Re: Replacing the 6502 with a faster chip

[mjmahon@aol.com (Michael J. Mahon)]

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/