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

[Kenneth Schunk]

My mistake - that's what I get for relying on memory instead of looking 
at the source code. The original DEFT runtime code (PASBOOT) started 
checking for RAM at $FEFE. It was revised to start at $FDFE when the 
4.1 revision was done.

Ken
On Dec 31, 2003, at 12:38 AM, Arthur Flexser wrote:

> 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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