Roland XP-80 Owner's Manual download pdf (Page 225)

* Decimal expressions such as used for MIDI channel, Bank Select, and

Program Change will be the value 1 greater than the decimal value given in

the above table.

* Since each MIDI byte carries 7 significant data bits, each byte can express

a maximum of 128 different values. Data for which higher resolution is

required must be transmitted using two or more bytes. For example a value

indicated as a two-byte value of aa bbH would have a value of aa x 128 +

bb.

* For a signed number (+/-), 00H = -64, 40H = +/-0, and 7FH = +63. I.e., the

decimal equivalent will be 64 less than the decimal value given in the above

table. For a two-byte signed number, 00 00H = -8192, 40 00H = +/-0, and

7F 7FH = +8191. For example the decimal expression of aa bbH would be

aa bbH - 40 00H = (aa x 128 + bb - 64 x 128.

* Hexadecimal notation in two 4-bit units is used for data indicated as “nib-

bled”. The nibbled two-byte value of 0a 0b H would be a x 16 + b.

<Example 1> What is the decimal equivalent of 5AH?

From the above table, 5AH = 90.

<Example 2> What is the decimal equivalent of the 7-bit hexa-

decimal values 12 34H?

From the above table, 12H = 18 and 34H = 52

Thus, 18 x 128 + 52 = 2356

<Example 3> What is the decimal equivalent of the nibbled

expression 0A 03 09 0DH?

From the above table, 0AH = 10, 03H = 3, 09H = 9, 0DH = 13

Thus, the result is ((10 x 16 + 3) x 16 + 9) x 16 + 13 = 41885

<Example 4> What is the nibbled equivalent of the decimal

number 1258?

16 ) 1258

16 ) 78 ...10

16 ) 4 ...14

0 ... 4

From the above table, 0=00H, 4=04H, 14=0EH, 10=0AH

Thus 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 of MIDI CH = 3, note num-

ber 62 (note name 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 of MIDI CH = 15,

Program number 74 (in the GS sound map, Flute).

<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 of the Pitch Bend value, and the 3rd byte

(28H=40) is the MSB. However since the Pitch Bend is a signed number with 0

at 40 00H ( = 64 x 128 + 0 = 8192), the Pitch Bend value in this case is

28 00H - 40 00H = 40 x 128 + 0 - (64 x 128 + 0) = 5120 - 8192 = -3072

If we assume that the Pitch Bend Sensitivity is set to two semitones, the pitch

will change only -200 cents for a Pitch Bend value of -8192 (00 00H). Thus, this

message is specifying a Pitch Bend of -200 x (-3072) ÷ (-8192) = -75 cents on

MIDI CH = 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. In

Control Change messages, the 2nd byte is the controller number, and the 3rd

byte is the parameter value. MIDI allows what is known as “running status,”

when if messages of the the same status follow each other, it is permitted to

omit the second and following status bytes. In the message above, running

status is being used, meaning that the message has the following content.

B3 64 00 MIDI CH = 4, RPN parameter number LSB : 00H

(B3) 65 00 MIDI CH = 4, RPN parameter number MSB : 00H

(B3) 06 0C MIDI CH = 4, parameter value MSB : 0CH

(B3) 26 00 MIDI CH = 4, parameter value LSB : 00H

(B3) 64 7F MIDI CH = 4, RPN parameter number LSB : 7FH

(B3) 65 7F MIDI CH = 4, RPN parameter number MSB : 7FH

Thus, this message transmits a parameter value of 0C 00H to RPN parameter

number 00 00H on MIDI CH = 4, and then sets the RPN parameter number to

7F 7FH.

The function assigned to RPN parameter number 00 00H is Pitch Bend

Sensitivity, and the MSB of the parameter value indicates semitone steps.

Since the MSB of this parameter value is 0CH = 12, the maximum width of

pitch bend is being set to ±12 semitones (1 octave) (GS sound sources ignore

the LSB of Pitch Bend Sensitivity, but it is best to transmit the LSB (parameter

value 0) as well, so that the message can be correctly received by any device.

Once the parameter number has been set for RPN or NRPN, all subsequent

Data Entry messages on that channel will be effective. Thus, it is recommend-

ed that after you have made the change you want, you set the parameter num-

ber to 7F 7FH (an “unset” or “null” setting). The final (B3) 64 7F (B3) 65 7F is

for this purpose.

It is not a good idea to store many events within the data of a song (e.g., a

Standard MIDI File song) using running status as shown in <Example 4>.

When the song is paused, fast-forwarded or rewound, the sequencer may not

be able to transmit the proper status, causing the sound source to misinterpret

the data. It is best to attach the proper status byte to all events.

It is also important to transmit RPN or NRPN parameter number settings and

parameter values in the correct order. In some sequencers, data events record-

ed in the same clock (or a nearby clock) can sometimes be transmitted in an

order other than the order in which they were recorded. It is best to record

such events at an appropriate interval (1 tick at TPQN=96, or 5 ticks at

TPQN=480).

* TPQN : Ticks Per Quarter Note (i.e., the time resolution of the sequencer)

● Examples of exclusive messages and calculating the check-

sum

Roland exclusive messages (RQ1, DT1) are transmitted with a checksum at the

end of the data (before F7) to check that the data was received correctly. The

value of the checksum is determined by the address and data (or size) of the

exclusive message.

❍ How to calculate the checksum (hexadecimal values are indi-

cated by a ‘H’)

The checksum consists of a value whose lower 7 bits are 0 when the address,

size and checksum itself are added.

The following formula shows how to calculate the checksum when the exclu-

sive message to be transmitted has an address of aa bb cc ddH, and data or

size of ee ffH.

aa + bb + cc + dd + ee + ff = total

total ÷ 128 = quotient ... remainder

128 - remainder = checksum

<Example 1> Setting the Performance Common REVERB TYPE

to DELAY (DT1).

The “Parameter address map” indicates that the starting address of the

Temporary Performance is 01 00 00 00H, that the Performance Common offset

address is 00 00H, and that the REVERB TYPE address is 00 28H. Thus, the

address is:

01 00 00 00H

00 00H

+) 00 28H

01 00 00 28H

Since DELAY is parameter value 06H,

F0 41 10 6A 12 01 00 00 28 06 ?? F7

(1) (2) (3) (4) (5) address data checksum (6)

(1) Exclusive status (2) ID number (Roland) (3) device ID(17)

(4) model ID (XP-80) (5) command ID (DT1) (6) EOX

Next we calculate the checksum.

01H + 00H + 00H + 28H + 06H = 1 + 0 + 0 + 40 + 6 = 47 (sum)

47 (total) ÷ 128 = 0 (quotient) ... 47 (remainder)

checksum = 128 - 47 (quotient) = 81 = 51H

This means that the message transmitted will be F0 41 10 6A 12 01 00 00 28 06

51 F7.

<Example 2> Retrieving data for USER:03 Performance Part 3

(RQ1)

The “Parameter address map” indicates that the starting address of USER:03

is 10 02 00 00H, and that the offset address of Performance Part 3 is 12 00H.

Thus, the address is:

10 02 00 00H

+) 12 00H

10 02 12 00H

227

Chapter 12. Supplementary material

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Roland XP-80 Owner's Manual Page 225

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