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.
In <200005181628.JAA12478_at_islay.ssl.berkeley.edu>, on 05/18/00
at 03:54 PM, "Eric J. Korpela" <korpela_at_albert.ssl.berkeley.edu> said:
>I don't think this is particularly a problem on the Apple ][ series.
>IIRC, all I/O is CPU intensive, so giving up the CPU during I/O will
>likely cause the I/O to fail. Am I getting old? The details of the Disk
>][ interface
>are only faintly registering on my brain. Wasn't the input a bit at a
>time with a software wait between bits, or am I confusing that with the
>tape interface with its half-hardware/half-software 1-bit ADC?
>Of course, none of this is a concern with cooperative multitasking of
>BASIC programs but if someone implements an interupt generator on a ][
>for multitasking purposes, it could become a concern.
>Eric
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Received on Thu May 18 2000 - 14:54:40 BST