Supplementary Material - Roland FP-7F Implementation Manual

4. Supplementary material

●Decimal and Hexadecimal table
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.
Dec. Hex. Dec. Hex.
0 00H 32 20H
1 01H 33 21H
22H
2 02H 34
3 03H 35 23H
4 04H 36 24H
5 05H 37 25H
6 06H 38 26H
7 07H 39 27H
8 08H 40 28H
09H 41 29H
9
10 0AH 42 2AH
11 0BH 43 2BH
12 0CH 44 2CH
13 0DH 45 2DH
14 0EH 46 2EH
15 0FH 47 2FH
10H 48 30H
16
31H
17 11H 49
18 12H 50 32H
19 13H 51 33H
20 14H 52 34H
21 15H 53 35H
22 16H 54 36H
23 17H 55 37H
18H 56 38H
24
25 19H 57 39H
26 1AH 58 3AH
27 1BH 59 3BH
28 1CH 60 3CH
29 1DH 61 3DH
30 1EH 62 3EH
1FH 63 3FH
31
* Decimal values such as MIDI channel, bank select, and program change are
listed as one (1) 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 "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.
<Example1> What is the decimal expression of 5AH?
From the preceding table, 5AH = 90
<Example2> 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
<Example3> 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
<Example4> What is the nibbled expression of the decimal value 1258?
16) 1258
16) 78... 10
Dec. Hex. Dec Hex.
64 40H 96 60H
65 41H 97 61H
66 42H 98
62H
67 43H 99
63H
68 44H 100 64H
69 45H 101 65H
70 46H 102 66H
71 47H 103 67H
72 48H 104 68H
73 49H 105 69H
74 4AH 106
6AH
107
75 4BH 6BH
76 4CH 108 6CH
77 4DH 109 6DH
78 4EH 110 6EH
79 4FH 111 6FH
80 50H 70H
112
81 51H
113 71H
82 52H
114 72H
83 53H 115 73H
84 54H 116 74H
85 55H 117 75H
86 56H 118 76H
87 57H 77H
119
88 58H
120 78H
89 59H
121 79H
90 5AH 122 7AH
91 5BH 123 7BH
92 5CH 124 7CH
93 5DH 125 7DH
94 5EH 126 7EH
95 5FH 7FH
127
4... 14
16)
0... 4
Since from the preceding table, 0 = 00H, 4 = 04H, 14 = 0EH, 10 = 0AH, the
answer is 00 04 0E 0AH.
●Examples of actual MIDI messages
<Example1> 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.
<Example2> 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).
<Example3> 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 128 + 0 = 8192) is 0, so
this Pitch Bend Value is 28 00H - 40 00H = 40 x 128 + 0 - (64 x 128 + 0) = 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.
<Example4> 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 sources 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 source 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
16