On Thu, 18 May 2000 technoid_at_cheta.net wrote:
> Most other-than-IO functions performed during I/O such as graphics, sound,
> etcetera on the Atari 8-bits utilized the fact that for 1 60th of a second
> the screen is not painted. While the 'vertical blank' was occurring you
> had several cpu cycles available. If you wrote very tight code you could
> do a lot in those few cycles. On the Atari this was accomplished by GTIA
> 'display lists' which are programs for the GTIA coprocessor.
>
> Can the Apple II be convinced to perform this feat? I have allways
> wondered but not passionatly enough to investigate about the Apple II
> series i/o scheme.
The Apple ][ has an address that you can monitor that tells you when it's
in the vertical blanking interval. People have done some neat stuff by
timing their code around the interval, such as mixing all three graphics
modes (text, lo-res and hi-res) on the same screen.
Sellam International Man of Intrigue and Danger
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Received on Thu May 18 2000 - 15:48:19 BST