Re: 65C816 adapter for 6502 computers (aka Apple II)

["M. Pender" <mpender@hotmail.com>]

On 3/10/04 6:21 PM, in article WpN3c.135$i76.3008@attbi_s03, "Vince Briel"
<vbrielnospamme@comcast.net> wrote:

> Daryl Rictor has come up with a low profile 65816 to 6502 adapter that
> should work on the Apple II series computers. These boards are not tested
> but other people have done tests to get the idea working. The board is about
> the same size as the 6502 so there are no worries about space requirements.
> Check his website for more details. Also the 6502.org thread about this
> project. Imagine running a 65816 on a II+ or IIe! Volunteers are needed so
> check it out.
> 
> Daryl's web site information on this:
> http://65c02.tripod.com/conv.html
> 
> 
> 6502.org discussion thread:
> http://www.6502.org/forum/viewtopic.php?t=186&postdays=0&postorder=asc&start
> =0
> 
> 
> What do you guys think?

I'm not clear on the goal of the project.  If the goal is to run IIgs
software on a IIc/e then replacing the 8-bit 6502 with a 16-bit 65816 won't
accomplish that.  

If the goal is to enable the IIc/e to use the broader instruction set
available to the 65816, then its much easier to install a 65c802 in place of
the 65c02.  I used to do that with my Laser 128--there are even macro files
for Merlin and the Macrosparc assembler floating around (Asimov?) that I
wrote to allow access to the broader instruction set.

Note also that the timing of the 6502 is slightly different than the
65c02/65c802/65816.  Thus, the 65c02 is not a drop-in replacement for the
6502 on the Apple II or II+ -- IIRC it has something to do with the RDY
line.

- Mike