[Coco] Color basic 1.0, 1.2 differences.

[Robert Gault]

Phill Harvey-Smith wrote:
><snip>
> Ahh, but I was talking about plain non-extended color basic, version 
> 1.0, which seems in software to only detect 4K or 16K rams. Do you know 
> what version of Color basic is in there ?
> 
> Cheers.
> 
> Phill.
> 

The ROM is Color Basic 1.1 in my F-board Coco1. Looking at the source 
code for the 1.0 ROM, it reads a PIA at $A057 to determine 4 or 16K of 
RAM and sets the SAM at$A06A for 16K. However, at $A0AB the ROM has a 
routine which looks for the top of RAM by testing memory. It stops when 
memory can't be changed. I'm not sure what would happen if 32K or more 
of RAM was present, the SAM set for 16K, and data stored above $4000.

All you need to do manually if more than 16K RAM is present would be to 
STA $FFDD, STA $FFDA after the initial boot is complete. That will 
indicate 64K dynamic RAM. This could easily be put in a modified disk 
ROM or entered from the keyboard.