SG-1000:Connector Pinouts

Cartridge Port

Note: Pins A1 through A22 are towards the back and numbered from left to right, B1 through B22 are towards the front and also numbered from left to right. On the SC-3000, A1 through A22 are towards the bottom and B1 through B22 are towards the top.

Pin #	Description	Pin #	Description
A1	A0	B1	5V
A2	A1	B2	5V
A3	A2	B3	!OSRAM (SG-1000 and SC-3000) / !CSRAM (SG-1000 II)
A4	A3	B4	!EXM1 (SG-1000 and SG-1000 II) / !CEROM (SC-3000)
A5	A4	B5	!RD (SG-1000 and SG-1000 II) / !MEMR (SC-3000)
A6	A5	B6	!WR (SG-1000 and SG-1000 II) / !MEMW (SC-3000)
A7	A6	B7	Unused (SG-1000 and SG-1000 II) / I/O R (SC-3000)
A8	A7	B8	Unused (SG-1000 and SG-1000 II) / I/O W (SC-3000)
A9	A8	B9	!RFSH (SG-1000) / Unused (SC-3000 and SG-1000 II)
A10	A9	B10	!MREQ
A11	A10	B11	CONT
A12	A11	B12	Unused (SG-1000 and SG-1000 II) / !RAS1 (SC-3000)
A13	A12	B13	Unused (SG-1000 and SG-1000 II) / !CAS1 (SC-3000)
A14	A13	B14	Unused (SG-1000 and SG-1000 II) / RAM A7 (SC-3000)
A15	D0	B15	Unused (SG-1000 and SG-1000 II) / !RAS2 (SC-3000)
A16	D1	B16	Unused (SG-1000 and SG-1000 II) / !CAS2 (SC-3000)
A17	D2	B17	Unused (SG-1000 and SG-1000 II) / !MUX (SC-3000)
A18	D3	B18	A14
A19	D4	B19	!EXM2 (SG-1000 and SG-1000 II) / A15 (SC-3000)
A20	D5	B20	!M1 (SG-1000) / Unused (SC-3000 and SG-1000 II)
A21	D6	B21	Ground
A22	D7	B22	Ground

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. This pinout is mostly identical to the later Sega Master System and Mark III.

Pin #	Description
1	Up
2	Down
3	Left
4	Right
5	Unused
6	Button 1
7	Ground (console side only on SG-1000 and SG-1000 II) / Unused (SC-3000 only)
8	Ground
9	Button 2

Expansion Port

This expansion port is only found on the SG-1000, SG-1000 II and Othello Multivision consoles.

Note: Pins are numbered from left to right with the edge of the connector facing forward.

Pin #	Description
1	Ground
2	Ground
3	Ground
4	Ground
5	A2
6	Unused
7	IOREQ
8	CONT
9	Write
10	Read
11	KBSEL
12	D7
13	D6
14	D5
15	D4
16	D3
17	D2
18	D1
19	D0
20	A1
21	A0
22	Unused
23	5V
24	5V

SC-3000 Monitor Out

Note: Female connector is pictured. The same pinout is also used on the Master System and Genesis/Mega Drive.

Pin #	Description
1	Composite Video Out
2	Ground
3	Audio Out
4	Unused
5	Unused

Yeno SC-3000 Monitor Out

Note: Female connector is pictured.

Pin #	Description
1	Composite Sync
2	Ground
3	Audio Out
4	Vertical Sync
5	Horizontal Sync
6	Green
7	Blue
8	Red