[Coco] Coco 3 Memory Map Questions

[Dave Philipsen]

I would have to agree with Darren.  However, since the chip select of 
the ROM is controlled by the GIME it is possible (although not likely) 
that the GIME could cause something other than the ROM contents at 7FFx 
to show up when the CPU addresses FFFx.

Dave


On 2/11/2016 9:35 AM, Darren A wrote:
> On Thu, Feb 11, 2016 at 6:04 AM, Robert Gault wrote:
>
>> Why bother doing these tests on real hardware? You should be able to do it
>> with an emulator such as MESS much more easily. Change the ROM content with
>> a PC editor file and start emulation even though the emulator might
>> complain about a "bad" ROM.
>>
>
> But why bother with the test at all?
>
> If you have an understanding of hardware, a review of the CoCo3 schematic
> would reveal that it simply isn't possible for the vectors to be mapped at
> $BFFx.  Look at how the address pins of the ROM are connected directly to
> the CPU address bus and then explain how the $BFFx locations could be read
> when the CPU is presenting $FFFx.
>
> - Darren
>