[Coco] Kinda off-topic, kinda crazy question about the Liber809

[James Igou]

Steven Hirsch <snhirsch at ...> writes:

> 
> On Fri, 11 May 2012, Theodore (Alex) Evans wrote:
> 
> > On 12-05-10 03:28 PM, Juan Castro wrote:
> >> How hard would it be to make a similar daughterboard for the 65C816?
> >> ("Liber816?") So one could do some 16-bit assembly programming and not have
> >> to forgo the Atari machine's native software forever?
> >
> > This is going to sound crazy, but the 65C816 is actually pin compatible with 
> > the 6502.  From what I understand there is only a 1 pin difference between a 
> > standard 6502 and the one used in XL series 8-bit Ataris
> 
> If that was true, every Apple 2 hobbyist in the world would have 
> back-fitted their machines.  You may want to take another look at the data 
> sheets.
> 
> Are you possibly confusing the issue with the 65C802? That short lived 
> chip was completely pin-compatible with the 65C02 - I have a couple here 
> that were used in Apple IIe boxen.
> 
> Steve
> 


Actually, comparing the 65C816 to the 6502,
they do seem to have a lot of compatible signals.
Boisy has posted the schematics for the Liber809.
Maybe its time to do a little research.

There IS one big problem:
Its the same one that effectively prevents a 3.58 MHz 63C09E 
>From being used in a board similar to the Liber809. 
Like the Color Computer, virtually all the clock signals in an 8 bit Atari
Are derived by dividing a single clock. So memory, CPU, and video timing are 
All interrelated.

You can't just increase the CPU speed.

BTW - This swap has been done by a Commodore hacker (don't you do web searches).

http://www.baltissen.org/newhtm/02to816.htm