[Coco] What would a CoCo successor have to have as a minimum?

[jdaggett at gate.net]

John

I believe that Sockmaster's design for 80Meg and above uses FF96 and FF98  to expand the 
memory addressing. 

james

On 20 Nov 2010 at 14:23, Little John wrote:

> What my son and I have done as far as extending CoCo 3 memory was to map 
> register files (or dual port SRAM) at $FF80-$FF8F. These serve to extend the 
> MMU to 16-bits. For example, $FFA0 = LSB,$FF80=MSB and so on.This extends 
> the coco 3's RAM capacity to 512M or 65536 8K blocks, while remaining 
> compatible with existing software. Using the Video Bank Register (the one 
> designed by disto to bank the memory as 512K banks for the GIME's video 
> circuit) allows 256 512K video banks. So the video can be placed in any 512K 
> bank within the first 128Meg. The CPU can access the entire 512M as 8K 
> pages. Although the design is complete, it has yet to be prototyped and 
> tested.
> -JohnT-
> ======
> 
> 
> > There is flash memory on the DE1 board and there is 8MBytes of SDRAM which 
> > to the best of my knowledge is not used.
> > Access to extended memory can easily be achieved by mapping in another 8 
> > bit page register in I/O somewhere to extend the memory.
> > This would remain backwards compatible with the CoCo3 as the register 
> > would not need to be modified for existing programs.
> >
> 
> 
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