Re: Asteroids and 'wiggly' diagonal lines

----- Original Message -----
From: "Jess Askey" <jess@askey.org>
To: <vectorlist@synthcom.com>
Sent: Sunday, January 13, 2002 2:54 PM
Subject: Re: VECTOR: Asteroids and 'wiggly' diagonal lines

> I think someone else briefly mentioned this but if you have an mysterious
> invisible line of distortion then it usually means a bad bit output on one of
> the vector counters. I think they are 74LS191's? I had this problem once
> before, if the line is vertical then look in X counters and horizontal would be
> Y counters. Since the bit is faulty you can usually track it down by simply
> putting the game onto the crosshatch screen and then making sure that all
> outputs of the vector counters are pulsing with a logic probe. If one is stuck
> high or low, then you can make a good guess that that output is faulty (unless
> what it connects to is holding it steady).

I once saw an asteroids machine with huge gaps in the characters.
The gaps were horizontal, evenly spaced across the screen, and "warped" graphics
as they passed over these bad areas. No lines wanted to be in these
areas, they would be "jumped over" I suspect this was the same
problem mentioned above, but with many bits or a high bit being stuck.

Aaron H.

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Received on Sun Jan 13 16:13:52 2002