Supplementary Material - Roland VR-120HD Manual

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 00H 32 20H 64
1 01H 33 21H 65
2 02H 34 22H 66
3 03H 35 23H 67
4 04H 36 24H 68
5 05H 37 25H 69
6 06H 38 26H 70
7 07H 39 27H 71
8 08H 40 28H 72
9 09H 41 29H 73
10 0AH 42 2AH 74
11 0BH 43 2BH 75
12 0CH 44 2CH 76
13 0DH 45 2DH 77
14 0EH 46 2EH 78
15 0FH 47 2FH 79
16 10H 48 30H 80
17 11H 49 31H 81
18 12H 50 32H 82
19 13H 51 33H 83
20 14H 52 34H 84
21 15H 53 35H 85
22 16H 54 36H 86
23 17H 55 37H 87
24 18H 56 38H 88
25 19H 57 39H 89
26 1AH 58 3AH 90
27 1BH 59 3BH 91
28 1CH 60 3CH 92
29 1DH 61 3DH 93
30 1EH 62 3EH 94
31 1FH 63 3FH 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
H D H
40H 96 60H
41H 97 61H
42H 98 62H
43H 99 63H
44H 100 64H
45H 101 65H
46H 102 66H
47H 103 67H
48H 104 68H
49H 105 69H
4AH 106 6AH
4BH 107 6BH
4CH 108 6CH
4DH 109 6DH
4EH 110 6EH
4FH 111 6FH
50H 112 70H
51H 113 71H
52H 114 72H
53H 115 73H
54H 116 74H
55H 117 75H
56H 118 76H
57H 119 77H
58H 120 78H
59H 121 79H
5AH 122 7AH
5BH 123 7BH
5CH 124 7CH
5DH 125 7DH
5EH 126 7EH
5FH 127 7FH
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 1BH 00H and
the INPUT 2 parameter is 01H. Therefore ...
F0H 41H 10H 00H 00H 00H 00H 25H
(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 25H 12H 00H 1BH 00H 1EH 47H F7H
39
MIDI Implementation
12H 00H 1BH 00H 1EH ??H F7H
(5) (6) (7) (8) (9)