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

[John Kent]

Hi Little John,

That sounds very good !
If the pages are 8K then shouldn't you only need an 8 byte register file 
? ( 8 x 8K = 64K)

John

On 21/11/2010 7:23 AM, 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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