Add PSX ports to arcade games?

[Faded]

I own an arcade.

Namco recently released Tekken 5.

The dedicated machines have ports for PSX controllers.

I would LOVE to add that feature to my fighting games for my players.

Problem is, the PSX controllers send a digital signal to the console and the arcade games (JAMMA standard) use analog (well I'll get to that in a moment) signals.

Can you help me come up with a converter?

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The inputs on a run of the mill arcade game have lines that run from the board(s) to each of the individual input switches. One each for up,down,left, right and any other buttons.  I say analog because I mean that between each switch and the board there is no change to the signal. It is off and continues to be off for a duration, or it is on and continues to be on for a duration. Please do not let the analog VS digital issue at this point complicate things.

The short version is how to wire (or as I supsect more accurately) build a circuit to interface with a PSX controller port and then translate the directions and relay them to the regular machine controls.

I am not familiar with the details of the chips and adressess and data lines and so forth, but I could definitely follow directions and build some circuits!

First issue:
How to intercept the signal and determine what command(s) is/are currently being issued from the controller.

Next:
How to interface that signal with the regular controls?
I am thinking that perhaps the signals could be routed to transistors connected to the tabs of the existing switches and the ground lines. When the transistors are idle, nothing would happen. But when the enable line is tripped then the switch (as seen by the game PCB) is closed. (Obviously one IC could contain all the necessary transistors.)

It would also be advantagous to include a small circuit to effectively disable (disconnect) the control panel's regular ground line whenever a PSX controller is plugged in. This would prevent someone from tampering with the player's moves while they are trying to use their console controller.

So what would be needed? Here are some of what I think I understand would be involved:

-Something to provide a clock signal and power

-A pretty much continuous request for the controllers data

-Chip(s)/circuit to read the data and translate back to individual signals

-Driver circuit(s) to relay those signals and interface them to the existing controls

Note(s)
JAMMA by definition has available +5VDC, +12VDC and most machines have negatives available as well.
The boards would have clock signals on them, but they would vary greatly I would think and also would require hardwiring to the PCBs, yuck! Hardly worth mentioning, but just making it clear that since there will NOT be an entire Playstation inside* something has to provide it.

*I can get a steady stream of 'dead' PSXs for parts. The controller ports are the obvious ones, but perhaps there is a lot more in them we could scavenge.

I doubt that this is the case, but there wouldn't be points inside a PSX that could be tapped directly for this purpose are there?  Figured I'd ask just in case it could save a lot of time and work!

Any information appreciated.  I have the solder station, time and motivation, I just need someone with the  experience and knowledge to finish the equation.

Thanks!

-faded

[NFG]

Lik-sang.com sells a PSX->Neo convertor, and the neo uses one pin for each button or direction.  Seems to me this would be the easiest way to do it.

Making a PSX decoder would require a micrcontroller, supporting circuitry, and a fairly complicated program running on it, something that would involve a lot more than a soldering iron and a bucket of parts (Which is the reason I haven't done it...)