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13. How is the data within a Sysex Message formatted, and why do
I see extra Bytes of “0x00” sprinkled around (every 8th Byte)?
A common SYSEX packet follows the following scheme in a Karma :
0xF0 - Start of Exclusive Data
0x42 - Korg ID
0x3G - Karma Music Workstation ID
0x5D - Karma Music Workstation Member Code
0x?? - Function ID
....
.... - Data (encoded as described below)
....
0xF7 - End of Exclusive
Due to the fact that Data Bytes must have the 8th bit as “0” (see the
preceding question), data values range from 0x00 to 0x7F. So a special
byte is used every 7 bytes to encode the 8th bit of the previous 7 bytes in
it. So you have to decode this byte to know the full values of the 7
previous bytes.
In other words, 7 bytes of 8 bits are converted into 7 values of 7 bits (the
bits 0 to 6 of each byte), and an extra byte containing the most
significant bit of each of the 7 bytes is also transmitted (first).
Example : the seven bytes :
A7-A6-A5-A4-A3-A2-A1-A0
B7-B6-B5-B4-B3-B2-B1-B0
C7-C6-C5-C4-C3-C2-C1-C0
D7-D6-D5-D4-D3-D2-D1-D0
E7-E6-E5-E4-E3-E2-E1-E0
F7-F6-F5-F4-F3-F2-F1-F0
G7-G6-G5-G4-G3-G2-G1-G0
are sent as 8 bytes :
00-A7-B7-C7-D7-E7-F7-G7
00-A6-A5-A4-A3-A2-A1-A0
00-B6-B5-B4-B3-B2-B1-B0
00-C6-C5-C4-C3-C2-C1-C0
00-D6-D5-D4-D3-D2-D1-D0
00-E6-E5-E4-E3-E2-E1-E0
00-F6-F5-F4-F3-F2-F1-F0
00-G6-G5-G4-G3-G2-G1-G0
At the end of the SYSEX data you may not have all the 7 bytes (if
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