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MIDI Implementation
3. Supplementary Material
ÁDecimal and Hexadecimal Table
(Hexadecimal Numbers are Indicated by "H")
In MIDI documentation, data values and addresses/sizes of exclusive messages etc.
are expressed as hexadecimal values for each 7 bits.
The following table shows how these correspond to decimal numbers.
D
H
D
H
D
0
0 0 H
32
2 0 H
64
1
0 1 H
33
2 1 H
65
2
0 2 H
34
2 2 H
66
3
0 3 H
35
2 3 H
67
4
0 4 H
36
2 4 H
68
5
0 5 H
37
2 5 H
69
6
0 6 H
38
2 6 H
70
7
0 7 H
39
2 7 H
71
8
0 8 H
40
2 8 H
72
9
0 9 H
41
2 9 H
73
10
0 A H
42
2 A H
74
11
0 B H
43
2 B H
75
12
0 C H
44
2 C H
76
13
0DH
45
2DH
77
14
0 E H
46
2 E H
78
15
0 F H
47
2 F H
79
16
1 0 H
48
3 0 H
80
17
1 1 H
49
3 1 H
81
18
1 2 H
50
3 2 H
82
19
1 3 H
51
3 3 H
83
20
1 4 H
52
3 4 H
84
21
1 5 H
53
3 5 H
85
22
1 6 H
54
3 6 H
86
23
1 7 H
55
3 7 H
87
24
1 8 H
56
3 8 H
88
25
1 9 H
57
3 9 H
89
26
1 A H
58
3 A H
90
27
1 B H
59
3 B H
91
28
1 C H
60
3 C H
92
29
1DH
61
3DH
93
30
1 E H
62
3 E H
94
31
1 F H
63
3 F H
95
D: decimal
H: hexadecimal
* Decimal expressions used for MIDI channel, bank select, and program change are 1
greater than the decimal value shown in the above table.
* Hexadecimal values in 7-bit units can express a maximum of 128 levels in one byte
of data. If the data requires greater resolution, two or more bytes are used. For
example, a value indicated by a hexadecimal expression in two 7-bit bytes aa bbH
would be aa x 128 + bb.
* Data marked "nibbled" is expressed in hexadecimal in 4-bit units. A value expressed
as a 2-byte nibble 0a 0bH has the value of a x 16 + b.
<Example 1>
What is the decimal expression of 5AH?
From the preceding table, 5AH = 90
<Example 2>
What is the decimal expression of the value 12 34H given as hexadecimal for each 7
bits?
From the preceding table, since 12H = 18 and 34H = 52
18 x 128 + 52 = 2356
18
H
D
H
4 0 H
96
6 0 H
4 1 H
97
6 1 H
4 2 H
98
6 2 H
4 3 H
99
6 3 H
4 4 H
100
6 4 H
4 5 H
101
6 5 H
4 6 H
102
6 6 H
4 7 H
103
6 7 H
4 8 H
104
6 8 H
4 9 H
105
6 9 H
4 A H
106
6 A H
4 B H
107
6 B H
4 C H
108
6 C H
4DH
109
6DH
4 E H
110
6 E H
4 F H
111
6 F H
5 0 H
112
7 0 H
5 1 H
113
7 1 H
5 2 H
114
7 2 H
5 3 H
115
7 3 H
5 4 H
116
7 4 H
5 5 H
117
7 5 H
5 6 H
118
7 6 H
5 7 H
119
7 7 H
5 8 H
120
7 8 H
5 9 H
121
7 9 H
5 A H
122
7 A H
5 B H
123
7 B H
5 C H
124
7 C H
5DH
125
7DH
5 E H
126
7 E H
5 F H
127
7 F H
ÁExample of an Exclusive Message and Calculating a Checksum
Roland Exclusive messages are transmitted with a checksum at the end (before F7)
to make sure that the message was correctly received. The value of the checksum is
determined by the address and data (or size) of the transmitted exclusive message.
À How to Calculate the Checksum
(Hexadecimal Numbers are Indicated by "H")
The checksum is a value that produces a lower 7 bits of zero when the address, size,
and checksum itself are summed. If the exclusive message to be transmitted has an
address of aa bb ccH and the data is dd ee ffH, the actual calculation would be as
follows:
aa + bb + cc + dd + ee + ff = sum
sum / 128 = quotient ... remainder
128 - remainder = checksum
(However, the checksum will be 0 if the remainder is 0.)
<Example>
When setting PGM Select to INPUT 2 for data set 1
From the "Parameter Address Map, " the address of the PGM Select is 00H 21H 00H and
the INPUT 2 parameter is 01H. Therefore ...
F0H 41H 10H
00H 00H 00H 00H 02H
(1)
(2)
(3)
(4)
(1) Exclusive Status
(2) ID Number (Roland)
(3) Device ID
(4) Model ID
(5) Command ID (DT1)
(6) Address
(7) Data
(8) Checksum
(9) EOX
Next calculate the checksum. Add (6) to (7).
00H + 21H + 00H + 01H = 0 + 33 + 0 + 1 = 34 (sum)
34 (sum) / 128 = 0 (quotient) ... 34 (remainder)
Checksum = 128 - 34 (remainder) = 94 = 5EH
Thus, the message to transmit is :
F0H 41H 10H 00H 00H 00H 00H 02H 12H 00H 21H 00H 01H 5EH F7H
12H 00H 21H 00H
01H ??H F7H
(5)
(6)
(7)
(8)
(9)
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