Register Addresses 20H; Registers 20H; Registers 30H; Octave And Frequency Numbering - Yamaha YM3806 Programmer's Manual

OPQ Programmer's Guide V 1.1
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
- OCT2
OCT2...OCT0
FRQ11...FRQ8
5.3.2 Registers 30H...3FH: Frequency lo-byte
D7 D6
FRQ7 FRQ6
FRQ7...FRQ0
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:
D5 D4
OCT1 OCT0
Octave number 0...7.
4 most significant bits of the 12-bit frequency number.
D5 D4
FRQ5 FRQ4
8 least significant bits of the 12-bit frequency number.
Note
C
C#
D
D#
E
F
D3 D2
FRQ11 FRQ10
D3 D2
FRQ3 FRQ2
Freq number
4CAH
513H
560H
5B2H
609H
665H
D1 D0
FRQ9 FRQ8
D1 D0
FRQ1 FRQ0
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