Nintendo DMG-01 - Game Boy Console Manual page 46

2.13.1. I/O Registers
20. FF1C (NR 32)
Name
Contents - Sound Mode 3 register, Select output
* - Wave Pattern RAM is located from $FF30-$FF3f.
21. FF1D (NR 33)
Name
Contents - Sound Mode 3 register, frequency's
22. FF1E (NR 34)
Name
Contents - Sound Mode 3 register, frequency's
Page 46
- NR 32
level (R/W)
Only bits 6-5 can be read
Bit 6-5 - Select output level
- NR 33
lower data (W)
Lower 8 bits of an 11 bit frequency (x).
- NR 34
higher data (R/W)
Only bit 6 can be read.
00: Mute
01: Produce Wave Pattern RAM
Data as it is(4 bit length)
10: Produce Wave Pattern RAM
data shifted once to the
RIGHT (1/2)
11: Produce Wave Pattern RAM
data shifted twice to the
RIGHT (1/4)
TM
Game Boy CPU Manual
(4 bit length)
(4 bit length)
V 1.01