From: Ullrich von Bassewitz (uz_at_musoftware.de)
Date: 2002-11-28 22:10:19
On Thu, Nov 28, 2002 at 09:16:42PM +0100, Ullrich von Bassewitz wrote:
> The COP vector at $FFF5/$FFF6 is unused. It needs special hardware to be of
> any use. The new BREAK vector at $FFF7/$FFF8 would be a problem, but since
> normal code does not have BRK instructions, this vector will never be used.
> The new BREAK vector will NOT collide with the kernal jump table (the last
> byte of the kernal jump table is at $FFF5). The 4 bytes at $FFF6 are unused in
> the C64 kernal, and I would assume that the CMD kernal for the SCPU has a
> valid BREAK vector in that location that is routed to the indirect kernal
> vector. I'm not sure about this, but since the space where the vector resides
> is not used anway, it would have been plain stupid not to do so.
Seems I have been wrong here, sorry. The new vectors are in the $FFEx range.
However, I'm definitely NOT setting up the new IRQ vector in Elite 128
(checked that twice), but the code runs on the SCPU. Is it possible that the
modified kernal gets this right somehow? If not, maybe it's magic then:-)
Regards
Uz
--
Ullrich von Bassewitz uz_at_musoftware.de
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