MT-32 SysEx query

[Alistair]

Hey folks,

I'm editing some Sierra MIDI files, and I noticed two reverb changes in one MIDI- a SFX plays for a very short time, and has a SysEx sent at the start of it, and when it changes over to the music, another SysEx is sent.

Number 1 is:
f0 41 10 16 12 10 00 01 00 05 06 64 f7

Number 2 is:
f0 41 10 16 12 10 00 01 00 03 03 69 f7

My question is, what does this mean? I know the first 5-6 binaries are standard and F7 is 'end of sysex', but I was wondering what the rest is.

Some guesses were:
Is 64 and 69 the checksums?
And is 00 01 00 changing the reverb setting to room?

Anyway, I was obviously most curious about the 05 06 64 and 03 03 69.

But anything would be helpful. Thanks in advance, guys/gals.
- Alistair

[Zemus]

Well, 10 00 01 is the memory address the first following byte is written to. What follows are 3 bytes (which are then written to addresses 10 00 01, 10 00 02, and 10 00 03). 64 and 69 are just checksums.

Address 10 00 01 is REVERB MODE. That's set to 0 in both, which is "room". 10 00 02 is REVERB TIME and 10 00 03 REVERB LEVEL. Not sure what they do. Maybe they set the length and volume of the reverb effect. Anyways, they're the ones that are being changed.

[NewRisingSUn]

f0 41 10 16 12 10 00 01 00 05 06 64 f7

Reverb mode=Room,time=5,level=6. The default reverb is 0 5 3, meaning the reverb will only sound louder than normal. 64 is the checksum, as stated.

f0 41 10 16 12 10 00 01 00 03 03 69 f7

Room, time=3, level=3. This reduces the reverb. It will be as loud as the default, but shorter.