Peter de Vroomen wrote:
I understand the 6502 and the 65C02 are pin for pin identical processors, but the 65C02 can be clocked faster. I understand too that all the 65-series processors share the same instruction set. If this is true, how hard would it be to upgrade the original 6502 with a 16-bit or 32-bit processor. The processor would then be able to use the lower 8-bits to drive 64K addresses, and the upper bits to give it an additional 64K or 128K.Do a Google search on 65c816 and 6502...The biggest problem is not hardware, but software.
Not exactly true. As Michael Mahon has explained (quite recently, and in far more detail than I could), memory access and video display timing are tightly coupled to the CPU clock. Check the archives of this newsgroup.
In the olden days, timings weren't implemented by using a timer/clock, but by executing a loop. This loop is going to be executed faster with a faster processor, which means all these kinds of loops in the software will have to be patched. And with only a binary rom, this is pretty tricky. You could disassemble the rom, but you would still have to fully document it before you know what's going on.
This is certainly correct in regards to Woz's diskette driver. Steve