On Wed, 31 Oct 2001 firstname.lastname@example.org wrote: > Hi William, > > >Since it is intended to test ROM, RAM, and I/O, there is no point starting > >in the Ultimax mode and then switching. > > Except to maybe an idiot like me, if it has a black screen before and after > the cartridge gets inserted I am no wiser as to whether its something simple > like the Kernal rom or a reset problem :) Exactly. The KERNAL ROM routine executes one RTS instruction before jumping to the cartridge code. If the RAM at the top of the stack area (somewhere around $1f0-$1ff) is broken, executing the RTS may fail. As there are numerous other reasons for the screen remaining black, the starting method applied by the cartridge is not very useful. Marko Message was sent through the cbm-hackers mailing list
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