NFG Games + GameSX

Genesis/Megadrive cartridge pinout

The following table describes the pinout for the Genesis/Megadrive cartridge port. With the console facing you, row A is the rearmost row, and row B is the frontmost row. Numbering starts from left to right.

pin	Name	Description	-	pin	Name	Description
A01	GND	Ground	-	B01	SL1	Sound input left
A02	5v	VCC1	-	B02	!HRST	Hard reset
A03	A08	Address 08	-	B03	SR1	Sound input right
A04	A11	Address 11	-	B04	A09	Address 09
A05	A07	Address 07	-	B05	A10	Address 10
A06	A12	Address 12	-	B06	A18	Address 18
A07	A06	Address 06	-	B07	A19	Address 19
A08	A13	Address 13	-	B08	A20	Address 20
A09	A05	Address 05	-	B09	A21	Address 21
A10	A14	Address 14	-	B10	A22	Address 22
A11	A04	Address 04	-	B11	A23	Address 23
A12	A15	Address 15	-	B12	!YS	Video
A13	A03	Address 03	-	B13	!VSync	Vsync
A14	A16	Address 16	-	B14	!HSync	HSync
A15	A02	Address 02	-	B15	HS_CLK	VCLK
A16	A17	Address 17	-	B16	!C_OE	!AS
A17	A01	Address 01	-	B17	!C_CE	!CE0
A18	GND	Ground	-	B18	!AS	Address strobe
A19	D07	Data 7	-	B19	CLK	68000 clock
A20	D00	Data 0	-	B20	!DTACK	Data ack
A21	D08	Data 8	-	B21	!CAS_2	!CAS_2
A22	D06	Data 6	-	B22	D15	Data 15
A23	D01	Data 1	-	B23	D14	Data 14
A24	D09	Data 9	-	B24	D13	Data 13
A25	D05	Data 5	-	B25	D12	Data 12
A26	D02	Data 2	-	B26	!LO_MEM	!ASEL
A27	D10	Data 10	-	B27	!RST	68K reset
A28	D04	Data 4	-	B28	!LDS	Lower data strobe
A29	D03	Data 3	-	B29	!UDSW	Upper data strobe
A30	D11	Data 11	-	B30	!SRST	Soft reset
A31	5v	VCC1	-	B31	!TIME	Unknown
A32	GND	Ground	-	B32	!C_DTCT	Cart detect - disables onboard ROM(s)

Notes:
Address and Data busses are from the 68000 perspective.
VCC1 supplies power to the 68000 and the YM2612 and possibly some other minor parts.
VCC2 supplies power to the Z80, memory and custom chips. They are generated by two seperate voltage regulators.
CLK and HS_CLK are not synchronous, just in case you want to do anything funky (like I did).