Re: Asteroids Question

Chris Loggans wrote:
>
> To start a non-policy related thread... I've noticed a strange thing
> happening on a number of Asteroids PCB's that I have and I thought someone
> here could shed some light on it. I have about 10 working Asteroids PCB's
> and I've noticed this occur probably 6-7 of them. Every once and a while,
> probably once or twice a round, when you shoot an asteroid, it doesn't
> explode but collapses into a faint, but noticeable solid line. It is
> usually a vertical line about 2-3" long. While this is occurring,
> everything else on the screen is perfectly fine? I have tried this on two
> different machines/monitors and get the same results so it does appear to be
> PCB related. Has anyone else ever seen this or know why it is occurring?

Weird one.

Since it collapses into a vertical line, it is obviously a problem in the X axis
circuitry. But.. the strange thing is that it doesn't effect the whole screen, only
single objects. Since the DAC and everything past it (hereafter refered to as DAC+)
basically just follows the vector counters, the Im guessing that the DAC+ is all okay.
Esspecially since the 'invisible' position vectors arene't collapsing as well (which would
make the whole screen go into vertical line mode).
  So when it draws an Asteroid, the beam (turned off at this point), Moves to the center
of the asteroids position. All is okay here. Now the asteroid itself starts to get drawn
using the 'draw' instructions in the state machine which starts the vector position
counters going and the vector moving to draw a line of the correct slope and length. If
the X counter is not incrementing or decrementing, this exact problem would happen.
  Now Im not too familiar with the Asteroids vector gen, I know things are done
differently with the counters on it as compared to games after Tempest? But Im not sure
how exactly.
  Anyone know more?
Received on Thu Dec 2 12:43:42 1999