On 5/18/2010 9:07 AM, Eric Rucker wrote:
current accelerators aren't really slowed down by the bus, because the accelerator can keep the CPU fed with data.
The accelerator has to slow down on certain I/O functions to 1Mhz due to timing sensitive operations, this is why there is so much logic on the TWGS and ZipGS. The TWGS actually has an LED that only lights when the accelerator is running. It flickers quite a bit during normal use. The only time its fully lit is when my IIgs decides to crash. Not too much I/O going on then. :)
The best thing to do would be to mirror all the system RAM in RAM running at the speed of the accelerator (cheap to do these days), but that only breaks the 2.6Mhz barrier between the RAM and CPU, I/O is still stuck at 1Mhz.