Atari 7800:Connector Pinouts

Cartridge Port

Note: Pins 1 through 16 are at the back and numbered from left to right. Pins 17 through 32 are at the front and numbered from right to left. Pins 3-14 and 19-30 are identical to the 2600.

Pin #	Description
1	R/W (7800 only)
2	HALT (7800 only)
3	D3
4	D4
5	D5
6	D6
7	D7
8	A12
9	A10
10	A11
11	A9
12	A8
13	5V
14	Ground
15	A13 (7800 only)
16	A14 (7800 only)
17	A15 (7800 only)
18	External Audio (7800 only)
19	A7
20	A6
21	A5
22	A4
23	A3
24	A2
25	A1
26	A0
27	D0
28	D1
29	D2
30	Ground
31	IRQ (7800 only)
32	CLK2 (7800 only)

Controller Port

Note: Female is connector at the console. Male is connector at the controller. Diagram pictured is of the connector at the controller end. Wire colors correspond to the CX24 Pro-Line joystick bundled with NTSC 7800s and CX78 gamepads bundled with PAL 7800s.

Pin #	Description	Wire Color
1	Up	White
2	Down	Blue
3	Left	Brown
4	Right	Green
5	Right Fire Button	Red
6	Combined Fire Button	Orange
7	Unused	N/A
8	Ground	Black
9	Left Fire Button	Yellow

Both fire buttons are also tied to ground via a 620 ohm resistor on each line. This setup allows for either fire button to work as a single combined fire button when used on a 2600 or other system that uses single fire button joysticks.

Expansion Port

This expansion port is only found on early NTSC 7800 consoles. Although the footprints for the port and its supporting components are present on most 7800 board revisions, they are not populated.

Note: Pins 1 through 9 are at the top and numbered from left to right. Pins 10 through 18 are at the bottom and numbered from right to left.

Pin #	Description
1	Ground
2	5V
3	Composite Video Input
4	MARIA Luma Bit 0
5	MARIA Luma Bit 3
6	Blanking
7	Oscillator Disable (disables 7800 system clock)
8	External MARIA Enable
9	Ground
10	External Oscillator Input
11	CLK2
12	MARIA Sync
13	MARIA Luma Bit 1
14	MARIA Luma Bit 2
15	MARIA Chroma
16	RDY
17	Audio Input
18	Ground