[Coco] CoCo 3 I/O map

[William Astle]

A couple of notes for the GIME registers:

FF92 and FF93 also serve as interrupt status registers. Reading the 
register will have bits set for which interrupt source triggered the 
interrupt. Reading the register also resets the interrupt source state 
which means the state can only be detected on the first read after an 
interrupt occurs.

Otherwise, all registers in FF9x are write only. Reading them returns 
semi-random junk.

FFA0-FFBF are readable but only the lower six bits are valid when read. 
The upper two bits will contain semi-random junk.


Also, a note on the interrupt vectors (FFFx): On the coco1 and coco2, 
the contents of those vectors comes from the color basic ROM at BFFx. On 
the Coco3, however, the contents of those vectors comes from the top 16 
bytes of the 32K internal ROM (there is much information that states 
otherwise, but I have demonstrated this experimentally). In both cases, 
they are hard-mapped to ROM and cannot be changed regardless of any mode 
settings.

On 14-03-03 04:04 PM, Willard Goosey wrote:
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