Forcing screenupdates

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dr beep
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Forcing screenupdates

Post by dr beep »

Is it somehow possible to force a next screenrefreshment before the ZX81 would normally do?

I now have a switching in screenrefreshment on Ghost Hunt, but when I do it 1:1
first screen 1 then screen 2 etc... it is too slow so you see the screen switching.

I was wondering when I would do more screens if the human eye wouldn't notice the screenflip anymore.
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Andy Rea
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Re: Forcing screenupdates

Post by Andy Rea »

i'm not sure how you are doing your 'page flipping' but i wrote a program that flips 8 pages (attached)

once the screen is drawn, detected by testing the low byte of the IX pair which changes from $81 to $8F (when normal nmi / int routines are running) when that nmi is turned back on for the bottom margin generation and user code starts running again, i then alter the D-file address in the system vars so that on the next frame a different d-file gets displayed.

here is a small program.

load the P file and do RAND USR 16514 (source included in ZIP)

Andy
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dr beep
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Location: Boxmeer

Re: Forcing screenupdates

Post by dr beep »

Thanks,

but I already have a routine that switch on every intrupt.

Could a call to #0070 help forcing a display?
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Andy Rea
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Re: Forcing screenupdates

Post by Andy Rea »

doing that would more than likely just mess up the display, the timing of it's genration is quite critical to keep it steady, as i'm sure your fully aware.

Andy
what's that Smell.... smells like fresh flux and solder fumes...
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