Connectors

Notes

• Input mean from device (cart or megacd for example) to Megadrive.
• Output mean from MegaDrive to device

Cartridge Connector

MegaDrive Mode

Front Side				Back Side
Pin Number	Name	I/O	Description	Pin Number	Name	I/O	Description
B01	SL1	Input	Left audio from cart	A01	GND		Ground
B02	/MRES	Unknow	Active low hard (bootup) reset	A02	Vcc1	Output	Positive supply voltage (+5V)
B03	SR1	Input	Right audio from cart	A03	VA8	Output
B04	VA09	Output		A04	VA11	Output
B05	VA10	Output		A05	VA7	Output
B06	VA18	Output		A06	VA12	Output
B07	VA19	Output		A07	VA6	Output
B08	VA20	Output		A08	VA13	Output
B09	VA21	Output		A09	VA5	Output
B10	VA22	Output		A10	VA14	Output
B11	VA23	Output		A11	VA4	Output
B12	/YS	Output	Active low Mean that VDP is currently drawing the backdrop color	A12	VA15	Output
B13	/VSYNC	Output	Active low Vertical Sync	A13	VA03	Output
B14	/HSYNC	Output	Active low Horizontal Sync	A14	VA16	Output
B15	EDCLK	Output	VDP related clock, variable, changes between Mclk/5 ~ Mclk/4	A15	VA2	Output
B16	/CAS0	Output	Active low set for reads on $000000-$DFFFFF acts as /OE signal	A16	VA17	Output
B17	/CEO	Output	Active low Chip Enable set for r/w at/to $000000-$3FFFFF when cart is inserted or at/to $400000-$7FFFFF when not	A17	VA01	Output
B18	/AS	Output	Active low Address Strobe - addr bus valid	A18	GND		Ground
B19	VCLK	Output	68k clock	A19	VD7		Input/Output
B20	/DTAK	Input	Data Transfer acKnowledge for 68k	A20	VD0	Input/Output
B21	/CAS2	Unknown	Unknown	A21	VD8	Input/Output
B22	VD15	Input/Output		A22	VD6	Input/Output
B23	VD14	Input/Output		A23	VD01	Input/Output
B24	VD13	Input/Output		A24	VD09	Input/Output
B25	VD12	Input/Output		A25	VD05	Input/Output
B26	/ASEL	Output	Active low set for r/w at/to $000000-$7FFFFF	A26	VD02	Input/Output
B27	/VRES	Output	Reset from switch	A27	VD10	Input/Output
B28	/LWR	Output	Active low Lower byte WRite	A28	VD04	Input/Output
B29	/UWR	Output	Active low Upper byte WRite	A29	VD03	Input/Output
B30	/M3	Input	Active low Force Mark 3 (Master System) mode	A30	VD11	Input/Output
B31	/TIME	Output	set for r/w at/to $A13000-$A130FF	A31	Vcc1	Output	Positive supply voltage (+5V)
B32	/CART	Input	Active low set when cart is inserted	A32	GND		Ground

SMS Mode

Front Side				Back Side
Pin Number	Name	I/O	Description	Pin Number	Name	I/O	Description
B01	SL1	Input	Left audio from cart	A01	GND		Ground
B02	/MRES	Unknow	Active low hard (bootup) reset	A02	Vcc1	Output	Positive supply voltage (+5V)
B03	SR1	Input	Right audio from cart	A03	VA07	Output
B04	VA08	Output		A04	VA10	Output
B05	VA09	Output		A05	VA06	Output
B06	/CE	Output		A06	VA11	Output
B07	?	?		A07	VA05	Output
B08	?	?		A08	VA12	Output
B09	plup	Output		A09	VA04	Output
B10	pldn	Output		A10	VA13	Output
B11	/NMI	Output		A11	VA03	Output
B12	?	?		A12	VA14	Output
B13	?	?		A13	VA02	Output
B14	?	?		A14	?	?
B15	?	?		A15	VA01	Output
B16	/RD	Output		A16	?	?
B17	/M0-7	Output		A17	VA00	Output
B18	?	?		A18	GND		Ground
B19	?	?		A19	VD07	Input/Output
B20	?	?		A20	VD00	Input/Output
B21	?	?		A21	?	?
B22	?	?		A22	VD06	Input/Output
B23	?	?		A23	VD01	Input/Output
B24	?	?		A24	?	?
B25	?	?		A25	VD05	Input/Output
B26	?	?	?	A26	VD02	Input/Output
B27	?	?		A27	?	?
B28	/Wr	Output		A28	VD04	Input/Output
B29	?	?		A29	VD03	Input/Output
B30	/M3	Input	Active low Force Mark 3 (Master System) mode	A30	?	?
B31	?	?		A31	Vcc1	Output	Positive supply voltage (+5V)
B32	/CART	Input	Active low set when cart is inserted	A32	GND		Ground

Expansion connector

Front Side				Back Side
Pin Number	Name	I/O	Description	Pin Number	Name	I/O	Description
B01	GND			A01	GND
B02	VA19		Only on MegaDrive 2 boards	A02	/DISK
B03	/CAS0			A03	VA01
B04	VD00			A04	VA02
B05	VD01			A05	VA03
B06	VD02			A06	VA04
B07	VD03			A07	VA05
B08	VD04			A08	VA06
B09	VD05			A09	VA07
B10	VD06			A10	VA08
B11	VD07			A11	VA09
B12	GND			A12	GND
B13	VD08			A13	VA10
B14	VD09			A14	VA11
B15	VD10			A15	VA12
B16	VD11			A16	VA13
B17	VD12			A17	VA14
B18	VD13			A18	VA15
B19	VD14			A19	VA16
B20	VD15			A20	VA17
B21	/ROM			A21	/LWR
B22	/ASEL			A22	/UWR
B23	/RAS2			A23	/CAS2
B24	/FDC			A24	/FDWR
B25	FRES			A25	VA18		Only on MegaDrive 2 boards
B26	Vcc1			A26	Vcc1
B27	SR3		Only on MegaDrive 2 boards	A27	SL3		Only on MegaDrive 2 boards
B28	9V			A28	9V
B29	SR2			A29	SL2
B30	GND			A30	GND