[Coco] CoCo 3 patch question
robert.gault at worldnet.att.net
Mon Nov 24 23:23:40 EST 2008
Roger Taylor wrote:
> Does anyone know if the CoCo patches the Disk ROM if it's available?
As others have said, yes.
> I'm not sure what OTHER bytes are
> altered by the CoCo 3 patch routines.
The best way to study this is using the "Super Extended Basic
Unravelled" book. The Coco3 patch routines start at $C000. Part of what
happens is that the code looks for DK at $C000 in the DOS ROM. If found,
the external ROM is moved into RAM. Then the code looks for clues to
DOS1.0 or 1.1 and proceeds accordingly.
>This leads me to ask yet another
> question... how does the CoCo 3 (if it's patching Disk BASIC) deal with
> the other DOS brands?
The code can't and doesn't take into account third party DOS
modifications. However, there is so little patching done that it is not
hard to avoid these areas.
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