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Joust to JAMMA conversion (C) 1994 Graham Bisset

Your attention is drawn to the following VERY IMPORTANT legal and copyright information :


Although I've made every possible effort to ensure the information contained within this document is precise, it may still be error ridden. However even if is not, you may still damage your equipment, your machines or even yourself by using the information contained herein. I make no guarantee of ANY kind; USE THIS INFORMATION AT COMPLETELY YOUR OWN RISK. I will *NOT* be held responsible nor liable for any damage or injury resulting from any use of this document or the information in it. If you are unsure about your ability to perform this conversion, then STOP! and seek the advise of a professional.

Copyright information
The information which is given herein has been gleaned from the Williams Joust instruction manual and my personal experiences while doing this conversion. The only information which has been taken is information on what each pin on each connector does. No other information has been taken nor has any reproduction of any schematics been done. All my own ASCII !

Distribution Information
This document is (C) Copyright 1994, Graham Bisset. You are free to copy and/or distribute this document as long as it remains INTACT with all copyright notices and my name attached. You may upload this document to any information resource eg bulletin board, USENET news, FTP sites etc that you think appropriate, again as long as it remains intact. If any of this information is to be entered into a publication, that is ok, so long as I am notified of this before the article is printed and full credit is given.

Also, you may NOT change or add to this document without my EXPRESS permission. However, I will look on any changes favourably. Personal (private) use is unconditional so long as the ENTIRE text is included.

Document information
This document gives information on how I converted a Williams 'Joust' Game from the Williams format to JAMMA standard so that the game could be played on my Electrocoin Goliath cabinet.

This conversion I would rate as : Easy. The hardest part is having the patience to make up so many cables to go from the board to the JAMMA connector. You are going to need approximately 40 pieces of cable to connect between the boards and the JAMMA connector. Other items you'll find useful are a IC socket for a 14 pin IC, a single push button and a small switch. You'll also need a 74LS04 for the monitor conversion and a JAMMA connector and *plenty* of cable.

I suggest that you read and then re-read this document BEFORE you attempt the conversion.

Right lets get started. Joust consists of 4 boards, the main cpu board, the ROM interboard containing all the game ROMS, the input interface board and the sound board.

The first thing to do was to find an appropriate sized piece of wood to hold all the boards in such a way as to make the interconnections easy. Having acquired the wood I layed out the boards as below :

|  -----------------------     ----------------    |     
| |                       |   |                |   |     
| |  CPU board            |<->| Main ROM board |   |                 
| |                       |    ----------------    |     
| |                       |    ---------------     |
| |               =  =  = |<->|Input Interface|    |     
| |  +++          =  =  = |    ---------------     |           
| |  +++          =  =  = |    ----------------    |               
| |  +++          =  =  = |   |                |   |
|  -----------------------    |  Sound board   |   |
|                             |                |   |
|                              ----------------    |

Interface : Input Interface
=         : RAM chips
+         : Batteries
<->       : Link between boards with a ribbon cable

This gave excellent access to all the boards connectors' and made everything reasonably neat and tidy (a must! :-))

Now we have the diagram again, this time I have given the location of each connector a number.

|  --1------------2-------     ------------3---    |     
| |                       |   |                4   |     
| |  CPU board            |   | Main ROM board 5   |
| |                       |    ----------------    |     
| |                       |    ---------           |      
| |               =  =  = |   |Interface|          |     
| |  +++          =  =  = |    ----6----           |
| |  +++          =  =  = |    ----------------    |
| |  +++          =  =  = |   |                7   |
|  -----------------------    |  Sound board   8   |
|                             |                9   |
|                              ----------------10  |

Aha you say, you've forgotten about the other connector between 1 & 2, well actually I haven't. I dont use it, in the manual it tells me its the 'Memory Protect Interlock', since I dont have the original cabinet, I figure this is not much use to me. I'm waiting for someone to prove me wrong though :-)

One *very* important thing to remember. You MUST and I repeat MUST ground every board together, its up to you how you do this, there are essentially two ways. Take a wire from one of the screws on each board and hook it to the next nearest board, after you've done all of them solder that wire to one of the grounds on the JAMMA connector. THIS IS VERY IMPORTANT!!!

Ok, perhaps the easiest thing to start with is connecting number 5 to 7 since it involves no external connections.

Connector 5 has 9 pins, pin 1 is the key pin (to stop you putting the connector in the wrong way round) and pin 9 is not connected. So from top to bottom the connectors looks like this :

Connector 5                                   Connector 7
-----------                                   -----------
 o  - Pin 1 (Key)                              o  - Pin 9 (N/C)
 o                                             o
 o                                             o
 o                                             o
 o                                             o
 o                                             o
 o                                             o
 o                                             o
 o  - Pin 9 (N/C)                              o  - Pin 1 (Key)

The pins are numbered this way as if you're looking down on top of them as shown in the diagram above. So for wiring this up you start at pin 2 on connector 5 and connect it to pin 2 on connector 7, pin 3 to pin 3 and so on. All fairly straightforward stuff.

Right lets move on to the power to the board. Every board with the exception of the interface board, needs power. You will notice that on each connector there is more than one connection for power input of the same voltage, the first thing I though is that you didn't need to wire up every one, as long as there was one connected it would be ok! WRONG! Each one *needs* to be connected. :-)

Right connector one needs +5v to pin 7, -5v to pin 9 and +12 to pin 5. The easiest way to do this is take these connections direct from the JAMMA connector, so take the appropriate pins from the JAMMA side and wire to connector 1. Ground is taken from pins 2 & 3 and pin 4 is a 'key' pin.

Connector 3, pin 1 is ground, pin 4 & 6 are +5v.

The only other connector which requires power is number 10. Pin 2 is +12v, pin 3 is +5v, pin 5 is ground, pin 8 is -12v. Now on most JAMMA cabinets there is a distinct lack of -12v. So what I did was wire it to -5v. This doesn't create too much of a problem as long as the volume is kept low, in practice you'll find that you can have the volume at a good level without any problems.

Lets move on to the subject of monitors. Here is where there is a little bit of work required. First off, the monitor outputs are taken from connector 2, starting from pin 1 we have :

Pin 1 - Red               
Pin 2 - Green
Pin 3 - Blue
Pin 4 - Video Ground
Pin 5 - Horizontal Sync
Pin 6 - Vertical Sync
Pin 7 - Composite Sync

The existance of this Composite Sync on pin 7 is not documented in the 'Interboard Wiring' of the manual but it does exist, I can assure you. So wire the corresponding pins above to the correct ones on the JAMMA connector. If you use pin 7 then you must feed this line through a hex invertor. You can get these as 74LS04 chips. I'd also advise you buy a chip socket for it, rather than having to solder direct on to the legs of the chip.

If you look at the chip from above it will look like this :

    -_-        What you need to do is this, wire pin 7 to ground 
1 -|   |- 14   pin 14 to +5v, pin 1 FROM connector 2 (pin 7) and
  -|   |-      pin 2 now is the inverted sync line so take this
  -|   |-      to the JAMMA connector (Sync pin 'P')
  -|   |-
  -|   |-
  -|   |-      BTW, the -_- denotes the notch in the chip
7 -|   |- 8    (I never was any good at ASCII drawing :-))

Now on to the input decoder, this is the smallest board of them all with 2, 10 pin connectors. Assume that the side furthest from the cable feeding to the main board is pin 1. So that gives us :

Pin 2 - Player 2 move left
Pin 3 - Player 2 move right
Pin 4 - Player 2 flap

All the rest in the first bank of 10 are not connected.

The second connector (pins 11-20) is :

Pin 11 - Player 1 move left
Pin 12 - Player 1 move right
Pin 13 - Player 1 flap
Pin 15 - 2 player start
Pin 16 - 1 player start
Pin 20 - Ground

Right lets push on to the sound board. Connector 9 is where its at, by now you are nearing completion only a few things to do. Connector 9 is easy. Pin 1 is furthest *away* from the dip switches and push button. Pins 1 and 4 are used here. Pin 1 should go to SPEAKER + and pin 4 to speaker - (MINUS) on the JAMMA connector (10 and 'L' on JAMMA respectively).

The next thing is volume, well for a short term measure I simply put a 1 Meg Ohm resistor over pins 1 and 2 of connector number 8, but you should really add a potentiometer. Unfortunately I cant give you a figure for this as the docs I have dont give the information readily. :-(

Right, last but no means least is the switch and button that are used for the 'Auto up/manual down' and 'Advance' respectively. For the switch take pin 1 (furthest from the LED) and any nearby ground to the pins of the switch.

For the advance button use pin 2 and another suitable ground. You should find that that is all you need for this part. The other pins on that connector (number 4) are :

Pin 3 - High score reset button
Pin 4 - Left Coin
Pin 5 - Centre coin
Pin 6 - Slam (???)
Pin 9 - 'Key'

You'll notice that I didn't mention about pin 3, this is because on my setup I didnt add this, partly due to the fact that I dont want to make it easy to reset the scores. There, thats logical isn't it?? ;-)

I dont use the coin switches since I have a switch in line with the coin mechs on the cabinet, so all I need to do is push that. I have also set the game into 'FREE PLAY' mode. Sorry but I cant give you any information about setting up the coin parts.

Thats you ready to fire up the game and test it, if you get RAM errors then you may want to have some spare RAM handy to swap it out with. But I STRONGLY advise you to check your power supply first. My board was EXTREMELY unhappy at having more that +4.7v (wasn't it Gregg!) the game would run, the 'All systems go' message would appear and you could play a (short) game, but it would always crash. The problem was very strange but once I turned down the power a bit, it worked fine.

If you dont get anything on your screen, make sure that you've wired up your 74LS04 correctly. I believe these are static sensitive devices so be careful and exercise the correct precautions when handling them.

Well that about wraps it up, essentially this is an easy conversion, the hardest part, like I say, is having the patience to strip all those wires and make the connections. But if you're determined to do it, nothing will stop you!!

I hope this information has been of use to someone. I know its written in a very simplistic style but it was my intention to make it easy for a complete beginner to understand, I hope no-one you have not been offended by me writing in this manner. If you have, then you have my apologises.

Ok well, if you want, let me know how you get on. I'd be interested in hearing if you found the information useful or not. You can contact be on the address below.

Cheers & Good Luck!

Graham Bisset



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