[Coco] Strange results reading the palette registers on Coco3

[Mark McDougall]

On 6/12/2011 8:54 AM, Robert Gault wrote:

> Anyway, the main point is that recent changes to the MESS source code had an
> effect on how the palette registers were read. Programs like my CER-COMP
> program stopped loading with an I/O error because the comparison above failed.

Why is your software checking the state of undefined/unmapped bits anyway?

> Looks like there is no practical way to fully emulate the Coco3 hardware in
> emulators regards un-mapped bits or bytes.

I think that's a bit premature at this stage, without further analysis. At 
the _macro_ level, the state of a computer is 100% deterministic.

As an example, IIUC there is Apple II software that makes use of floating 
bus values for pseudo-random number generation, and I seem to recall that 
even that aspect has been emulated _accurately_ in some emulators!

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"