Input devices

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The NES has two general-purpose controller ports on the front of the console, as well as a (rarely used) 48-pin expansion port underneath.

The Famicom's standard controllers are hardwired to the front of the unit, and a special 15-pin expansion port is commonly used for third-party controllers. The AV Famicom, however, features detachable controllers using the same ports as the NES.

The NES and Famicom have a set of I/O ports used for controllers and other peripherals, consisting of the following:

  • One output port, 3 bits wide, accessible by writing the bottom 3 bits of $4016.
    • The values latched by $4016/write appear on the OUT0-OUT2 output pins of the 2A03/07, where OUT0 is routed to the controller ports and OUT0-OUT2 to the expansion port on the NES.
  • Two input ports, each 5 bits wide, accessible by reading the bottom 5 bits of $4016 and $4017. Reading $4016 and $4017 activates the /OE1 and /OE2 signals, respectively, which are routed to the controller ports and the expansion port.
    • On the NES, only D0, D3, and D4 are connected to both controller ports, while all of D0-D4 are connected to the expansion port.
    • On the original Famicom, the two ports differ: $4016 D0 and D2 and $4017 D0 are permanently connected to both controllers, while $4016 D1 and all of $4017's D0-D4 are connected to the expansion port.
    • On the AV Famicom, only D0 is connected to the controller ports. The expansion port is unchanged.

Programmer's reference

Hardware

Other I/O devices


Usage of port pins by hardware type

Device $4016
D4
$4016
D3
$4016
D2
$4016
D1
$4016
D0
$4016
CLK
$4017
D4
$4017
D3
$4017
D2
$4017
D1
$4017
D0
$4017
CLK
OUT2 OUT1 OUT0 /IRQ AUDIO +5V GND Note
Joypad1 x x x x x *AUDIO line can be used for pad which has audio jack to plug in headphones (for example: IQ502 joypad)
*$4016 D2 can be uses as microphone input
Joypad2 x x x x x x
Joypad3
(Famicom)
x x x x x
Joypad4
(Famicom)
x x x x x
Lightgun Zapper
(NES P2/Famicom)
x x x x *AUDIO line can be used for emiting bullet shoot sounds (for example: Casel Zapper)
Lightgun Zapper
(NES P1)
x x x x
Family BASIC Keyboard/Subor Keyboard x x x x x x x x x