Re: Asteroids and 'wiggly' diagonal lines

At 15:54 13/01/2002 -0700, Jess wrote:

>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?

Yup, that's right.

>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).

Thanks, I'll give that a go ...... but I'm ashamed to say that my current
'logic probe' is a red LED with a 470ohm resistor stuck to one end
........... I guess that won't really be adequate in this case? :)

I really must get myself a decent logic probe when the finances allow it!
(or a reasonable one comes up on Ebay for the UK).

Thank you kindly for the tips - I think you might well have hit the
proverbial nail on the head. :-)

Regards,
Phil

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Received on Mon Jan 14 00:39:29 2002