[Coco] Coco3 warm start...
robert.gault at worldnet.att.net
Fri Nov 16 08:53:46 EST 2007
William Astle wrote:
> I know I'm probably not seeing something obvious, but there is a point
> that confuses me. I have been tracing the warm start process in the ROM
> and as far as I can see, the warm start process never leaves ROM mode. I
> know it must do so but I just can't seem to find the instruction that
> does it.
> In the cold start path, the ROM to RAM copy process leaves the system in
> RAM mode but the warm start path doesn't do the copy.
> Am I missing something obvious or is something obscure going on?
The code at $C000 is hard to follow and the tendency is to make false
The reset button will cause the CPU to jump to $8C1B which does force
the 32k internal ROM mode and jump to $C000. The critical test regards
this question is the code at $C0DE-$C0E5. $FFA0 is cleared which removes
the normal $38 block and replaces it with the lowest possible block
based on available memory. Then $71 is tested for $55. This test will
fail for Disk Basic but will pass for OS-9 and some other programs that
"know" about the Coco3.
Since the above test failed, memory is copied from ROM to RAM and the
system switched back to RAM mode.
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