gunSMS and gunNES

Light Gun adapters for the MSX

The MSX has it own Light Gun, called Plus-X Terminator Laser. It was released in 1989 and sold until 1992. You can find more info about it at the MSX-Wiki.

But since this light gun is extremely rare, a way to adapt the light guns from the Sega Master System or Nintendo Entertainment System was needed. This allows us to play the existing library and new games that happen to be developed to support it.

1) Reference pinouts:

MSX joystick port:

1	Up
2	Down
3	Left
4	Right
5	+5V
6	Trigger 1
7	Trigger 2
8	OUT
9	GND

MSX Light Gun (DE-9 connector)

1	NC
2	NC
3	NC
4	NC
5	+5V
6	Light sensor (0=dark, 1=light)
7	Trigger (0=pressed)
8	NC
9	GND

Sega Light Phaser (DE-9 connector)

1	NC
2	NC
3	NC
4	NC
5	+5V
6	Trigger (0=pressed)
7	Light sensor (0=light, 1=dark)
8	GND
9	NC

NES Zapper (Proprietary connector)

Light sensor: 0=dark, 1=light
Trigger: 0=pressed

2) How to build the gunSMS adapter:

Connect the circuit as shown.
SMSGUN schematic

DTC114 is a digital NPN transistor. Be sure that you use one with the following pinout:
1: GND
2: OUT
3: IN

3) How to build the gunNES adapter:

The NES Zapper adapter is very easy to build. It's just a mater of rerouting the signals to the correct pins.

NES Zapper	MSX
1	9
5	5
6	6
7	7

After you finished building your adapter, you can test the gun with the JoyTest utility. If everything is working properly, the light gun will be detected upon insertion and you will be able to test it. But remember: light guns only work properly on CRT monitors.

4) Credits and thanks

The original gunNES adapter was designed by Jipe and published on MSX.org
Thanks to Sturaro, for the tip about the DTC114 transistor

5) Notes

These are hobbyist projects. Build and use them at your own risk.