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Williams games were designed around the Motorola 6800 series of chips. Also contained on the MPU board are the game's ROM (Read-Only Memory) chips that contain the game specific program. The diagnostics on a Williams MPU board consists of two LEDs. A common mis-conception is that Williams boards do a 'self-test' like the boards from other. In some ways, Williams is a good company, but it is exceptionally biased. I was recently told, by several on a hiring team, that it is nice to have someone 'like me' getting the job I put in for. Not so subtly, the point was made that I got the job primarily because I was an 'under represented group.' Buy used and new pinball machines, arcade games and table games online at The Pinball Company, with free shipping on select machines! Skip to content 1.877.574.6225.

This portion of my web site is devoted to the classic Williams gamesof the early '80s- Defender, Stargate, Robotron, Joust, Bubbles and Sinistar.I have a Joust machine that has been modified to play all of these games,and much of the information that I have gathered over the last couple ofyears has been compiled here.

Please leave me feedback if you find any errors or know of any omissions: seanriddle {at} airosurf {dot} com

Please read my FAQ before emailing me a question-it's probably in here!

This page up since 6/15/95.

Note: graphics and sounds from the games are copyrighted by WilliamsElectronics. The programs and schematics are public domain, although I wouldlike to be notified if you will use them for commercial purposes.

Contents

News

Galaxian Disassembly

Now Scott Tunstall is disassembling Galaxian's code. Keep checking for updates.

Splat! Patch 2

I was asked about the Splat! patch, so I did some more research

Robotron Disassembly

Scott Tunstall has been disassembling the Robotron ROMs. Keep checking for updates.

using an SC1 in place of an SC2

Special Chip 2s are hard to find, so here's an adapter to use an SC1 instead

a peek inside the 55516 CVSD IC

Die shot of the 55516 CVSD voice encoder/decoder used for Sinistar speech.

in-depth Special Chip info

More info than you want to know about the blitter chips, including a decap

MAME as a hacking tool

Williams Video Game Company

MAME is an excellent tool for hacking video games.

Logic Timing

I connected a Logic16 analyzer to various timing signals on my Joust board to illustrate the relationships between different clocks.

Williams Emulation Test Suite

I began writing a test suite to help out everyone writing Williams emulators or recreating Williams games in FPGAs.

graphics ripper

I rewrote my graphics ripper in Visual C++. Here are some pics and technical info, along with the program and source.

removing the lines from the top of the screen

Here's an explanation of those lines you see at the top of your game, and how to remove them.

notes on patching ROMs

Here are some tips on patching ROM images

6800 disassembler

I wanted to look at the Sinistar sound code, so I modified 6809dasm to disassemble 6800 code. I've also posted a preliminary .dat file for Sinistar.6800dasm

new multigame hardware

Again, it's been a long time, but I've built new multigame hardware. Take a look here for details.

Up what? What date? What what?

Wow, it's been a long time, but there are a few new things. RoboMax - a patch for Robotron to remove the 5-high scores limit.

New executable programs recompiled to work under Windows.

I got the Playstation games Williams Arcade's Greatest Hits, Atari Anniversary Edition Redux and Namco Museum, so I built a control panel.

shockwave arcade games

shockwave.com recently added ten classic Midway arcade gamesthat include Defender, Joust, Spy Hunter, Rampage, Robotron 2084, Defender II, Sinistar, Bubbles,Tapper and Satan's Hollow. Digital Eclipse converted these from their CDs.

FAQ

I've written a FAQ to help answer some of thequestions that I'm asked over and over again. Please read it before askingme a question. Thanks!

Blitter Test Files

I've uploaded a set of files that demonstrate the use of the Williamsspecial chips. These files are named BLITTEST.*. I've got a program, its6809DASM .dat file, the RAM dump and a .gif. Here they are.

Lotto Fun

Thanks to Lawnmower Man and Mike Balfour, I got Lotto Fun- a 'pingpong balls in a blower' type lottery game. It is copyright 1987 H.A.R.Management Inc. If anyone knows anything about them, please let me know.It is an interesting game- nice fonts, good colors, color cycling, screenfades. It uses the CMOS RAM for adjustments and bookkeeping totals. It workson a Bubbles setup, but only uses the 1 player start button. It will workon Robotron, using just one of the joysticks and the 2 player start button.It won't work on Sinistar, Defender or Stargate, but would work on Joust,although you can't move left or right. You choose 3, 4, or 6 numbers tomatch, then you win from 5-5000 tickets or tokens if you match. Of course,I don't have a ticket dispenser, so I get the message 'CALL OPERATOR' whenI win, and I have to clear it with the advance button. I was also able toget it to run in MAME as Bubbles and Robotron, although the colors are wrong,it doesn't color cycle, and it hangs after the reset screen. You can getit to go past by holding down the '5' key, but you can just see the demo,not play. I've got screen shots and a 6809DASM.dat file.

New look

Hey, I tidied this place up a bit and fixed some of the out-of-date links.Sorry it took so long.... I also fixed my page counter again. Please letme know if something doesn't look or work right.

Cinematronics MultiGame started

Look for a new page soon.... I got a Star Castle, and I've begun workon a multigame. I'm attempting to use a single 27C040 which would give meroom for up to 16 32K games. Of course, I've got to work on the controlpanel, and the sound boards are going to be a big problem. I also have abad high voltage unit which is slowing me down a lot. If you have a KeltronHV unit for sale, please leave me email. I'd also like to borrow some soundboards to digitize the sounds, and I'd love to get a copy of Tail Gunner'sschematics. Thanks!

SRAM mod

Williams Game Company Stock

Tired of changing batteries every 6 months, I replaced my SRAM with aDallas chip that has a self-contained battery. It is a straight swap forthe 6264 that I was using. All I did was yank the batteries from the CPUboard.

Defender Hack II

I added 3 more chips to my Joust machine to make it more similar to Defender'shardware so that I can run Defender without any ROM hacks. Well, I actuallyhave to clear 3 bits(!) so that the sound board will work. And there isa slight graphics glitch during the rug RAM test until the demo starts,but then everything is perfect.

Williams Arcade Classics Win95

I just got my copy of WAC Win95. In addition to the new versions of thegames, it includes the DOS versions. The new versions use seperate uncompressedROM images, making hacking easier. The sound files are .wavs, so you canplay around with those as well. Look for some hidden goodies! I found somethingthat I'd been wondering about for a while. Also look for me under 'betatesters'!

Counter Overflow?

My hit counter on this page had somehow reset. I'm not sure exactly how,but I counted the entries in my hit database, and updated my counter.

Z80 disassembler

I've posted the source code for my Z80 disassembler on my Midwaypage. This program is very similar to my 6809 disassembler, with supportfor distributable data files. Please send me any you create!

PC Executable Programs

I've finally compiled my software for the PC. I've posted the .exe filesalong with the source code.

Splat info!

Splat is an (almost) unreleased Williams game from 1982. It runs on nearlythe same platform as the other Williams games of that era, except that itexpects Special Chip 2s instead of SC1s on the ROM board. I've posted abunch of pics from the game, as well asa software patch to use SC1s. There is acircuit in the hardware section that letsyou use SC1s without the software patch. Splat is sort of a cross betweenRobotron and Food Fight. You chunk pies, apples, fish, bananas and otherfood items at your foes (and the other player, in a 2 player game). If youare hit, your head flies off and you must recapture it before you can throwany more food. If you are hit without your head, you lose a life. Splatis wave-based, like the other Williams games, but is unique in that thewaves are timed. You can grab food as it falls from the top of the screen,and if you time it right, you can grab food thrown at you. There are alsokeys that you can throw, or use to go through one of the four doors (2 oneach side of the screen) that take you to the other side.

Pterodactyl-bug Joust Patch

I've posted a patchfile to modify theJOUST.EXE game of Williams Arcade Classics from the green ROM image to theyellow image. This ROM revision has the well-known 'pterodactylbug'. You can find the patchfile in the softwaresection.

New Utility Programs Added

I've made available several utility programs:

uncomp.c - source code to uncompress the Williams Arcade Classics ROMimages

splitter.c - source code to a file splitter - convenient for splittingROM images

joiner.c - source code to a file joiner

You can find them in the software section.

Bug-fixed Robotron Patch

It is fairly easy to patch the blue-labelled Robotron ROM image to removethe 'shot-in-the-corner' crash. I've posted a patchfileand a program that can make patches using a patchfile. You can find themin the software section.

Digital Arcade's Williams Arcade Classics

Williams Game Company Logo

Well, the games are out now for DOS. You get Defender, Defender II, Roboton,Joust, Bubbles and Sinistar for about $35. The games use a 'Williams Emulator' to run the actual arcade game code, so they are very authentic.

You can check out info here.

Software ROM Switcher Built

I used the parallel port (see below) to control the 3 game select addressbits on my Multi-Game EPROM. I wrote 6809 code that I burned into game position0 of the EPROM that puts up a picture, displays graphics from one of thegames, and plays a sound. Then it waits for the player to hit the 1 or 2player start button; when the 1 player button is hit, the graphics are updatedto the next game and a different sound is played. When the 2 player buttonis hit, the correct ROM image is selected, and the reset vector jumped to.This starts the game at the normal 'rug' RAM test. When the reset buttonis hit, the parallel port latches are cleared, and my ROM switch code isrun again. I put up a picture in the Multi-Gamepictures section, and the code and a .DAT file for my 6809 disassemblerare both in the Software section. NOTE- toaccomodate the Robotron bug fix, I had to change the hardware address ofmy port. The code and schematics have been updated. I added the abilityto load a game's CMOS RAM, so you can restore high scores that have beencleared. I also added a function to trash CMOS RAM so you can get the machineto reset EVERYTHING to defaults.

8-bit parallel Port Built

I added two 4-bit latches and a simple address decoder to my Multi-Gamemachine to create an 8-bit parallel port. I wrote 6809 code to dump thecontents of RAM to my Amiga using a simple handshaking protocol. I thenmodified my graphics scanner to display the screen dumps. I've added a newsection of pictures, and the port is describedin the conversion section.

Speech PCB artwork available

Frederic Vecoven has taken the Speech board schematics and has laid outa printed circuit board. Here's the link.

Special Chip hack finished

I have made a small circuit that allows Special Chip 2 ICs to be usedin games that require the Special Chip 1, and vice versa. See the conversion section.

Sinistar Speech Board Built

Paul Astrachan located some 55564 ICs that are pin-compatible with the55516s used on the Williams speech board. I built the speech board, usinga 27128 to hold the ROM image from the 4 EPROMs. I used a 7408 to decodethe 4 EPROM select signals into *CE, *OE, A12 and A13. The hard part wasthe analog side: too many caps and resistors! But it works, and I now hear'I hunger!', 'Run Coward!' and all the rest. You can find a picture of myspeech board in the pictures section andthe schematic of the EPROM addressing circuit in the conversionsection. There's also a link to Harris' online 55564 data sheet.

Defender added to my Multi-Game machine

With a combination of hardware andsoftware hacks,I have finally gotten Defender up and running on my Multi-Game machine.The hardware implements the bank-switchingcircuit that Defender used to access 7 of its ROMchips. The software patches change the references to the ROM and WidgetPIAs,the Watchdog and the CMOS RAM to the addressesused on the newer games.

BTW- the .gif file of the hack had a small error- the gateshown going to the 74157 pin 2 is supposed to be an ORgate, not a NOR gate. The schematichas been fixed. Thanks to Paul Astrachan for noticing.

Sinistar added to my Multi-Game machine

I have gotten Sinistar up and running on my Multi-Game machine, joiningJoust, Stargate, Robotron and Bubbles. Two circuits have to be added tothe ROM board: a clipping circuit for the blitter chips and SRAM in placeof the Dxxx EPROM. Also, the control interface board has to be modifiedslightly.

Thanks go to Lee Crawford for his excellent joystick hack.

Digital Eclipse presents Williams Digital Arcade

Digital Eclipse (510-450-1740) has released three classic Williams gameson the Macintosh. Defender, Robotron and Joust are exact duplicates of theoriginal games because they use the real ROMimages, running on an emulator.

The games start out with the 'rug' RAM test, then'All Systems Go'. You can even enter the Bookkeeping mode and Setup screen.High scores and game settings are saved to a diskfile between sessions.

I purchased Robotron, and am quite pleased with it. It was $30 with shipping.I was surprised to find out that it comes with the older (yellow w/orangestripe) ROM image, since I heard that Joust comes with the newer, non- 'pterodactyl bug' ROM image. (It was easy to hackthe Joust ROMs into Robotron, though!)

Game play is pretty good on my 40MHz 68040 machine, especially in 16color mode. Since all the Williams games only had 16 colors, 256 mode isoverkill. With a 480-line or taller display, you can double the pixel sizeto make the game normal sized. Otherwise, it's kind of hard to see what'shappening.

Public policy decisions can affect Williams’ businesses and it is in the best interest of the company, its employees and stakeholders to be engaged in the political process at the federal, state and local level. Williams participates in the political process through contributions from the Williams Political Action Committee (WILLCO PAC) and through company contributions where legal and appropriate under state law.

Williams has guidelines governing contributions which include prior written approval by the company’s executive officer team. All political spending will reflect the company’s interests and not those of individual officers or directors. No contribution will be made in anticipation of, in recognition of, or in return for an official act by the recipient of the contribution. The use of company funds or assets for political purposes must be approved through the government affairs department which, among other things, will obtain legal department confirmation that the proposed use is permissible under federal, state or other applicable law.

As part of its oversight role in public policy, the Nominating and Governance Committee of the Board of Directors reviews, at least annually, the company’s political contributions including spending related to trade associations and other tax exempt organizations. The Board also reviews spending guidelines.

Corporate officers are available for any questions pertaining to policy or procedures, purpose and spending. Federal law prohibits companies from contributing to candidates for federal office, but many states allow corporate contributions to state and local candidates, committees and political organizations and, where allowed, Williams may make such contributions. As described in the company’s code of conduct, any contribution of company funds or the use of other assets for political purposes must be approved in advance by the company’s executive officer team. Political contributions made with company funds outside the United States must be approved by the company’s executive officer team and the legal department. Click on the years below for our archive of political corporate contribution reports:
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Williams and WILLCO PAC make bipartisan contributions to political candidates and initiatives that support the advancement of the company’s interests and the interests of the industry in which Williams operates. In determining which candidates and initiatives to support, Williams and WILLCO PAC balance the views promoted by a candidate or ballot initiative, the qualifications and effectiveness of the candidate or organization to which the contribution is made and the appropriateness of the company’s level of involvement in the election or ballot initiative. With respect to particular candidates, among other factors, the company considers the candidate’s:

• Understanding of our industry and support for our positions on issues concerning our businesses;
• Position on key committees that consider legislation critical to our business interests;
• Leadership position or potential for leadership;
• Representation of districts or states where Williams employees or facilities are located; and
• Viability as a successful candidate.

Williams belongs to a number of trade associations at the national, state and local levels. Williams will disclose all expenditures of corporate funds to these associations used for non-deductible lobbying and/or political expenditures under Internal Revenue Code Section 162(e). Click on the years below for our archive of these expenditure reports:
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Political Action Committee

Williams has a political action committee, WILLCO PAC. WILLCO PAC is a voluntary fund supported by Williams employees who choose to participate in the political process by pooling their resources to elect candidates who support a free and competitive economic system and who understand and support the interests of our businesses.

WILLCO PAC is an independent, non-partisan entity that raises voluntary contributions from eligible Williams employees and supports candidates for Congressional office and for state office, where Federal PAC contributions are permitted by state law. Contributions to certain national party organizations may also be made as appropriate. Employee participation in the WILLCO PAC is strictly voluntary and employees have a right to refuse to participate without fear of retaliation or reprisal. The company will not pressure or coerce employees to make personal expenditures in support of the PAC or take any retaliatory action against employees who do not participate. Employees who participate in the PAC will not be reimbursed for their contribution or any other personal political expenditure.

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Contributions to the PAC are subject to written guidelines. Recommendations for contributions are prepared by the vice president of government affairs, who reports to the General Counsel and presented to the executive officer team for approval. The Federal Election Commission regulates WILLCO PAC’s activities. Reports detailing its activities are available on the FEC website.

Lobbying Disclosure

Federal and state law requires Williams to report expenditures associated with activities that support lobbying. This includes expenditures associated with the activities of our employees and payments made to external entities and trade organizations. It is the responsibility of employees engaged in these activities to report their time at the required reporting intervals. Information on these activities and associated expenditures is available for public inspection on the U.S. House of Representatives website.

Gift Rules

There are very strict rules pertaining to gifts to Executive and Legislative Branch employees and to state legislators and their staff. It is the responsibility of all Williams’ employees to know that rules regulate this conduct, that there are penalties for non-compliance and that full compliance is expected. There is a ban on the giving of gifts due to the potential appearance of impropriety, the complexity of the rules and the potential for mistakes.

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Williams makes reasonable efforts to track and report payments made to trade associations and other tax exempt organizations that may be used for political purposes, such as lobbying activities that would not be deductible under section 162(e)(1) of the Internal Revenue Code. The following trade associations and tax-exempt organizations have informed the company that the following dollar amounts of our membership dues were used in support of lobbying activities and are not deductible. Lobbying activities do not include contributions to political campaigns.