Roland EDIROL UM-880 Manual page 55

5. Supplementary material
Decimal and Hexadecimal table
(An "H" is appended to the end of numbers in hexadecimal notation.)
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.
fig.11-22e
Dec. Hex. Dec.
0 00H 32
1 01H 33
2 02H 34
3 03H 35
4 04H 36
5 05H 37
6 06H 38
7 07H 39
8 08H 40
9 09H 41
10 0AH 42
11 0BH 43
12 0CH 44 2CH
13 0DH 45 2DH
14 0EH 46
15 0FH 47
16 10H 48
17 11H 49
18 12H 50
19 13H 51
20 14H 52
21 15H 53
22 16H 54
23 17H 55
24 18H 56
25 19H 57
26 1AH 58
27 1BH 59
28 1CH 60 3CH
29 1DH 61 3DH
30 1EH 62
31 1FH 63
* Decimal values such as MIDI channel, bank select, and program change are
listed as one greater than the values given in the above table.
* A 7-bit byte can express data in the range of 128 steps. For data where greater
precision is required, we must use two or more bytes. For example, two
hexadecimal numbers aa bbH expressing two 7-bit bytes would indicate a value
of aa x 128+bb.
* In the case of values which have a +/- sign, 00H = -64, 40H = +/-0, and 7FH =
+63, so that the decimal expression would be 64 less than the value given in the
above chart. In the case of two types, 00 00H = -8192, 40 00H = +/-0, and 7F 7FH
= +8191. For example, if aa bbH were expressed as decimal, this would be aa
bbH - 40 00H = aa x 128+bb - 64 x 128.
* Data marked "Use nibbled data" 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
<Example 3> What is the decimal expression of the nibbled value 0A 03 09 0D ?
From the preceding table, since 0AH = 10, 03H = 3, 09H = 9, 0DH = 13
((10 x 16+3) x 16+9) x 16+13 = 41885
<Example 4> What is the nibbled expression of the decimal value 1258?
16) 1258
16) 78 ... 10
16) 4 ... 14
0 ... 4
Hex. Dec. Hex. Dec. Hex.
20H 64 40H 96 60H
21H 65 41H 97 61H
22H 66 42H 98 62H
23H 67 43H 99 63H
24H 68 44H 100 64H
25H 69 45H 101 65H
26H 70 46H 102 66H
27H 71 47H 103 67H
28H 72 48H 104 68H
29H 73 49H 105 69H
2AH 74 4AH 106 6AH
2BH 75 4BH 107 6BH
76 4CH 108 6CH
77 4DH 109 6DH
2EH 78 4EH 110 6EH
2FH 79 4FH 111 6FH
30H 80 50H 112 70H
31H 81 51H 113 71H
32H 82 52H 114 72H
33H 83 53H 115 73H
34H 84 54H 116 74H
35H 85 55H 117 75H
36H 86 56H 118 76H
37H 87 57H 119 77H
38H 88 58H 120 78H
39H 89 59H 121 79H
3AH 90 5AH 122 7AH
3BH 91 5BH 123 7BH
92 5CH 124 7CH
93 5DH 125 7DH
3EH 94 5EH 126 7EH
3FH 95 5FH 127 7FH
Since from the preceding table, 0 = 00H, 4 = 04H, 14 = 0EH, 10 = 0AH, the result is:
00 04 0E 0AH.
Examples of actual MIDI messages
<Example 1> 92 3E 5F
9n is the Note-on status, and n is the MIDI channel number. Since 2H = 2, 3EH = 62,
and 5FH = 95, this is a Note-on message with MIDI CH = 3, note number 62 (note
name is D4), and velocity 95.
<Example 2> CE 49
CnH is the Program Change status, and n is the MIDI channel number. Since EH =
14 and 49H = 73, this is a Program Change message with MIDI CH = 15, program
number 74 (Flute in GS).
<Example 3> EA 00 28
EnH is the Pitch Bend Change status, and n is the MIDI channel number. The 2nd
byte (00H = 0) is the LSB and the 3rd byte (28H = 40) is the MSB, but Pitch Bend
Value is a signed number in which 40 00H (= 64 x 12+80 = 8192) is 0, so this Pitch
Bend Value is
28 00H - 40 00H = 40 x 12+80 - (64 x 12+80) = 5120 - 8192 = -3072
If the Pitch Bend Sensitivity is set to 2 semitones, -8192 (00 00H) will cause the pitch
to change -200 cents, so in this case -200 x (-3072) ÷ (-8192) = -75 cents of Pitch Bend
is being applied to MIDI channel 11.
<Example 4> B3 64 00 65 00 06 0C 26 00 64 7F 65 7F
BnH is the Control Change status, and n is the MIDI channel number. For Control
Changes, the 2nd byte is the control number, and the 3rd byte is the value. In a case
in which two or more messages consecutive messages have the same status, MIDI
has a provision called "running status" which allows the status byte of the second
and following messages to be omitted. Thus, the above messages have the
following meaning.
B3 64 00 MIDI ch.4, lower byte of RPN parameter number:00H
(B3) 65 00 (MIDI ch.4) upper byte of RPN parameter number:00H
(B3) 06 0C (MIDI ch.4) upper byte of parameter value:0CH
(B3) 26 00 (MIDI ch.4) lower byte of parameter value:00H
(B3) 64 7F (MIDI ch.4) lower byte of RPN parameter number:7FH
(B3) 65 7F (MIDI ch.4) upper byte of RPN parameter number:7FH
In other words, the above messages specify a value of 0C 00H for RPN parameter
number 00 00H on MIDI channel 4, and then set the RPN parameter number to 7F
7FH.
RPN parameter number 00 00H is Pitch Bend Sensitivity, and the MSB of the value
indicates semitone units, so a value of 0CH = 12 sets the maximum pitch bend
range to +/-12 semitones (1 octave). (On GS sound generators the LSB of Pitch
Bend Sensitivity is ignored, but the LSB should be transmitted anyway (with a
value of 0) so that operation will be correct on any device.)
Once the parameter number has been specified for RPN or NRPN, all Data Entry
messages transmitted on that same channel will be valid, so after the desired value
has been transmitted, it is a good idea to set the parameter number to 7F 7FH to
prevent accidents. This is the reason for the (B3) 64 7F (B3) 65 7F at the end.
It is not desirable for performance data (such as Standard MIDI File data) to contain
many events with running status as given in <Example 4>. This is because if
playback is halted during the song and then rewound or fast-forwarded, the
sequencer may not be able to transmit the correct status, and the sound generator
will then misinterpret the data. Take care to give each event its own status.
It is also necessary that the RPN or NRPN parameter number setting and the value
setting be done in the proper order. On some sequencers, events occurring in the
same (or consecutive) clock may be transmitted in an order different than the order
in which they were received. For this reason it is a good idea to slightly skew the
time of each event (about 1 tick for TPQN = 96, and about 5 ticks for TPQN = 480).
* TPQN: Ticks Per Quarter Note
MIDI Implimentation
55