check it out

From: Dave McGuire <mcguire_at_neurotica.com>
Date: Sun Aug 15 16:56:06 1999

On Sun, 15 Aug 1999, Lawrence Walker wrote:
> How did the old light-pens or the light-gun with Atari 8-bits work ?
>Weren't they related to this sensitivity of the CRT ?

  No, they worked the other way around. There was a light-sensing device
(photodiode, phototransistor, etc) in the pen or gun. The pen/gun control
circuitry "knows" where the dot from the CRT's electron gun is at any given
time...so when pressed against (fired at) the screen, during the next scan of
the screen the pen/gun control circuitry waited until it "saw" that the sensor
had been illuminated.

               -Dave McGuire
Received on Sun Aug 15 1999 - 16:56:06 BST