[Coco] Any reason to put a 6309 in a Coco2?

[Arthur Flexser]

It was not the bank switching or other GIME registers that caused this
sort of incompatibility.  They were in the $FFxx area, which was also
unusable in the CoCo 1/2.  It was the vectors that were stuck in in the
$FEE0-FEFF range in the CoCo 3 that messed up lots of software,
particularly during memory size tests.

Art

On Tue, 30 Dec 2003, Kenneth Schunk wrote:

> Another incompatibility is the upper page of memory in 64K RAM mode. 
> This affected DEFT Pascal (and programs created with DEFT Pascal). The 
> DEFT runtime system switched off the ROM's and started looking for RAM 
> from the top of memory down. Since the top most page on the CoCo3 is 
> the bank switching registers (amongst other things), the RAM test ended 
> up crashing the CoCo3. A revised runtime library was needed to fix the 
> memory check so it didn't crash the CoCo3.
> 
> Ken Schunk
> 
> On Dec 30, 2003, at 3:37 PM, Theodore (Alex) Evans wrote:
> > A CoCo3 is not 100% CoCo2 compatible.  The main incompatibility is 
> > that most of the semigraphics modes supported by the CoCo1/2 are not 
> > supported by the CoCo3.
> 
> 
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