Nintendo NES-001 - Entertainment System Game Console Documentation page 35

$2006 Write
$2007 Read / Write
$4000 Write
$4001 Write
$4002 Write
$4003 Write
$4004 Write
$4005 Write
$4006 Write
$4007 Write
$4008 Write
$4009 Write
$400A Write
$400B Write
$400C Write
$400E Write
$400F Write
$4010 Write
$4011 Write
$4012 Write
$4013 Write
$4014 Write
$4015 Read / Write
$4016 Read / Write
$4017 Read / Write
VRAM Address Register 2.
VRAM I/O Register:
Reads or writes a byte from VRAM at the current address.
pAPU Pulse 1 Control Register.
pAPU Pulse 1 Ramp Control Register.
pAPU Pulse 1 Fine Tune (FT) Register.
pAPU Pulse 1 Coarse Tune (CT) Register.
pAPU Pulse 2 Control Register.
pAPU Pulse 2 Ramp Control Register.
pAPU Pulse 2 Fine Tune Register.
pAPU Pulse 2 Coarse Tune Register.
pAPU Triangle Control Register 1.
pAPU Triangle Control Register 2.
pAPU Triangle Frequency Register 1.
pAPU Triangle Frequency Register 2.
pAPU Noise Control Register 1.
pAPU Noise Frequency Register 1.
pAPU Noise Frequency Register 2.
pAPU Delta Modulation Control Register.
pAPU Delta Modulation D/A Register.
pAPU Delta Modulation Address Register.
pAPU Delta Modulation Data Length Register.
Sprite DMA Register:
Writes cause a DMA transfer to occur from CPU memory at
address $100 x n, where n is the value written, to SPR-RAM.
pAPU Sound / Vertical Clock Signal Register.
Joypad 1:
Bit 0 - Reads data from joypad or causes joypad strobe
when writing.
Bit 3 - Indicates whether Zapper is pointing at a sprite.
Bit 4 - Cleared when Zapper trigger is released.
Only bit 0 is involved in writing.
Joypad 2:
When reading:
Bit 0 - Reads data from joypad or causes joypad strobe
when writing.
Bit 3 - Indicates whether Zapper is pointing at a sprite.
Bit 4 - Cleared when Zapper trigger is released.
Only bit 0 is involved in writing.
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