Alesis D4 Service Manual page 28

The seventh byte "qq" is the opcode. If bit 6 of this opcode is set the message is a data
request and the opcode is always followed immediately by an end-of-exclusive status byte.
Opcodes with bit 6 cleared are data dump headers that identify the type of data that is to follow.
In either case, the lower six bits of the opcode represent the same data structure, whether the
message is a data request or a data dump.
Most system exclusive messages on the D4 include a checksum byte after the data
immediately before the F7H end-of-exclusive status byte. This checksum is the modulo 128
addition of all the data bytes contained in the message starting with the byte immediately
following the opcode.
Opcode
0000 0000
0000 0001
0000 0010
0000 0011
0000 0100
0000 0101
0000 0110
---- ----
---- ----
0001 1111
001p pppp
0011 0101
---- ----
---- ----
0011 1111
01qq qqqq
When a "SYSTEM (ALL)" bulk dump is initiated from the front panel the D4's entire
memory contents get transmitted out MIDI in a series of 25 system exclusive messages. This
series begins with the Program Change Table message, and is followed by the Trigger Setup
message, the Edit Buffer message, 21 consecutive Single Set messages (beginning with
Drumset 0), and finally the System Info message.
Note that it is possible in some systems to overflow the D4's midi receive buffer when
sending data for more than one drumset. If this happens the transmitting device should pause
for at least 250 milliseconds every 256 bytes to insure that the receiving D4 has enough time to
manage drumset memory.
Message 0 / System Info
Data Format (following header):
Byte
7
8
9
10
11
Alesis D4/D5 Drum Modules Service Manual
Description
System Info
Drumset Data for Edit Buffer
Old Trigger Setup (version 1.01 only) 33
Program Change Table
Display Message
New Trigger Setu
Reserved / Unused
---
---
Reserved / Unused
Drumset Data for Drumset 0-20
Reserved / Unused
---
---
Reserved / Unused
Requests for opcodes 0-63
Bit Field
0000 0000 Opcode = System Info
0bbb bbbb System Byte (see specific bit definitions following)
0000 nnnn Midi Channel (0-15)
000s ssss Currently selected drumset (0-20)
1111 0111 EOX
Length
(Total bytes)
11
343
137
40
69
x
x
x
x
343
x
x
x
x
8
Description
24
Checksum
No
Yes
Yes
Yes
No
Yes
x
x
x
x
Yes
x
x
x
x
No
02/19/03