Den Wed, 18 Jul 2018 12:37:25 -0500 skrev Jim Brain <brain@jbrain.com>: > On 7/18/2018 3:59 AM, Michał Pleban wrote: > > Jim Brain wrote: > > > >> Well, it should not *HAVE* to be rewritten. It can, though, to > >> support the '816. > > If it's not rewritten, how will it access the DRAM when the 816 is > > used? > When the unit boots, it boots into 6502 "mode", where $0 and $1 > behave as before. Maybe I misunderstand the question. Yeah, and when switching to 65816 mode it can use a disk-loaded kernal in some other part of memory. Btw I know I'm feature creeping, but how hard would it be to add a mode where the video ram from bank 15 is seen at $8000, the rest is ram and some way of exiting that mode by accessing some address that is an I/O space of the original PETs? That way it would probably be rather easy to emulate a PET good enough to run most PET software. > >> On a real 6509, if you store $aa at $0 and read it back, do you > >> get $0a or $aa? > > It will read $0A. > > OK, thanks. That makes creating an 8 bit port version of the 6509 a > bit tougher, but maybe still doable. Are you thinking about access to 16MB instead of 1MB in 6509 emulation mode? I think that might need to have an enable/disable function as I'm sure there are software writing garbage to the upper 4 bits of $0/$1. -- (\_/) Copy the bunny to your mails to help (O.o) him achieve world domination. (> <) Come join the dark side. /_|_\ We have cookies.Received on 2018-07-19 23:01:55
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