[Coco] CoCo Questions
robert.gault at worldnet.att.net
Sat Oct 28 23:23:45 EDT 2006
Phill Harvey-Smith wrote:
> Well You could have a small copying routine in ram that would disable
> interrupts, and then switch to map type 1 whilst copying, as then the
> other 32K would appear in the 32K-64K region, and could therefore be
> accessed at the same time, I would not have thought that this would have
> been too hard to arrange.
That won't work if you are using page swapping because the only RAM
available is the lower 32K and your ml program will get swapped out
along with any data it stored.
If you use type instead of page swapping, then you flip between 32K RAM
+ 32K ROM and 64K RAM. In this case you can have your swapping routine
and data in low RAM accessing information and/or a second program in the
upper 32K of RAM. For this to run two separate Basic Programs, you would
need to copy all of the 32K in upper RAM to lower RAM except where your
routine and communication data are located. That is a lot of overhead
for something practical.
In my opinion, programs of this type only became practical on the Coco3
where the swapping routines could be in constant DRAM and there was 512K
RAM to play with.
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