NES Expansion port

Available at Nintendo NES. Located under the console.

Pinout

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Pin	Direction	Name	Description
01		VCC	+5 VDC
02		GND	Ground
03		AIN	Audio In
04		/NMI	R/W or NMI?
05		CA15	Address 15?
06		C 51	Connected to Cartridge port pin 51
07		C 52	Connected to Cartridge port pin 52
08		C 53	Connected to Cartridge port pin 53
09		C 54	Connected to Cartridge port pin 54
10		C 55	Connected to Cartridge port pin 55
11		/C2R	OE for stick 2?
12		C1.1	Player #1 D1
13		C1.3	Player #1 D3
14		/IRQ	Interrupt
15		C2.2	Player #2 D2
16		C2.3	Player #2 D3
17		/C2R	OE for stick 2?
18		C2.4	Player #2 D4
19		C2.0	Player #2 D0
20		C2.1	Player #2 D1
21		AOUT	Audio Out
22		VOUT	Video Out
23		VDD	+9 VDC
24		4MHZ	4 MHz clock
25		D7	Data 7
26		D6	Data 6
27		D5	Data 5
28		D4	Data 4
29		D3	Data 3
30		D2	Data 2
31		D1	Data 1
32		D0	Data 0
33		C1.2	Player #1 D2
34		/C1R	OE for stick #1?
35		C1.0	Player #1 D0
36		C1.4	Player #1 D4
37		/C1R	OE for stick #1?
38		C 20	Connected to Cartridge port pin 20
39		C 19	Connected to Cartridge port pin 19
40		C 18	Connected to Cartridge port pin 18
41		C 17	Connected to Cartridge port pin 17
42		C 16	Connected to Cartridge port pin 16
43		C.0	Out0 (from CPU, strobe on sticks)
44		C.1	Out1 (from CPU)
45		C.2	Out1 (from CPU)
46		N/C	not connected
47		GND	Ground
48		VCC	+5 VDC

Note: Direction is console relative attached device.

Caution 1: Pin 21 and 22 may be swapped!

Caution 2: Direction show above may be unreliable.

Contributions

• Joakim Ögren

Sources

• NES hardware development guide (April 23rd, 2004) by Brad Taylor
• NES Cart Types by Kevin Horton