[Coco] CoCo3FPGA, FPGA Development, and GIME replacement

[William Astle]

On 2011-07-06 15:37, Stephen H. Fischer wrote:
> Hi,
> 
> Does the DICTATOR sound any better now?
> 
> I thought last night about breaking the 64K limit and hit a very thick
> steel wall.
> 
> Adding colors, a larger screen size and other features will run up
> against the 64K limit in several ways.
> 
> With a 6x09 processor it may not be possible to bypass it.
> 
> D.P. Johnsons's "Rocket", a 68000 added to the CoCo sounds like the idea
> that we missed out on because the number of people that signed up for
> was too little.
> 
> Software for a 6x09 based machine may already be at the limit of what we
> can do.
> 
> New hardware, Great, new software to support it, questionable.
> 
> SHF
> 
Getting past 64K is not terribly problematic as long as you have a MMU.
Running at a faster clock speed and having the MMU take effect
"instantly" upon updating it (like in the GIME) actually offsets the
extra code gyrations fairly handily. It's more whether you can clock the
CPU (and the rest of the system) fast enough to process the extra data
in a reasonable time frame that is the limiting factor I would think.

Granted, you'll take a performance hit when paging the video memory so
the CPU can mess with it, a hit that would not be present with a larger
address space, but it's certainly not impossible.