[atari7800] Re: Paddle controllers??

  • From: "Dennis Debro" <dennis@xxxxxxxxxxxxxxx>
  • To: <atari7800@xxxxxxxxxxxxx>
  • Date: Sat, 19 Feb 2005 08:51:38 -0500

Hi Adam,

> Are we talking about timing problems during video DMA from the maria?

That's what I was thinking. I re-read the programming doc again and it
states that no time would be stolen when a DLI occurred. Is this true? What
if the DLI lasts too long? Wouldn't this affect the next line?

For instance, let's say you do have a DLI for each zone and the first DLI
runs too long and the second zone is being drawn. If I understand what I
read, the 6502 would be halted while the next line is drawn, then the DLI
for the second line would be called. But we never completed the first DLI so
its return position is still on the stack. It seems that if none of the DLIs
ever complete you could end up trashing the stack. Is this a correct
assumption or am I reading this info incorrect?

It does seem like paddles and/or the trak-ball could be implemented on the
7800 with good resolution though. I just wonder shat happens if the DLI
takes too long and runs into the next zone.

Take care,

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