RE: C64 2 Mhz Hack
Date: 2001-02-26 03:46:17

There are several articles in Go64 detailing the wait stating necessary.

SIMMs are only used for the extra memory on the expansion board which goes
up to 16MB.  Wait states  can be as long as 8cycles.

Most of the time reads are from fast SRAM for the standard 64k and the extra
64k which shadows the roms.

The write cycles to the C64 are DMA based...

As some might know, i've been playing around with a core-emulator for the PC
in the hope of getting it be the 6510... To prove how valuable selective
mirroring is, consider this.  If all is mirrored, the emulator slows to
1.3MHz on K6-2/500 PC, If page 0 and page 1 are not mirrored, the core
emulator runs at 40MHz. If nothing is mirrored, the core will run at 66MHz.
(tests done with the bas-test program distributed with C64s). The problem
for the PC is ofcourse ISA I/O bus writes needed for transfering data
to/from the C64.

- Nick


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