[Coco] Why so little mem for 4K Coco

[William Astle]

On 15-01-01 12:02 AM, Jim Gerrie wrote:
> Can someone tell me why the 4K Coco 1 only boots with 2542 bytes available?
> My 4K MC-10 boots with 3142 bytes available.  Is there any way to get a
> little more mem (besides clear 1)?  I have another 4K game (tetris) that
> will fit my MC-10 but not the Coco.

The data structures required by Color Basic use the first 1K. Then the 
display uses the next 512 bytes. That means you're down to 2.5K already 
maxiumum (2560 bytes). The only way to increase this is to move the 
display but the next available boundary supported by the SAM would be at 
address 512 (512 bytes lower in memory) but that doesn't leave enough 
room for the required data structures and buffers. My guess is that ROM 
in the MC10 has much smaller static data structures or it has a separate 
video memory somewhere allowing 512 bytes to be reclaimed for program data.