Re: 16-bit 6502 replacement bulk order : PCB schematics

[Rubywand <rubywand@swbell.net>]

"Michael J. Mahon" writes ...
> 
 ....
> 
> I thought that the 65C802 was _exactly_ a 65816 with 65C02 timings
> and a 16-bit address bus.  So, unless you have a plan to use the
> eight extra address bits of the 65816, what's the advantage?

     Mainly, it's easy to find fast, modern 65C816's. Besides, you may want
to use the extra address bits.


> 
> Put another way, the 65C802 should run all the 65816 software
> that fits in 64KB.

     That could depend upon which 64k as well as what the software wants to
check for in other 64k segments.


> 
> And if you want to directly address more than 64KB, you'll have
> to plug much more than a processor and a couple of glue ICs into
> the processor socket of an 8-bit Apple II, regardless of the model.
>
 ....

     Maybe. If access to 65C816 addressing capabilities is added, then,
adding extra IC's could be an way to expand address space and memory and,
possibly, add some interesting hardware. Or, you might add just a few IC's to
facilitate sensing and responding to accesses outside of specific 64k or 128k
areas.

     In general, if the sole objective is to be able to execute '802/'816
instructions in Apple II's which currently have a 65C02, then, sure, a new
batch of 65C802's would be nice. Since the '816 board is supposed to do the
job for about $20, it looks like a viable alternative.



Rubywand