RE: (Color Asteroids (was reproduction artwork...)

> Yeah, in fact, I have an Asteroids mod which lets you run Asteroids on
> a
> Wells Gardner 19K6403D color 3D monitor and plays with full 3D
> effects.
> Asteroids are in 2 different dimensions, ships another dimension,
> scores
> are on another monitor, shots fly out of the screen past your head,
> thrust rotates your house, etc. Just short two pins together-- no code
> changes.
>
:-) Oh, c'mon you people act like it's hard to do or something... ;-)

The only hard part was coming up with the idea-- I'm suprised nobody
else has done it. The reason I was keeping quiet is that I didn't want
anyone to beat me to it. ;-)

The hardware tells you exactly when the beam should be turned on and off
on the CRT. The game also has to load the "intensity" value for the
beam. Well, as it turns out, Atari used slightly different intensities
for a lot of stuff in Asteroids... So, if you take those 4-bit
"intensity" values and use them as an index for a color lookup table.
*Viola* color! Just takes something to generate a few bits of output to
make some resistor dividers for color outputs with some transistors.
Neat, huh? ;-) Seems like Asteroids only used 7 or 9 intensities very
often... To make the "flashing" color I had a counter that was
associated with one particular intensity value and instead of using a
lookup value for the color map, fed the outputs of a counter there
instead...

-Clay
Received on Fri Jul 31 17:12:01 1998