Re: Apple II GS Question

[pubpc1@library.ucla.edu]

Brian Uhreen <bduhreen@spots.ab.ca> wrote:
>: In article mportune@telerama.lm.com (Matt Portune) writes...
>
>[snip]
>: >And yes, especially with a meg of cache on the RamFAST and the slot set
>: >to "fast" on the Zip, hard drive performance is SCARY.  What was our
>: >shift boot speed, Mitch?  I know mine is about 3.5 seconds from
>: >splash-screen to desktop and yours was a hair faster if I remember
>: >correctly.  (I'm still running at 14.33 MHz)   :)
>
>How, exactly, does the Zip accelerate the slot speeds?  Since I was
>under the understanding that you could not bypass the 1Mhz bus, does it
>simply shadow the slot area (of memory bank $e1 or something) into its
>cache???
>
>                Brian

Brian, I think you are confusing things just a little.  While you
can't change the operation of the Apple bus (which operates at the
theoretical maximum of 1MB/sec), you can change the way in which the
slots operate in conjuntion with the CPU.

On a non-accelerated GS, the GS CPU runs at 2.8MHz, but drops down
to 2.6MHz or 1MHz during various operations to maintain 8-bit
Apple II capatibility.  Specifically, when accessing the 128K of
slow RAM dedicated for Apple II emulation or non-shadowed video
or the expansion slots, the GS drops down to 1MHz.

On the Zip, you are given a choice.  You can set each slot to so that
the CPU does NOT slow down to 1MHz when accessing it.  Doing this
allows the Zip to maintain its fastest CPU speed (say, 15MHz) while
accessing the slots.  As you can imagine, setting a 5.25" floppy
drive's slot to accelerated speed makes it unusable, but setting a
hard drive controller's slot to fast makes the hard disk run faster.

-Scott G.