game... but what did we know... it was the only real 'game' we were aware of! Later we graduated to a PDP-6, but while we were learning how to deal with that machine, some of us were spending time at MIT... where real serious players spent _all_ night playing "Asteroids" on an original PDP-1, which was kept up & running so people could play "Asteroids"! said...

iodefinition, in the late 1960's, I worked at Applied Logic, which also used a pdp-6. There was a lot of contact between ALC and Rutgers people: Bill Easton, Bill Meier, Jim Bennett. Who are you? Please write to me at