The PONG Game

Ole Caprani,
Computer Science Department, Aarhus University,
ocaprani@cs.au.dk

Last updated 27.9.14.

PONG is one of the ealiest computer games where sound was added deliberately to the game, [1]. The sounds can be heard in this video clip from a game of PONG, [4]:

PONG or more accurately Atari PONG, was created by Alan Alcon. He did it as a training exercise assigned to him by Atari founder Nolam Bushnell, [1]. In an interview, [2], Allan Alcorn describes how sound was added to the game:

"So I just tried to make the game better and better, and at the end of the thing he (Nolam Bushnell) said 'you've got to have sound.' Oh okay, well I'm over budget and three months into this thing and Nolan said 'I want the roar of a crowd of thousands.' Cheers, applause. How do you do that with digital circuits? Ones and zeroes? I had no idea, so I went in there that afternoon and in less than an hour poked around and found different tones that already existed in the sync generator, and gated them out and it took half a chip to do that. And I said 'there's the sound - if you don't like it you do it!' That's the way it was left, so I love it when people talk about how wonderful and well thought out the sounds are."
There are three sounds in PONG:
Ball hit wall.

Ball hit paddle.

Player miss ball, point to opponent.

The waveform of all three sounds is the square wave, apparently the waveform generated by the sync generator. E.g. the paddle sound looks as follows:
The duration and frequency of the three sounds are as follows:
  • Wall sound: duration 16 ms, frequency 226 Hz.
  • Paddle sound: duration 96 ms, frequency 459 Hz.
  • Point sound: duration 257 msec, frequency 490 Hz.
The musical interval between the wall and the paddle sounds is 459 Hz/226 Hz = 2, i.e. an octave. Since this is the most harmonic musical interval, this choice results in a pleasant sequence of tones when the ball bounces of the walls and paddles for a while. The interval between the point sound and the paddle sound is a little more than a semitone, 490 Hz/459 Hz = 1.067. This means that the point sound is highly disharmonic with respect to the other two sounds and this together with the longer duration makes the point sound stands out.

Maybe Allan Alcorn was just lucky that afternoon when he "found different tones that already existed in the sync generator" or he had a pretty good intuition for sounds.

References