OPQ Programmer’s Guide V 1.1
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5.3 Register addresses 20H...3FH
Register group 1 contains operator frequency settings. All settings are operator pair
specific. The addessing scheme is described in chapter 4.3.
5.3.1 Registers 20H...2FH: Octave / frequency hi-nibble
D7
D6
D5
D4
D3
D2
D1
D0
-
OCT2
OCT1
OCT0
FRQ11
FRQ10
FRQ9
FRQ8
OCT2...OCT0
Octave number 0...7.
FRQ11...FRQ8
4 most significant bits of the 12-bit frequency number.
5.3.2 Registers 30H...3FH: Frequency lo-byte
D7
D6
D5
D4
D3
D2
D1
D0
FRQ7
FRQ6
FRQ5
FRQ4
FRQ3
FRQ2
FRQ1
FRQ0
FRQ7...FRQ0
8 least significant bits of the 12-bit frequency number.
Octave and frequency number together define the operator’s nominal frequency. The
actual output frequency is still affected by detune and multiplier defined in registers
40H...5FH.
5.3.3 Octave and frequency numbering
Octaves are numbered so that the octave containing middle C (261.6 Hz) as the lowest
note is octave number 4.
The 12-bit frequency number spans for one octave. Numbers used in PSR-70 firmware
are:
Note
Freq number
C
4CAH
C#
513H
D
560H
D#
5B2H
E
609H
F
665H