On Sat, 25 Dec 2010, Jim Brain wrote:
My main concern was the BIOS. I can layout the board,
source the parts, and
construct the prototypes, but I'm only familiar enough with Z80 to code up
some extremely simple test programs. A Z80 BIOS would be way beyond my
capabilities, and a second version that works in conjunction with IO coming
from a C64 or C128 would be more complicated yet. I'll see what I can source
relative to the hardware design.
In the late 80's I was involved in the design and marketing (such as it
was) of a Z180 based coprocessor board for Apple 2 machines. You may be
able to leverage a lot of the CardZ180 BIOS code for use in a C= add-on,
since the cast of characters is identical (well, almost, but there's only
a small amount of stuff that's particular to '180 architecture).
If nothing else, it's a working example of how to split BIOS functions
across a Z180 guest and 6502 host. The original tool-chain was a wierd
combination of Microsoft M80 assembler and SLR linker, but I bet there are
Linux based cross-assemblers that can do the job nowadays.
Please drop me private e-mail if you want to have a look at it or discuss
further.
Steve
--