3-digit numbers for message type and channel?
I guess that would be decimal representations of raw midi bytes.
From this website:
http://www.ccarh.org/courses/253/lab/cinmidi/
0×80 Note-off
0×90 Note-on
0xA0 Aftertouch
0xB0 Continuous Controller
0xC0 Patch Change
0xD0 Channel Pressure
0xE0 Pitch Wheel
0xF0 System Messages
Since hex goes from 0-15 per digit is convenient for midi :)
0×90 note on, channel one
0×91 note on, channel two
…
0×99 note on, channel ten
0x9A note on, channel eleven
…
0x9F note on, channel sixteen
that is the other way around of course…
somewhere in the late 70s early 80s some thought:
"since we will be using hex.. this new "midi" protocol will have 16 channels" :)
btw, these messages (note on/off etc) would be the status bytes, describing how the following data should be interpreted. after that comes one or more data bytes.
so, first comes a status byte 0×92. this tells the device that the following data bytes should be interpreted as a note on on channel 3.
then come two data bytes, first the note number and then the velocity. the synth will play on channel 3 this note number with this velocity.