[cmjones01]

This isn't conventional fare for this forum, but I thought some people might be interested. One of my technical interests is classic arcade games, mostly from the early 1980s. They're great curiosities: though based round 8-bit microprocessors, every single one has different special hardware for creating its own particular graphics and sound. Each game has its own circuit boards which can only play that game. At the time, to me as a child, they seemed amazingly sophisticated.

Of course, these days it's easy to recreate the games in an emulator on a modern PC or even mobile phone, but where's the fun in that? A PCB covered in sweating TTL chips has much more character, and fault-finding them is always a challenge.

A necessary tool for running the boards is some means of getting power and joystick connections in, and sound and video out. The boards generally run from +5, +12 and sometimes -5V supplies, and produce RGB video at some approximation of standard 525-line or 625-line timing. They usually drive a speaker directly. Every board from this era has its own connector. Often an edge connector, sometimes Molex connectors or something else.

As luck would have it, later in the 1980s after the boom in arcade games had faded, a standard emerged for game board connections: JAMMA. It's a 56-way edge connector which carries all the relevant wiring. It's convenient, therefore, to make adapters which wire old boards to the JAMMA standard, then they can all plug in to one device: a supergun.

A supergun? What's that? For some reason, it's the term used for a box which takes a JAMMA connector and splits it out into video, audio, power, joystick and other connections. This is mine.

It's mostly a box of sockets and wires with a power supply in, but has the following features:
- switch-mode mains power supply giving +5, +12, and -5 volts
- connections for joysticks on the Atari/Sega 9-pin connector or Neo Geo 15-pin connector
- built-in speaker
- switches for putting the board in service mode and switching off the speaker
- buttons for adding a coin (of course) and starting the game
- 6-pin DIN RGB output like the BBC Micro, to connect to Microvitec monitors like the one on my workbench
- SCART sockets, in and out, with the video and audio levels attenuated to suit. Relays are used to pass through another video source when the supergun is switched off, just as a well-behaved SCART device should.

The wiring is, I'm afraid, a ratsnest, but it works well enough.

I've attached some pictures so you can see the outside and inside, and lastly one of it in action running 'Moon Patrol', a classic on a stack of 4 PCBs. They don't make them like that any more.

Chris