Re: Accelerator / VGA Graphics card

["Bill Garber" <willy46pa@comcast.net>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message
20031024175634.09411.00000038@mb-m28.aol.com">news:20031024175634.09411.00000038@mb-m28.aol.com...
> Sheldon Simms wrote:
>
> >On Fri, 24 Oct 2003 14:59:39 -0400, Charlie wrote:
>
> <snip>
>
> >> That makes sense and I like the idea of the 1MHz clock generating an
> >> interrupt on the card.  Wouldn't this free up the emulator to do other
> >> things (graphics) in between interrupts?
> >
> >Well yes, but it would probably do everything it needs to do and then
> >still be waiting around.
>
> Have you checked out how long the Pentium M requires to take an
> interrupt and restore state and return?  I'll bet that caches are much
> less helpful for this than you imagine, and _lots_ of cycles are needed.
>
> >> And even if there was nothing to do, from the little I've read about
> >> the Efficeon chip it drastically reduces its power consumption when
> >> it idles.
> >
> >So does the Pentium M. This sort of idling won't save too much power
> >though, because it wouldn't happen except when the card needed to
> >access the bus -- disk, DOC, flipping soft switches, etc. And
> >most programs spend only a small amount of time doing that stuff.
>
> And if you speed the processor execution up by a factor of, say,
> 25x, then the time spent doing these low-speed things does not
> accelerate, and the fraction of time doing low-speed things rises
> proportionately.
>
> For example, if a real Apple II running program X takes 10% of its
> time doing things like disk I/O, then even if the processor is
> accelerated infinitely, the program runs only 10x faster, since
> all of its time is now spent on disk I/O.

How about incorporating a Disk II image emulation mode,
whereby all necessary disks are loaded onto 800k or ramdisk
and then no slow-down is necessary. Would require a Smart
port device driver of some type.

Bill @ GarberStreet Enterprizez };-)
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