Well,
I've spent way too much time trying to read the ROM's from the
707/727....I got close but i came across a tricky requirement in order
for the ROMS to output data. The last problem makes it near impossible
to read the ROM's from a standard eprom programmer, even after I
solved the mixed-up address lines etc.
But that doesn't mean new ROMS cant be made. The protection Roland
used is burned into the functioning of the Mask ROMs, standard 27c256
replacements wouldn't have this requirement.
Also, some good news. I've been talking to Colin Fraser recentley & it
seems he has written a piece of software that will re-arrange the data
in a ROM .bin file, so that it can adapt to non-stndard address & data
line pin definitions. What this means is that a converter board won't
be necessary to burn new ROM's for the 707/727. All that one needs is
an understanding how the data is arranged in memory, and the 707
service manual gives a table which show's exactly how this is so. If
we get to the point where we want to create multiple banks (which
would be cool), we would have to settle creating new 707 & 727 banks
from samples of the machines.....reading the original ROM's is just
gonna be next to impossible.....
Seeya
Ryan