are expressed as hexadecimal values for each 7 bits. The following table shows how these correspond to decimal numbers. I H I H I üüH Ü1H ü2H ü3H ü4H ü5H ü6H ü7H ü8H ü9H üAH üBH üCH üDH üEH üFH 1ÜH 11H 12H 13H 14H 15H 16H 17H 18H 19H 1AH 1BH 1CH 1DH 1EH 1FH 2üH 21H 22H 23H 2 4H 25H 26H 27H 28H 29H 2AH 2BH 2CH 2DH 2EH 2FH 3üH 31H 32H 33H 3 4H 35H 36H 37H 38H 39H 3AH 3BH 3CH 3DH 3EH 3FH 64 65 66 67 68 69 7ü 71 72 73 74 75 76 77 78 79 8ü 81 82 83 84 85 86 87 88 89 9ü 91 92 93 94 95 4üH 41H 42H 43H 44H 45H 46H 47H 48H 49H 4AH 4BH 4CH 4DH 4EH 4FH 5üH 51H 52H 53H 54H 55H 56H 57H 58H 59H 5AH 5BH 5CH 5DH 5EH 5FH 1üü 1Ü1 1ü2 1ü3 1ü4 1ü5 1ü6 1ü7 1ü8 1ü9 11ü 111 112 113 114 115 116 117 118 119 12ü 121 122 123 124 125 126 127 6üH 61H 62H 63H 6 4H 65H 66H 67H 68H 69H 6AH 6BH 6CH 6DH 6EH 6FH 7üH 71H 72H 73H 7 4H 75H 76H 77H 78H 79H 7AH 7BH 7CH 7DH 7EH 7FH D: decimal H: hexadecimal * Decimal values such as MIDI channel 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. What is the decimal expression of 5AH? From the preceding table, 5AH = 90 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 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 What is the nibbled expression of the decimal value 1258? 16 ) 1258 16 )_78 ...10 16 )_4 ...14 0 ... 4 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 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. 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). 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. 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 OO MIDI ch.4, lower byte of RPN parameter number: OOH (B3) 65 OO (MIDI ch.4) upper byte of RPN parameter number: OOH (B3) O6 OC (MIDI ch.4) upper byte of parameter value: OCH (B3) 26 OO (MIDI ch.4) lower byte of parameter value: OOH (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 R...
)
