[Coco] Coco 3 Memory Map Questions

[Darren A]

On Tue, Feb 9, 2016 at 1:49 PM, Arthur Flexser wrote:

> ...how can you tell which is determining the hardware vectors,
> without burning a replacement ROM that modifies some bytes at one address
> or the other?
>
>

Actually, the design of the CoCo 3 would not permit the mapping of the
vectors to $BFFx.

On the CoCo 1 and 2 this happens because the SAM produces an S0..S2 value
which selects the Color Basic ROM (A000-BFFF) for the vector addresses.
The CoCo 3 has only the single 32K ROM, and the GIME doesn't control or
modify the CPU address bus which is wired directly to the ROM.

- Darren