From Newsgroup: comp.sys.cbm
I have an MSDOS-like OS which currently works on the 8086,
80386 and S/3X0 (mainframes). You can see it here:
http://pdos.sourceforge.net/
I think it's too big to be ported to the Commodore 64,
and I've always wondered what options I have. I note
that the C128 has a Z80 coprocessor, and I was thinking
why stop there - why not have an 80386 coprocessor
so that PDOS/386 can run.
I was thinking that PDOS would sit outside of the 64k
address space, except for some stubs. A C64 emulator
for Windows could also load my 80386 PDOS kernel,
and then when PDOS needed to write to the screen, it
would either directly write to the C64 display memory,
or request the C64 emulator to do that.
The C64 user would be presented (on their normal
40*25 screen I think it is), an MSDOS prompt and
be able to do a "dir" of an emulated disk, which
would include a PDOS/386 micro-emacs executable
which used ANSI codes which are translated by
PDOS/386 into C64 character display buffer updates.
C64 executables would also reside on the FAT-16 disk,
possibly in ELF format.
The C64 executables would not be normal C64
programs, they would receive a callback function
on startup, and use that to request standard C90
services like fopen()/fread() so you have the full
C library available and can open any file on the
FAT-16 disk.
But when not requesting file services, or malloc(),
the C64 6502 code would have normal access to
the full C64 hardware (as provided by the emulator,
although theoretically a real machine could be
built too).
The callback functions would be 6502 stubs that
switch processor to 80386 using some mechanism
enabled by the C64 emulator.
Any thoughts?
BFN. Paul.
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