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 | ||||