[antron]

Is there a way to get the TIA to end the horizontal blank a little early or late, to shift the playfield (or everything) 1 pixel left or right? I want to scroll the playfield one pixel at a time. Otherwise it will be very jerky (four-pixel jumps).

[Andrew Davie]

antron said:

Is there a way to get the TIA to end the horizontal blank a little early or late, to shift the playfield (or everything) 1 pixel left or right?  I want to scroll the playfield one pixel at a time.  Otherwise it will be very jerky (four-pixel jumps).

No. The finest playfield scroll possible is 4 colour clocks.
Cheers
A

[antron]

what will RSYNC (reset sync) do if called 3 colour clocks into a horizontal blank?

skip that line?

[EricBall]

antron said:

what will RSYNC (reset sync) do if called 3 colour clocks into a horizontal blank? skip that line?

RSYNC resets the TIA's internal horizontal position counter.

Now, if I assume this resets the counter back 0, the same point that WSYNC releases, this would be before the sync pulse. So hitting RSYNC during horizontal blank would probably generate a double sync pulse which would probably throw the TV for a loop, probably causing it to skip down to the next line or half line.

And even if the TV was able to sync properly, it also wouldn't change the object positions since the counters would still put it the same number of clocks after the end of the sync pulse.

[antron]

I will try it anyway.

thanks everyone

[antron]

I wrote to RSYNC 3 CPU cycles into a horizontal blank and this is what I got.

I took it a while to find the correct zero point again, so I decided to help it out by calling RSYNC again at the end of that line. It somewhat worked. Player 1 never got back on track, but that could be fixed. I am just trying to get the playfield into new positions.

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[Andrew Davie]

antron said:

I wrote to RSYNC 3 CPU cycles into a horizontal blank and this is what I got.

I took it a while to find the correct zero point again, so I decided to help it out by calling RSYNC again at the end of that line.  It somewhat worked.  Player 1 never got back on track, but that could be fixed.  I am just trying to get the playfield into new positions.

Very interesting indeed. Keep up the experiments and let us know the results. I'd suggest you post this to the [stella] list, too

Cheers
A

[antron]

Here it is called one cpu cycle (I think) into a h-blank.
I was hoping it wouldn't bounce as much, but it did. The *fix* doesn't help much.

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