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Re: 65816

Stephen Shaw <xstephenx@apple2.org.za> wrote:

> On Thu, 14 Jun 2001 18:18:00 -0400, Liam Busey wrote:
> 
> > I suspect that there aren't any 20mhz IIgs es around because the
> > available accelerators don't scale that well.
> 
> You might also be reaching the upper limits of the IIGS buss speed as well?

Accelerators on the Apple II do not and cannot change the bus speed,
since the master system clock is tied into everything, including the
video output.

They all operate on caching techniques, keeping a copy of data read from
real memory in fast RAM on the accelerator.

As far as I know, none of the 8-bit accelerators can handle DMA, but
both the ZipGS and TransWarp GS can.

At least one of the 8-bit accelerators provides enough fast RAM on the
card to replace the entire address space of the machine, with the
exception of I/O areas and video buffers.

In theory, the same could be achieved with the IIgs, as long as you
could get at least 4 MB of RAM (preferably more like 8.5 MB) on the
accelerator.