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Williams Predators Flies Again! (Williams 1987 Prototype at CAX 2017)
07/29/17 06:09 PM Attachment: IMG_4205.JPG 2088 KB (2 downloads)

Williams Predators flies again at California Extreme!

Pictures here.

This machine is based around the only orignal parts i have from this game - the original game PCB set and power supplies which belong to Domonic Escott in the UK. He entrusted me with this in order that i figure out the big technical challenge that it had.

This PCB has been around for a long time, but was it missing the crucial control interface pcb that was inside each cabinet. These interface pcbs link each players' special 49-way joystick and action buttons, along with switches and cabinet buttons to the main pcb. With all of them missing, it was only possible to play at the Red - Hawk position. No paperwork is known to exist for this game so everything had to be worked out by hand.

With help from members of the MAME team, a reverse look at code interfacing the UART to the main cpu, it was determined that there was a 7-byte packet expected from each interface pcb. The exact order of the bytes (and the bits within them) and what they represented in the packet was not immediately obvious, but was worked out eventually. The added complication was the 7th byte was a'check' packet which was a calculated sum based on the contents of the other six bytes. If it was not calculated correctly, the entire packet is ignored.

After some considerable trial and error, I was able to write code for a small microcontroller (a PIC) that reads the Joystick positions, and the 4 minimum buttons needed per player for the game to function, and translates them into the 7-byte packet that the game pcb expects. This output is then converted to RS-485 and send to the respective connection on the game pcb.

The game was intended to occupy 4 FULL SIZE arcade cabinet which made the game very expensive labor intensive for the game owner requiring a large amount of space and upkeep. It was a hard sell when compared to the money generated by 4 individual games. 30 years later with the advent of flat panel monitors, it is now possible to have a single cabinet and superior player interaction.

This cabinet has been hand-made to fit four players in the most space efficient footprint that i could make for my small home-arcade. The cabinet design has developed organically over a number of years, being made from scrap wood, an old metal filing cabinet, more reclaimed parts, old LCD monitors and lots of wiring and connectors. This went from a bunch of monitors sitting on some wood balanced on top of a metal cabinet into an exhibition-ready machine largely in the last three weeks, working all day every day to work out how it was going to look, work and be durable for CAX.

Vector artwork was created from online photos by Lindy Groening, and NightVoice from the MameWorld Art Project in Adobe Illustrator and Coral Draw. Final artwork layout and control panel design was created by Trevor Brown in an exceptionally short period of time using ArchiCAD. All other technical engineering and cabinet creation work by Andrew Welburn of



Edited by TrevEB (08/05/17 03:16 AM)

Entire thread
Subject Posted by Posted on
* Williams Predators Flies Again! (Williams 1987 Prototype at CAX 2017) TrevEB 07/29/17 06:09 PM
. * Re: Williams Predators Flies Again! (Williams 1987 Prototype at CAX 2017) Dullaron  07/30/17 05:27 AM

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