[Coco] Basic09 <==> 6809 interface.

[Jeff Teunissen]

On Sat, Aug 26, 2023 at 8:25 PM L. Curtis Boyle via Coco
<coco at maltedmedia.com> wrote:
>
> The problem with data modules for OS9/6809 (I don’t know if this applies to OSK) is that you have to re-verify the CRC each write to it, which can slow things down (or you shut CRC checking off completely). From appearances, the 6809 version is more meant as a read only file of data.

Technically you don't have to re-verify a data module each time you
modify it, only to allow a new program to link to it.

Two programs may both use a data module, with both of them reading and
writing it, and as long as no third program needs to link to that
module it will continue to work as a shared memory space.

The problem comes when a third program tries to link and fails the CRC
check. One thing you could do is send a signal to the process that
currently "owns" the module to trigger it to re-verify, then the new
program can join the party. This could be used as a sort of
authorization scheme for machines that are actually enforcing CRCs
without wasting a bunch of CPU time.