Yamaha's own MIDI definition

[The Old Crow]

On Thu, 24 Aug 2000, Dan Gendreau wrote:

> Yeah, My Original DX-7 does the same damn thing. Unless you can find someone
> who likes reverse-compiling 8-bit assembler language, you are out of luck. I
> for one dont.

  I've done some partial-hacking of the DX7 ROM, mainly to put 'Property
of Scott Rider' on the display on power-on, but I also looked at the MIDI
routines just to see what was going on.  The problem I encountered was
that the code to calculate key velocity from the travel time between
switches wasn't in the main OS ROM, but was in the slave CPU's on-chip
mask ROM.  The best one can do is map the 100 velocity values to 127
values with some missing codes.

  The only person I know that has really hacked into Yamaha keyboard code
hard is Steve Glennie-Smith of the DX7 mailling list.  He might have some
additional insight into key velocity mapping of various Yamaha boards.

> If I were going to do it however, I would use a little 8-pin AVR
> microcontroller to translate the velocity. You should be able to do it
> with no other components. Then I would mount it inside my keyboard,
> cut the traces going to the existing midi-out jack and wire in the
> Atmel chip in seres.

  Yeah, this would work too, although it would have to have enough smarts
to observe running status on note on/off (again, not too tough).

  Do Amtel parts have on-chip osc. and whatnot similar to 8-pin PICs?

Crow

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