Re: Replacing the 6502 with a faster chip

[robsgreenneon@startmail.ca (Rob Jones)]

mjmahon@aol.com (Michael J. Mahon) wrote in message news:<20040820034253.26080.00002251@mb-m28.aol.com>...
> Rob Jones wrote:
> 
> >While surfing the 'net, I found this adaptor
> >(http://www.6502.org/mini-projects/816conv/conv.html) that replaces
> >the 6502 with a 65C816 processor. I have not done any research on the
> >65C816, or for that matter the 6502 and its variants, but is there a
> >way to replace the Apple's 1MHz processor with something faster?
> 
> I expect you want to know if you can make an Apple II run faster.
> 
> The answer is yes, but it takes a lot more than a faster processor.
> The Apple II video generation is timed by the same clock that
> creates the processor timing, and the peripheral bus must
> operate at 1.0204 MHz for compatibility.  Some I/O cards
> also require precise code timing for correct operation, most
> notably the Disk ][ Controller for 5.25" disks.
> 
> So the trick is speeding up processing without changing the
> bus or video timing and only when speeding up will not cause
> other difficulties--not a simple problem.
> 
> You will need an "accelerator"--either a plug-in peripheral card
> like a TransWarp or SpeedDemon, or a module that replaces the
> processor with the equivalent circuitry, like the Zip Chip or the
> RocketChip.
> 
> As you might expect, these are all coveted add-ons for Apple IIs,
> so it may take a little digging and/or persuasion to get one.  ;-)
> 
> -michael
> 
> Check out parallel computing for 8-bit Apples on my
> Home page:  http://members.aol.com/MJMahon/

Is the 65C02 a pin-for-pin compatible with the 6502? I could very
easily make a 3X PLL (3MHz) to clock the "C" while keeping the bus at
1X (1MHz).