[Coco] Assembly GIME programming...
zmerch at 30below.com
Mon Jan 23 14:00:33 EST 2006
Rumor has it that Robert Gault may have mentioned these words:
>The high resolution text screen is located at $6C000-$6E000 if created by
>the Coco ROMs.
Yup. My problem is with what I'm doing, I can't use the CoCo ROMs. ;-)
> If that is the region you want to access, first decide where in your 64K
> of RAM you want it to appear, use the appropriate MMU registers for that
> RAM region, make sure that $FF90 is set for Coco3 mode and the MMU is
> enabled, and make sure that the IRQs are off when moving around memory
> until it is reset.
I got that far - I got the machine out of CoCo2 mode, got the 80-column
screen set & mapped in $6C000-6DFFF into an unused portion of memory --
what I don't know and can't seem to find is how to tell the GIME where I
want it to use video RAM from - as it seems it defaults on boot to thinking
it should start at $70000 (as I can see the text at $70400 in the 80-column
I went thru the CoCo3 TechRef that I have & Sockmaster's GIME page on the
'net, and other than my sheer stupidity (which is certainly possible! ;-) I
can't seem to find what registers tell the GIME where in RAM to start the
80-column Video RAM. :-/
When I get home, I can post the assembly code I have so far...
Roger "Merch" Merchberger
Roger "Merch" Merchberger | "Bugs of a feather flock together."
sysadmin, Iceberg Computers | Russell Nelson
zmerch at 30below.com |
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