cr1901 changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, CD/floppy disk theory of operation, and the 68k CPU are also on-topic. Channel logs: https://libera.irclog.whitequark.org/~h~yamahasynths
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<Lord_Nightmare>
D-50 uses a weird MCU as its main cpu
<andlabs>
NEC uPD7850 which is like the fourth horse in a two horse race when it comes to 8-bit MCUs
<andlabs>
but it is used in a bunch of stuff from the 80s
<andlabs>
from the perspective of yamaha synths the Korg synths that use a YM2164 also have it
<Lord_Nightmare>
do we know how to get the internal ROM out of those?
<Lord_Nightmare>
another thing is the d-50 has two other "mcus", the chorus and the reverb one
<Lord_Nightmare>
the reverb one might be an older/more featureful, ?internal rom? version of the roland/boss reverb chip used on the mt-32 and other la32 stuff
<Lord_Nightmare>
with the reverb program in mask ROM
<Lord_Nightmare>
the chorus one i know less about
<Sarayan>
there's a programmable reverb chip in the mt#@?
<Sarayan>
mt32?
<Sarayan>
I thought it was a fixed-function gate array thingy?
<Lord_Nightmare>
its fixed function but it uses these little 256 byte programs from a dedicated ROM
<Lord_Nightmare>
its i guess technically a dsp, but one which can't do conditional jumps? I think?
<Lord_Nightmare>
sergm reverse engineered it to some extent
<Lord_Nightmare>
and we have a bunch of logic analyzer traces of it
<Sarayan>
nice
<Sarayan>
I wonder how similar it is to the casio stuff
<Lord_Nightmare>
if you want detailed info on how the opcodes etc work you will need to ask sergm, i didn't get full notes from him on how it works
<Lord_Nightmare>
IIRC like on the la32, the internal multiplier in the boss reverb chip cheats for the low order bits
<andlabs>
ROMs are listed in MAME so
<andlabs>
I think the actual synth chips are the same
<andlabs>
it's the computer parts that are different
<andlabs>
same with the DX11 and TX81Z
<andlabs>
which is annoying because they have to be separate files in MAME as a result
<Sarayan>
andlabs: they don't have to
<andlabs>
oh? all right then, though they still wouldn't be able to share mcuh
<andlabs>
other than the sound code which is separate
<andlabs>
espeicially since one is a keyboard and the other is a rack module
<Sarayan>
now that would be a reason to keep them separate
<Sarayan>
if they don't share much at all there's no real reason to keep them together