Conversion FAQ



REVISION DATE: 02 November 1994

     (02/11/94 - Clarified technical details in {6.4}, Added a few words on
     manuals in {7.3} and analog controllers in {8.1.3})
     (01/11/94 - First public release; FTP only)

     Doug Jefferys, Steve Ozdemir

WWW version by Frederic Vecoven (veco@montefiore.ulg.ac.be)

     Wayne Aiken, Graham Bisset, Duncan Brown, David Hanes, Tony Jones,
     John Keay, Patti Ozdemir, Alex Ozdemir, Hedley Rainnie, Rick Schieve,
     Gregg Woodcock.



The authors hereby grant permission to reproduce and distribute this
document for personal use, subject to the condition that the document
(along with any copyright and disclaimer notices) is not modified in any
way. The opinions expressed within this document are those of the authors
only and not necessarily those of the authors' employer(s). This document
is provided for informational purposes only. Although the authors have made
every effort to provide accurate information, they cannot guarantee the
accuracy or usefulness of any of the information contained herein due to
the complexity of the issues involved. The authors take no responsibility
for anything arising as a result of anyone using the information provided
in this document, and the reader hereby absolves the authors of any and all
liability arising from any activities resulting from the use of any
information contained herein.



Arcade video games are surprisingly simple beasts. They use power, control
panel inputs, and coins (lots of coins!) to display pictures on a monitor.
When you play a video game, you're interacting with a dedicated computer
built to play the game in question. Conversion is merely the process of
changing the computer inside the box to play something else.

Sometimes, all you have to do is change the software. Stored on EPROMs,
software changes can be as simple as swapping a single chip. A chip swap
like this, for instance, will upgrade a TMNT (Teenage Mutant Ninja Turtles)
board to play Turtles In Time. Often, however, things are more complex, and
may require different power supplies, new control panels, wiring work, and
more. Although monitors are normally never swapped from game to game, they
may also have to be rotated through 90 degrees, or have their input signals
manipulated. The "right" approach to any given conversion varies depending
on the games in question and the resources you have available.

Resources come in many forms, but the most important resources are money,
time, parts, and knowledge. Money is a useful resource, and is most
commonly used to acquire parts. Time is spent, both in finding parts and in
bending them to fit the task at hand. Parts are probably the most
fundamental resource, as they're the building blocks of your conversion.
Some parts are rare and require long, expensive searches. Other parts are
cheap and commonly available, but require a few hours of work before they
can be made into the games you want. Tony Jones is maintaining a list of
parts suppliers; see reference {9.3.1} for details.

Knowledge is the last piece; it enables you to combine the three other
resources into the games you want. Getting a hold of this FAQ is a good
first step towards acquiring that knowledge; trying some conversions will
be the next step. Old video game manuals are extremely useful, but are
increasingly difficult to find. And of course, there's always r.g.v.a.c. if
all else fails :-)

The types of resources available vary from place to place. If you've got a
warehouse next door where you can buy any game for $10, you'll be doing
conversions that minimize time and assume that you have a complete copy of
all the parts you'll need. If the nearest warehouse were 500 miles away,
you'll be either spending a small fortune to have a few precious parts
shipped to you, or you'll be building a lot of goodies from scratch.

Finding what you need, even if you're close to a warehouse, can be
difficult. Some parts are valuable, even though the games in which they
were used were total failures in the arcade, because they're Just Plain
Rare; while demand for such parts is limited, supply is even tighter. While
bulk buys of boards are often a good way of getting parts, nothing is

What we're trying to emphasize here is that no one approach is
intrinsically better than another. Often, an approach which makes sense for
your situation won't make sense when applied to someone else's. There will
even be times when an approach that made sense to you at one time won't
make sense to you today.

We've neglected to mention one other resource -- space. While space has
nothing to do with the feasibility of a given conversion, it's probably the
most important resource a video game collector has, as it limits the number
of cabinets he/she can install. As such, folks with lots of space may be
able to build up substantial collections without conversions. Those of us
who live in the real world, however, aren't usually so lucky -- space is
valuable, and saving space is what conversions are all about.

Hence this FAQ. Still, don't expect it to give you the "universal" approach
that allows you to play any game in any cabinet, because, as demonstrated
in our earlier discussion about resources, no such approach exists.

What you *can* expect from this FAQ, however, is a set of descriptions
about many different approaches to the task of conversion and some attempts
to explain what conditions suggest a given approach. Again, these
"conditions" are only guidelines. In the real world (especially when you do
your first conversion), things won't be as easy as they seem after reading
this FAQ, but at least you'll have been exposed to the various approaches
out there. With luck, you'll at least be able to think about which approach
might be right for you and your task at hand.


Anatomy of a Video Game

Since games are what it's all about, let's take a typical video game and
slice it up into its principal components:

  1. Monitor
        o That TV-like thing that displays the pretty pictures. Monitors
          come in two flavors: Vector and raster.
        o Vector monitors display straight lines using the same principles
          used by oscilloscopes; an electron beam is deflected from one
          point to another, leaving a line between the two points.
          Consequently, these are also known as "X-Y" monitors. These are
          becoming increasingly rare, as the last vector game was made in
          1985, almost a decade before this FAQ was written.
        o Raster monitors are more like televisions, in that the electron
          beam scans over horizontal rows of pixels, illuminating varying
          levels of red, green, and blue (RGB) phosphors. Raster monitors
          are the only type of monitor still in production for video games.
        o Vector monitors are *not* interchangeable with raster monitors.
          If you want to run Tempest in your Arkanoid cabinet without
          buying a new monitor, forget it.
        o Laserdisc games use raster monitors. These games use normal RGB
          montiors, but have additional circuitry to convert the NTSC
          output of the laserdisc to the RGB input that the monitor
  2. Controls
        o All controls perform the same function: conveying your actions to
          the game board.
        o There are many kinds of controls. Basic buttons, basic joysticks
          (digital, with switches, or analog, with potentiometers), encoder
          wheels (those funky spinning knobs, also common in driving
          games), trakballs, and more exotic critters such as Hall Effect
          joysticks, optical joysticks, funky light-detecting guns,
          force-feedback mechanisms (like in Hard Drivin') and lots of
          other things which are beyond the scope of this FAQ.
        o Coin doors are glorified buttons. There's some extra mechanical
          magic that allows them to differentiate between quarters and
          other coins, but you can treat them as pushbutton switches for
          the purposes of this discussion.
        o Games with *really* odd controls, like Discs of Tron's encoder
          wheel (which can be pushed in and out as well as rotated), or the
          eight-position rotating knobs from Ikari Warriors, tend to be
          very difficult to convert. It's often best to make sure that such
          specialized hardware comes with the boards.
        o Still, people *have* managed to do workarounds for weird
          controller schemes. The optical and hall effect sticks, (used in
          Sinistar and I, Robot respectively) have reportedly been
          obsoleted via such means. Reference {9.2.1} describes the hack
          for Sinistar.
  3. Speakers
        o Okay, so there's not much high-tech about speakers. You stick
          some signal into one end, and sound comes out the other end. The
          reason we mention them here is because the signal that comes off
          the board comes in two flavors: amplified and unamplified.
        o Amplified signals are the easiest to deal with. Stick 'em onto
          your speakers and enjoy the sound.
        o Unamplified output is a little tricker; it needs to be amplified
          before you'll hear anything. On an original game with unamplified
          sound (including most older Atari games, Universal's "Mr. Do"
          series of games, and many older Midway games), there was an audio
          amplification board somewhere in the cabinet that served this
          purpose. Odds are that you didn't get it when you got the game
          board, though, so you might have to build your own instead.
        o If you're going to try and run both types of audio in the same
          cabinet, you'll have to pay special attention to this issue,
          usually by putting an amplifier between the board and the
          speakers, activated when required by an external switch.
        o You can make a quick-n-dirty audio amplifier with an LM380 op-amp
          as follows: Put unamplified audio on one side of a 10K volume pot
          and the other side of the pot to GND. The center tap of the pot
          is connected to pin 2 (the input) of the LM380. Pins 7 and 3 of
          the LM380 go to GND. Connect pin 14 of the LM380 to +12V DC.
          (Don't forget an 0.1 uF decoupling capacitor between +12V DC and
          GND). Pin 8 of the LM380 (the output) gets a 2.7 ohm resistor in
          series with an 0.1uf cap to GND to prevent the chip from
          oscillating. Finally, stick the positive end of a 250 uF
          electrolytic capacitor to pin 8; the negative end of this
          capacitor goes to one of the speaker leads. The other speaker
          lead goes to GND. Power it up, and away you go!
  4. Power supplies
        o Turns ugly 120V AC power into nice, clean DC voltages usable by
          the board's electronic components.
        o Linear power supplies have large, heavy transformers and produce
          voltages which must still be regulated by other circuitry,
          usually located on separate pieces of hardware within the
          cabinet, and in rare instances, on the game board itself.
        o Switching power supplies are much lighter, cheaper, and easier to
          work with.
        o If you've got a vector game which needs a bunch of exotic
          voltages, you may not be able to find a switching power supply
          which suits your needs. You'll have to hunt around until you find
          the original (linear) power supply that was used with the game.
        o Some boards require only +5V and GND. Most require +5V, +12V, and
          GND. Older Williams machines may also require -12V. Other games
          require bizarre AC voltages, or high voltages like +25V. The
          stranger the power requirements, the more work you'll have to do
          to get things running without resorting to the game's original
          power supply. Vector games tend to have the strangest power
          requirements owing to the nature of their output circuitry; the
          vast majority of raster games can be run on +-5V and +-12V. You
          may not get all the features your game had (like
          electronically-erasable EPROMs to save the high score table), but
          you should be able to at least play the game.
        o "Normal" switching supplies are easily replaced; a standard IBM
          PC power supply will give you everything you need to power up
          most boards. Many collectors will replace an old linear power
          supply with an arrangement like this (or with a regular game
          switching power supply for $30 or so) in order to save themselves
          trouble down the road.
        o Linear supplies are much more difficult and are usually specific
          to one manufacturer and/or time period. Even then, it's easy to
          make mistakes -- the transformer associated with the linear power
          supply used by Atari's B/W vector games and some of their raster
          games is *NOT* compatible with the one used by their color vector
  5. Boards
        o The brains of the operation. Contains all the circuitry required
          to eat the power and your control inputs, and spew the results
          out to the monitor and speakers.
  6. Wiring harness
        o The glue of the operation. A set of wires that connects the
          preceding four chunks of hardware together. Not as simple as you
          might think, because gluing all these parts together requires
          connectors, and the required connectors are almost *always*
          difficult to find locally, and can also be expensive. If you
          don't have any luck locally, you'll have to find a good
          mail-order place and do your shopping the hard way :-)
        o If you *do* manage to find a source for connectors, on the other
          hand, building a wiring harness by hand, while time- consuming,
          is a fairly simple operation. This is a Good Thing, because
          original harnesses for older games are practically nonexistent.
  7. Cabinet
        o The wooden housing into which all of the above get crammed to
          create a video game. Heavy, bulky, and generally a pain to lug
          around. On the other hand, often beautifully decorated, and
          definitely something to take good care of if you've got one in
          good shape...
        o You *can* make a cabinet yourself, but it takes a lot of work.
          And a lot of time. And a lot of wood. And a lot of skill. And a
          lot of money. Minor restoration is tough enough; building a
          cabinet from scratch isn't recommended unless you have truly
          nightmarish space problems that would prohibit you from bringing
          in any form of "real" cabinet.
  8. Miscellaneous/specialized/custom/unique hardware
        o Spherical mirrors that reflect the image up (e.g. Time Traveler)
        o Video conversion equipment: Overseas folks may not have
          NTSC-compatible hardware. If a game puts out NTSC, it may have to
          be converted further to another format such as PAL or SECAM in
          order to be of use. Information on PAL, SECAM, and other video
          formats is beyond the scope of this FAQ; interested readers are
          encouraged to consult the newsgroup "rec.video" for further
        o Laserdisc equipment: Not only the discs themselves but the
          players and the NTSC->RGB conversion boards which convert the
          laserdisc player's output (a NTSC signal, such as that used by a
          television set) to the RGB signal (used by the monitor).
        o A recent development in arcades is the use of projection TVs.
          These are also raster displays, but they use an NTSC signal, as
          opposed to the more common RGB signal set. There's a small board
          inside such games which converts RGB to NTSC.
        o Keyboards (Thayer's Quest, Space War)
        o Joysticks with spinning knobs on the ends (Ikari Warriors)


Conversion Classes / Hardware Families

We just finished telling you that you couldn't put all the video games in
the world into one cabinet. And we meant it... well, sort of. If you plan
your purchases carefully, you can still get a lot of games in a fairly
small number of cabinets.

The key is to divide the games into families of similar age, manufacturer,
and display hardware. Consider the following sample "conversion classes";
the list below is by no means exhaustive, but should give you an idea of
how various games are grouped.

The "conversion classes" are grouped into two sections, vector and raster.
These refer to the type of display used by the games in question. Each
vector class is further grouped around the display technologies used by the
respective manufacturers. Although each manufacturer and display technology
is different, the hardware driving any particular manufacturer's technology
is similar, leading to a set of fairly easy conversions.

For example, Cinematronics used essentially the same hardware (with very
minor modifications) for all of its B/W vector games from 1977 (Space Wars)
until 1981 (Solar Quest). All in all, they produced over 10 games using the
same bit-sliced architecture, even though microprocessor-based vector games
had been around since 1979 (when Atari introduced Lunar Lander).

Even when the hardware changes, the display technologies remain the same.
Despite many changes in design of monitor and hardware, all of Atari's B/W
vector monitors remained interchangeable, and so were all of their color
vector monitors. While two of their games (Tempest and Quantum) mounted the
monitors vertically, the monitors were identical with those used in their
previous games.

For the more common raster arcade games, each class is only centered around
similar hardware, as the display technology has remained static over time.
Physical orientation (horizontal/vertical) of the monitor, sync type
(composite/separate), and sync/color polarity (positive/negative) may vary,
but these can all be compensated for with external circuitry.

Most hardware platforms were similar only for a few years at the longest,
so you'll notice that the raster games listed in a particular year also
were made about the same time. After a few years (or in some cases, a few
months), larger memory chips, faster processors and other hardware could
reduce costs and allow bigger, fancier and more complex games to be
developed for the same price, and the manufacturer developed new hardware
to match the new technology. The "new/old Williams" series of games are
prime examples of technological evolution in action.

In modern times, everything has been standardized so that conversion
classes are based on pinouts, not game hardware. The JAMMA standard and the
earlier Konami standard are examples of this; these conversion classes
exist because manufacturers agreed to use the same pinouts, regardless of
the (often radical) changes in hardware design from game to game.

The advantage of breaking games down into conversion classes is that it
gives you an easy way of evaluating whether or not a given board is
immediately useful to you, or whether you'll have to do substantial work to
get things running. Someone with an Atari color vector game at home can go
into any operator's warehouse and *know* that they should be able to use
(or at least test), fairly easily, any Atari color vector boards they may
happen to find, but that the (Sega) Space Fury set in the nearby pile may
require a lot of work. If they only have enough money or time to pick up
one pile of boards, the Atari color vector pile is definitely the one to go
for. No need to waste the operator's time asking "gee, can I plug this into
my Gravitar machine at home?", just an internal mental note of "yup, I can
use this easily", or "nope, I haven't a *clue* what to do with this one".

It also gives you the advantage of knowing what's easy to trade. Even if
you don't have the equipment required to run (or even *test*) the Atari
vector games in the hypothetical pile above, you can know that someone out
there will. If you've got the cash, and the pile is there, just grab it and
trade with other collectors to get boards you *can* use.

Vector game conversion classes:

Atari Color Vector
     Gravitar, Space Duel, Black Widow, and possibly Quantum
     Major Havoc, Tempest
     Star Wars, Empire Strikes Back
Atari B/W Vector
     Asteroids, Asteroids Deluxe, Lunar Lander
     Battlezone, Red Baron
Cinematronics BW Vector
     Rip Off, Star Castle, Armor Attack, Solar Quest
Sega Color Vector
     Space Fury, Eliminator, Star Trek, Tac Scan, Zektor

Raster game conversion classes:

     Centipede, Millipede, Xevious, Dig Dug, etc...
     Mad Planets, Reactor, Q*bert
     Galaga, Bosconians, Mappy
     Tron, Discs of Tron
     Mario Brothers, Donkey Kong, DK Jr., DK III, Popeye, etc...
     Pacman, Ms. Pacman, Pacman Jr., Pacland, Galaxian, but (hey, there's
     always one exception :-) *not* Super Pacman.
old Williams
     Robotron, Joust, Stargate, Defender, Sinistar, Bubbles
new Williams
     Blaster, Joust II, Mystic Marathon, Inferno
Laserdisc games
     Dragon's Lair, Space Ace, Thayer's Quest, Super Don Quixote
Konami standard wiring harness
     Time Pilot, Super Cobra, Scramble, Frogger, Gyruss, and many more.
JAMMA standard wiring harness
     Many games now use the JAMMA pinout standard. Getting a JAMMA cabinet
     will make the rest of your collecting life much easier. Since JAMMA is
     newer, more common, and (most importantly) has *more pins* than the
     Konami connector, it's generally easier to work with. Besides, you can
     always build an adaptor to play Konami games in a JAMMA cabinet.
     (Adaptor, you say? Playing games in other cabinets? Hey, sounds like a
     conversion! We'll be seeing more of this later...)

Using conversion classes to have it ALL:

Getting back to the issue of conversion and your arcade video game
collection, we'll use the above conversion classes and a sample game
collection to try and "cover" all your favorite games.

Suppose you'd like to have the following 12 popular games:
- Tempest, Battlezone, Asteroids, Star Wars, Joust, Space Duel, Stargate,
Gravitar, Defender, Robotron, Star Castle, Sinistar

Robotron is in the "old Williams" conversion class; it'll make a nice home
for Joust, Stargate, and Defender. Stargate will require a new control
panel, Sinistar will require a fair bit of work, but might also be done if
you can find the parts, and Defender has a unique board set, but you could
probably work something out without much difficulty, as it will plug
directly into a Stargate harness.

Space Duel is in the Atari color vector conversion class, which covers
Gravitar, Tempest, Major Havoc, and possibly Star Wars (although Star Wars,
Major Havoc, and Tempest will need the proper controls...)

Rip Off is in the Cinematronics B/W conversion class, which gives you Star

Finally, Asteroids Deluxe provides a home for Asteroids and Battlezone
(although again, you'll have to worry about the Battlezone control panel).

Not bad. 3 manufacturers, 4 cabinets, 14 games. We'll see later that the
Asteroids<->Asteroid Deluxe conversion, the Rip Off<->Star Castle
conversion, the Joust<->Robotron conversion and the Space Duel<->Gravitar
are extremely easy due to the similarity of controls and hardware. At any
rate, we've covered a large proportion of the most popular classics, and we
did it by starting with four commonly-available (and thus less expensive)
games, namely Rip Off, Space Duel, Robotron and the extra Asteroids Deluxe.

Indeed, you can get more games out of these cabinets, including Bubbles,
Black Widow, Major Havoc, Red Baron, Armor Attack, and Solar Quest, so you
really have 20 games in your four cabinets. Not bad for a day's work. Even
if you don't particularly care for all of these games now (and indeed, you
may not have even *heard* of them!), you might feel like adding them to
your collection in the future, just to try them out. Conversion gives you
the flexibility to do this without having to carry home another six
cabinets (on top of the 14 you'd have already purchased if you were trying
to do this without conversions) for these relatively obscure games, "just
to see if you like 'em". You can also buy the boards or other hardware for
each new game separately for far less than the cost of a full-sized

For bonus points, use some of the space you've saved so far to buy two
JAMMA cabinets, one with a vertically-oriented monitor and one with a
horizontally-oriented monitor. You now have the potential of doing
conversions for your older raster games to JAMMA (of course, if you enjoy
newer games, they may already *be* JAMMA!), and being able to add literally
hundreds of games to your collection without taking up any more space
whatsoever. Every bulk buy you do should net you several games you can
convert to JAMMA, which can drastically expand the size of your arcade at
minimal (financial and space-wise) cost.

If you can't appreciate reducing the space (and cost!) that your ideal
arcade takes up by a factor of three, then you're either rich, single, live
in a *BIG* house, or all three. Put another way, just discuss the matter of
putting a dozen full-size arcade games in your parents' garage or
significant other's apartment and you'll soon realize that conversions save
more than just space!


Conversion Theory

As we mentioned before, several approaches exist to doing a conversion.
Each approach has advantages and disadvantages, including ease of
construction, cost of parts, and space occupied. We'll discuss four of the
most popular approaches here:

Plug-n-chug: Swap motherboards. No homebrewed hardware, soldering time, or
brains required, and thus much favored by operators :-). The JAMMA standard
is based on this philosophy.

Control panels: Sometimes you'll have to hack on the control panel, or even
make an outright swap of old one for a new one. Not really a conversion per
se, but we include it here because it's a very common technique that is
often required when doing conversions of any type.

Adaptor-hackery: Swap motherboards, but stick an adaptor between the new
board and the old harness. If edge connectors are easily available in your
area, this approach can be both cheap and relatively quick. This approach
is very commonly seen in collector circles, but due to the time required to
creating the adaptor in the first place, its use among operators was
limited, even in the days before JAMMA.

Banking, or EPROM-hackery: EPROMs, Rube Goldberg-like adaptors sitting on
motherboards, and the sweet scent of solder. Run two (or more) games off
the same motherboard with the flick of a switch. Time-consuming to build,
and requires a bit of electronics experience. Never used by operators for
these reasons (plus the fact that operators don't need to switch games
frequently -- it's easier for them to just swap boards and maybe insert an
adaptor every few weeks when earnings drop...), but very useful for
collectors who have a hard time finding video game parts.

All-in-one: Putting the guts of more than one game in one cabinet. Like
other conversions, it saves space and time, but requires a lot of manual
labor. This approach is never used by operators (who merely wheel in a new
board or machine when it's time to switch), but can be useful for a
collector with a roomy cabinet and two (or more) complete wiring harnesses
on hand. This is a relatively rare situation; if you have to construct the
wiring harness yourself, you're probably better off using one of the other

"Plug-n-chug", or "Board-swapping":

This is the simplest type of conversion. You simply power off the machine,
disconnect the board set, and insert a new board set. Powering up the
machine completes the conversion; you've got a brand-new game.

Sadly, not every conversion is going to be this easy. You can't do this at
all unless the pinouts for the boards are identical, which is often not the
case, even for fairly recent games. And it's almost *never* the case for
older games.

The JAMMA (Japanese Arcade Machine Manufacturer's Association) pinout
standard (a 56-pin connector) was developed in an attempt to rectify this
situation; by providing a standard pinout, any JAMMA board can be plugged
into a cabinet with a JAMMA wiring harness.

Earlier attempts at standardization included the Konami wiring standard
(early 1980s, using a 36-pin connector), the Universal wiring standard (the
entire Mr. Do! series of games, Ladybug, and a few others used a 56-pin
connector, but one that is *NOT* compatible with JAMMA), and the Sega
wiring standard (mid-1980s, also using a 56-pin connector, and *ALSO*
incompatible with JAMMA). Some early Capcom games also fit this pattern -
56 pins, but not JAMMA.

The point we're making here is that while most recent games are built to
the JAMMA standard, other standards *do* exist, and you should be aware of
them. Under no circumstances should you assume that a board with a 56-pin
connector is automatically JAMMA, unless you've looked very closely at it

Some manufacturers make it easy for you - printing the word "JAMMA"
directly onto the PCB. Others don't. Your best bet is to get the pinouts
for the various standards (Reference {9.3.2} (the wiretap.spies.com FTP
site) is the best place to find them online), and compare them with your
board. If you get a match with any of them, you'll either be able to play
it in your harness, or construct an adaptor to fix the problem. Adaptors
will be discussed in the next section.

Hacking or swapping control panels:

So you've just compared two sets of pinouts and seen that they're basically
the same. You plug the new board in, power things up, and everything works
fine until you try and start a game. You then remember that the controls
are different.

Bummer, eh?

Well, not really. 90% of the work has already been done; the game is up and
running, so the rest is just a matter of wiring.

As an example, we'll take Gravitar and Space Duel. These boards have
identical pinouts for power, sound, and video, so you can just
"plug-n-chug" to power things up. As the control panel portions of the
games' pinouts differ, you've still got a little more work to do before
you've finished the conversion.

(In case you're wondering why the panels were made incompatible, Atari
didn't want to make it too easy for operators to have their cabinets
playing different games -- this was before JAMMA, back in the
Golde^H^H^H^H^HDark Ages when each game came in its own cabinet, with its
own artwork, marquee, and control panel.)

What this means is that if you're trying to put a Gravitar board in a Space
Duel cabinet, you'll need to rewire it using a switch with six poles -- to
swap the six signals going to the panel, depending on which game you're
playing. The end result should look something like this:

PCB    Space Duel controls      Corresponding button on Space
pin    wiring harness pin       Duel panel for SD or Gravitar
                          _________P2 Rot R (for playing SD)
19-E_______Pin 3_________/
                         \_________P1 Rot L (for playing Grav)

                          _________P2 Thrust (for playing SD)
20-M_______Pin 4_________/
                         \_________Select Sw (for playing Grav)

                          _________P2 Fire (for playing SD)
19-4_______Pin 5_________/
                         \_________P1 Fire (for playing Grav)

                          _________Select Sw (for playing SD)
20-11______Pin 7_________/
                         \_________Start Sw (for playing Grav)

                          _________P1 Fire (for playing SD)
19-3_______Pin 11________/
                         \_________P1 Shields (for playing Grav)

                          _________Start SW (for playing SD)
19-6_______Pin 14________/
                         \_________P1 Thrust (for playing Grav)

The rest of the control panel inputs don't matter since they are either the
same (i.e. both games use the same PCB pin for the button/game function) or
left unused by Gravitar.

The other option, if you don't have a six-pole switch handy, but you *do*
have a Gravitar control panel handy (remember we talked about "resources"
earlier?) is to simply swap panels. Rig up an adaptor to go between the
Gravitar control panel and the rest of the Space Duel wiring harness. As
you're only interested in the control panel inputs, this can often be a
convenient "shortcut" around the adaptor hackery route which we'll be
discussing next.

This was all about adding a Gravitar board to a Space Duel cabinet. Going
the other way with a simple control panel swap is much more difficult,
owing to the larger number of inputs required by Space Duel. These
difficulties will be discussed in more detail in the next section.


For all practical purposes, hacking or swapping control panels is really
just a sidetrack from the types of conversions available; it's something
done to facilitate a conversion, rather than being a conversion in and of
itself. At the end of our discussion on control panel hackery, we mentioned
that one could construct an adaptor that would go between the new control
panel and the old wiring harness. Since you have to swap both the board
*and* the control panel, and since these two parts are normally located
fairly far away from each other in most cabinets, why not move the adaptor
to the other end of the wiring harness? There are times when it's much
easier to simply place the adaptor with the new board itself.

Such adaptors are the next-simplest form of conversion. They're what you
usually build when your new board doesn't match the wiring harness of the
game you're trying to play it in. They take a little time and effort to
build, but are almost always worth it. Experienced collectors will often
accumulate large "libraries" of adaptors to use with their games.

To build an adaptor, you'll need accurate pinouts for both your wiring
harness and for the board set(s) you're trying to plug into it. Of course,
if the pinouts match, you've got a "plug-n-chug" situation, and no adaptor
is required.

If not, however, you might consider modifying the board to suit the
harness. This is generally a *bad* idea; you'd like to keep the board as
intact as possible, if for no other reason than you'd like to be able to
trade it with a friend someday, or send it off somewhere to have it fixed.
Moreover, cutting leads and soldering wires directly to a board may also
damage it, create unreliable solder connections, and may also make
debugging your work more difficult. On the other hand, adaptors require
parts, and if you're *really* desperate for parts, you may have no choice
but to modify the board directly, even if you may regret it later.

Rather than modify the board directly, most people build an adaptor to
stick on the end of the board. This is a little device composed of some
connectors and wire, and it maps the board's pinout to that of the wiring

To construct an adaptor, look at your wiring harness, the old board that
lived there, and the new board you wish to plug into it. What you want to
do is create something that will make your new board "look like" the old
board (from the perspective of the old wiring harness), and your old wiring
harness "look like" the new board's harness (from the perspective of the
new board).

For instance, if your old board (and thus, old wiring harness) used the
JAMMA standard, you'd want your adaptor to have a 56-pin male edge
connector on one side. The combination of "new_board+adaptor" should look
like any other JAMMA board. If your new board were, say, a Dig Dug board
with a 44-pin male connector, you'd want the adaptor to have a 44-pin
female edge connector on the other side. The combination of
"old_harness+adaptor" should match Dig Dug's pinout.

Between the two sides of the adaptor, you'd have a set of wires, carrying
the JAMMA harness's +5V to the proper pins of the Dig Dug female edge
connector, and the Dig Dug video output pins to the proper pins of the
JAMMA harness.

The end result would look something like this:

        --------< <-----------> >--------~~~~~\/~~~~~~~~~~------<
TO      --------< <-----------> >--------~~~~~'\/~~~~~~~~~------< DIG
JAMMA   --------< <-----------> >--------~~~~~~'\/~~~~~~~~------< DUG
WIRING  --------< <-----------> >--------~~~~~~~'`~~~~~~~~------< PCB
HARNESS --------< <-----------> >--------       /~~~~~~~~~------<
        --------< <-----------> >--------~~~~~~'
        56-pin      male-male   56-pin     Wires that map  44-pin
        female      PCB with    female     JAMMA pinouts   female
        edge        straight    edge       to 44-pin Dig   edge
        connector   traces      connector  Dug pinout.     connector

In this simpler case (where the pinouts from the new game are a subset of
the older game's pinouts), you can just ignore the "extra" pins on the
wiring harness. Dig Dug only had one fire button, so you don't need to hook
up anything for the JAMMA standard's other two buttons.

On the other hand, if your wiring harness is for the board with the smaller
number of pinouts, then you may have to enhance the wiring harness to take
into account the "extra" leads for the new game. The JAMMA standard has
enough pins for most games on the market, both old and new, and thereby
avoids this problem; this is another reason for its popularity. Even if you
can swap control panels easily, putting an SFII board set into a Dig Dug
cabinet is going to require some modification of the Dig Dug wiring harness
to carry the extra button signals to the control panel.

The point of all this is that no adaptor can make up for the fact that your
new game may want three more buttons than your old cabinet supported. At
least, not unless you feel like drilling holes in your nice, clean control
panel and making extensive wiring harness modifications. As such, adaptor-
hacking approach is best used for cabinets with *lots* of buttons or
sticks. Games like Rip Off, Space Duel, and SFII have tons of buttons to
play with; it isn't a coincidence that we suggested two of these three
cabinets earlier in this FAQ. As of this writing (October 1994), the price
of SFII games has dropped dramatically over the past six months, so you may
want' to consider an SFII cabinet for your horizontal JAMMA machine.

At any rate, if you have the choice, work from a JAMMA cabinet. If you
can't find a JAMMA cabinet in the right price range, you could also
consider getting a non-JAMMA cabinet, removing the original wiring harness,
and putting a JAMMA harness.

Similarly, if you're going after Atari vector games, go for a Space Duel
cabinet if you can find one. It's got *LOTS* of pins on its wiring harness,
and should be able to handle any other Atari vector game you decide to
throw at it.

One final note: the adaptor-construction approach requires parts that
you're not likely to find at your local Radio Shack (edge connectors,
male-male PCB pieces, etc...). Unless you live near a really good
electronics store, or an operator's warehouse, you'll probably have to
mail-order some stuff in. On the other hand, at least the parts required
aren't unique to any particular game, so you can pick up a big pile of
parts at once and never have to worry again.

See section {8.5} for some alternative methods of adaptor construction.

See reference {9.1.1} for an example of this kind of hackery as applied to
Asteroids and Asteroids Deluxe.

See reference {9.1.2}, (Space Duel -> Gravitar), for more details on how to
modify a Gravitar board to put it into a Space Duel wiring harness and an
example of this technique.

Finally, adaptors don't have to deal with edge connectors only. See
reference {9.1.3} (Joust -> JAMMA) for a series of adaptors that will allow
you to convert the complicated board set for Joust (and by extension, other
Williams games) to JAMMA. This hack also involves the inversion of the
game's sync polarity, which is explained in more detail in section {8.6.3}
of this document.

"Banking", or "EPROM-hackery":

This approach requires a complete understanding of the hardware
architecture of the similar games AND how the hardware addressing works so
you can use a larger EPROM to hold multiple games.

Because this type of conversion requires detailed technical knowledge, it
probably isn't appropriate for a beginner who has no help. On the other
hand, a beginner with the schematics of the games in question and a little
electronics knowledge, plus a document describing other hacks of this
nature (say, this FAQ), would have a fighting chance. Knowledge is the key
- if you've got enough background information and you think you can get it
to work, then you probably *CAN* get it to work, so by all means, go ahead!

Anyways, with "banking" you'll put the code for different games in
different sections of a large EPROM, where each section serves as a bank of
memory. To select the different banks of larger EPROMs, you'll run a wire
to a switch that hardcodes the EPROM's upper address lines to particular
values that point to the section of the EPROM corresponding to a given
game, and if you have spare positions on the switch you can handle any
control panel discrepancies with the switch. Unfortunately, any differences
in peripheral boards (like sound boards), memory size, or interrupts are
going to be more difficult to handle, since these are differences in the
motherboard architecture will hinder the sharability of the motherboard
between various game's code.

If you have extra poles on your switch, you can select the use of different
hardware or modify things like interrupt handling. If the total length size
of the games' code differs, you can avoid have addressing problems, in
cases where the sizes of the game code are multiples of a power of two --
place multiple copies of the smaller game's code until you fill a bank
equal to the size of the larger game's code. This way, the contents of the
upper address lines won't be noticed when the smaller game is playing. The
idea behind these types of conversions is that "cheap hacks" are the order
of the day. Silicon is cheap these days, but wire is still a pain to wrap,
so don't be shy about using lots of EPROM space if it'll simplify the

See reference {9.1.4} (Cinematronics conversions) for more details on how a
Cinematronics motherboard can be modified to use larger EPROMs that hold
several games from that manufacturer. Note that in this case the sound
board which is unique to each game presents a problem that can only be
overcome by allocating a *LOT* of poles on the switch!

Also, references {9.1.5}, {9.1.6} and {9.1.7} contain examples of this
technique as applied to Gravitar and Black Widow, and four older Williams
games (Robotron, Joust, Stargate, and an upgraded hack for Bubbles).

One last word on EPROM-hackery. Many games use similar hardware
architectures, but protect themselves through the use of custom security
chips. Everything from basic PALs and GALs through to some truly exotic
beasts have been used. On such games, an EPROM swap will *not* work, no
matter how "clean" it may look on paper, because the game depends on the
existence of the custom chip to work properly. There's not much you can do
under these circumstances; security chips are designed to be unique to a
particular game, and are also designed to be extremely difficult to
reverse-engineer. While "difficult" does not always imply "impossible", it
suffices to say that if you know how to defeat such schemes, you don't need
to be reading this FAQ, as you're several miles above the rest of us mere
mortals. (Might we suggest the FAQ for misc.legal instead? :-)

"All-in-one", or "Transplanting":

This approach requires a substantial amount of hardware (power supply, new
board set, and all auxiliary board and wiring harnesses) and a roomy
cabinet to boot, since you're basically transplanting the innards of your
new game into another game's cabinet. As you might expect, internal space
constraints do tend to limit the number of games you can put into a single
cabinet using the "All in one" approach.

This approach centers around combining the video signals coming from
several boards at the monitor. Usually, a switch controls which board gets
power, and this board will provide the signal to the monitor. If all your
boards have the same power requirements, then the power supply can also be
shared; you'll switch power to each board individually instead of switching
on one of many power supplies.

In the case where the video signals are digital (e.g. the Cinematronics
vector games) you only need to feed the inputs from several boards through
a multi-input AND gate that has pull-up resistors everywhere. In the analog
case (which includes most raster games and other vector games), things are
more difficult, since you want to send output from the running board to the
monitor, while at the same time disconnecting the powered-off boards from
the circuit. Switches come in handy here, but the wiring can still be

A transplanted system is a lot of work to set up. While a single switch can
divert power and video from one set of boards to the other, it takes a lot
of hardware and time to create such a setup.

If you've already got the hardware, it's not too bad, but you should also
be warned that this method is fairly permanent; once you hack the two (or
more!) games into the cabinet, you'll have very little room to work inside,
and because of the serious wiring modifications you may have done, you'll
be likely to hesitate before changing anything else.

An example of someone who might consider this approach would be someone who
just inherited an empty Tempest cabinet that was in horrible physical
condition, with deep scratches on the cabinet, water damage, etc., but was
otherwise (i.e. electronically) sound. The wiring harness and power supply
could be salvaged and transplanted into a Gravitar, Black Widow, or Space
Duel cabinet, and they'd get a spare color vector monitor as a bonus.


Conversion Examples

Below are some descriptions of some of the easier conversions. These
descriptions aren't supposed to contain every detail needed for the
conversion (hey, only the manual is supposed to have all that detail, and
besides, FAQ space is limited, just like in your basement!), but they'll
give you a general idea of what you'll be doing.

Once you've read through a conversion that can be described in a paragraph
or two, we are hoping you'll be tempted to go try it yourself (with the
help of the appendices and manuals of the games you intend to convert).
We've picked these as fairly simple examples in order to illustrate the
principles involved; consult the actual documents if you'd like to
understand more.

JAMMA: All JAMMA games <-> All other JAMMA games ("Plug-n-chug")

Swap boards and play. Tough, wasn't it?

The only catch is whether the game was designed with a
horizontally-oriented monitor in mind, or a vertically-oriented monitor.
Assuming the monitor is the same orientation for the new game in question,
you're done. (Unfortunately, no one has yet compiled a list of all vertical
and horizontal games that conform to the JAMMA standard, so it's a bit
tough to figure out whether it's JAMMA and what orientation the monitor
should be, just from the game's title...)

JAMMA doesn't always answer everything - sometimes game designers will
cheat, and sometimes JAMMA doesn't have enough pins. Four-player games
(Teenage Mutant Ninja Turtles), and multi-button games (SFII) are examples
of these situations. The boards are JAMMA, but you need to do a little
extra work to get things playable.

Cinematronics: Armor Attack <-> Rip Off ("Plug and chug")

Plugging and chugging isn't limited to new games. If the hardware was
suitably designed in the first place, you can do it with many older games
too. Suppose we already own an Armor Attack cabinet, but we went shopping
last weekend and picked up a Rip Off board set.

If you plug a Rip Off board set in place of an Armor Attack board set, you
can simply power up the Armor Attack cabinet and play Rip Off to your
hearts content. This is possible because both games use identical control
panel inputs. (Of course, you may find the Armor Attack screen overlay
rather obtrusive; if so, just remove it before playing Rip Off...)

You may have guessed that this conversion also goes both ways; you can also
put an Armor Attack board set into a Rip Off cabinet, though in this case
you may have to "guesstimate" the location of the colored sections of the
Armor Attack overlay.

See reference {9.1.4} for the full details on all Cinematronics

Cinematronics: Armor Attack <-> Rip Off ("Banking")

Okay, let's try that same conversion again, but let's assume that we didn't
get as lucky when we went shopping, and we don't have a complete board set
to work with. Instead, all we managed to find was the sound board.

It just so happens that the Armor Attack program is twice the size of the
Rip Off program, so to compensate we'll burn a 2732 with TWO copies of the
Rip Off program, making it the same size as your Armor Attack program. Now
the motherboard can choose an instruction from either copy of the Rip Off
program and it will find the correct instruction it needs to play Rip Off.

Again, because Armor Attack and Rip Off have identical control panels, no
changes to the control panel need to be done. The only hardware required is
a Rip Off sound board, swapped in place of the one for Armor Attack. (Okay,
so you have to flip the diagnostic DIP switch #7 to "ON" for Rip Off, but
who's counting?)

Note the main difference here -- instead of swapping whole board sets,
you're using the same Armor Attack motherboard in this conversion. This is
very handy if you're missing a spare copy of the motherboard in question.

See reference {9.1.4} for the full details on all Cinematronics

Cinematronics: Adding Star Castle ("Banking" / control panel mod)

Now, if you were to "double up" Star Castle the same way you did with Rip
Off, you'd have three games of the same size -- Armor Attack (your original
motherboard) and the two (doubled) games, Star Castle and Rip Off. Apart
from switching the test-mode DIP switch (#7) again (Rip Off expects it to
be ON; Star Castle and Armor Attack expect it to be OFF), there's nothing
stopping you from doing the same banking trick again and putting a third
game into your cabinet.

This time, you'll need to add some extra wiring to the control panel to
compensate for the differences. Hook up the P1 START button to #10 on the
control panel's patch panel (located under the control panel), the P1
THRUST button to #6, and P1 FIRE to #8 on the patch panel.

Grab a Star Castle sound board to go with the first two sound boards, and
swap away. Three games, one motherboard, one cabinet. (And if you're
wondering why Cinematronics didn't use copy-protection, the unique (and
almost impossible-to-reproduce) sound boards served the purpose quite well.
Unless you were willing to play without sound, the games were "protected"
from such copying.

See reference {9.1.4} for the full details on all Cinematronics

Williams: Robotron to Joust (More "Banking-and-control-panel-hackery")

Both games have identical hardware; only the ROMs change. If you've got the
other game's ROM board, you can "plug-and-chug" and be off to the races
(after you've hacked the control panel.)

On the other hand, if you don't have the other game's ROM board, you can
make do by just burning a new set of chips. In short, rather than swapping
boards, swap ROMs directly. Make sure that you use the same type of EPROM
(2532 or 2732) as the Robotron originally had. Burn a set of EPROMs with
the Joust ROM images and put them in the ROM board. Do the same thing for
the sound board's single EPROM, and hook up the control panel. Done.

A more sophisticated approach is to combine the EPROMs into one chip for
program ROM, and one for sound ROM. Swap two chips, not thirteen, when you
want to swap games. The full hack, along with information on getting
Stargate up and running, is documented in reference {9.1.6}. Reference
{9.1.7} takes it one step further and shows you how to get Bubbles out of
it by upgrading the motherboard.

The optimal approach is to use the hacks described, and "bank" all four
games onto one set of chips. This is left as an exercise for the reader.
It's not terribly hard to do, but you'll need an EPROM programmer capable
of handling very large (256K-by-8, or 2-megabit) EPROMs.

Atari: Asteroids and Asteroids Deluxe ("Adaptor-hack")

This is one of the simplest adaptors to create, especially given that we're
talking about an ancient pair of vector games.

Nevertheless, the pinouts between the two games are very similar. By
exchanging pins N with 12, P with 13, and S with 15, you're done.

Create an adaptor that connects all pins (except the pins to be swapped)
"straight through". If the edge connectors you've chosen for your adaptor
are feeling cooperative, you can do this without any wire at all, save that
used for the exchanged pins.

However you do it, once you've built (and checked) it, plug one end into
your Asteroids (or Asteroids Deluxe) board, and plug the other end into
your Asteroids Deluxe (or Asteroids) wiring harness, power things up, and

See reference {9.1.1} (Asteroids <-> Asteroids Deluxe) for the full
details. References {9.1.8} (Gravitar -> Tempest) and {9.1.9} (Gravitar ->
Major Havoc) contain examples of adaptor hacks applied to other games.


Debugging Tips

So, your conversion doesn't work. Bummer, and welcome to the club. This
section isn't intended to be a complete guide, but it should serve as a
useful checklist for your first stab at making things work. You should also
probably check the "Miscellaneous tips" section, as it's got some random
tidbits of information that may also prove useful as you try and understand
what went wrong.

   * Before you power up, check your wiring. Pay extremely close attention
     to your power and ground connections; checking them more than once is
     perfectly fine. On valuable boards, one of our authors has been known
     to check three times -- anything less than a unanimous "yes, it's
     perfect", and the power switch doesn't go on.

   * After you power up and it doesn't work, check your wiring. It's
     amazing how many times you can look at a piece of wire and say "yup,
     it's in the right place", and still be wrong.

     Trust us on this one.

   * Also check your wiring against "standard" documentation, and if that
     doesn't work, check it against the hardware itself.

     You may be doing everything "right" according to the document you
     found on the 'net, but a look at the schematics will highlight an
     error. This may come as a shock to some, but there have been real
     incidents in which stuff posted to USENET did, in fact, contain
     errors. Film at 11.

     Conversely, you may be developing a conversion from scratch, and
     you'll find errors in the official manufacturer's schematics. These
     are rare, but they're out there. If there's any doubt, check the
     hardware itself. Silicon doesn't lie.

     A word on manuals -- there's no "library" of manuals out there, nor
     will there be. Most manufacturers stop supplying manuals for their
     games after a few years (Atari is the lone exception; $14 will get you
     a copy of any manual they've ever made), so the only real sources of
     docs are whatever you can find when you're out buying, or the archives
     of other collectors on r.g.v.a.c. Playing librarian isn't a whole lot
     of fun, but a cheque for $20 or so will still convince most collectors
     (at least in 1994) to dig through their files and find a copier.
     Still, it does take time, so if you're working with Atari parts, we
     recommend you deal with them -- (while there's sometimes a risk that
     the schematics will be photo-reduced beyond the point of legibility,
     they've also been known to send original copies if they have a large
     enough inventory. Ya pays your money and ya takes your chances, but
     the service is still infinitely better than that offered by other

   * Regression-test. If you're at a stage where you think that part (even
     if not all) of the conversion will work, power it up and see what
     happens. If it works, you've at least got something you can go back
     to. For instance, when creating a JAMMA adaptor for a game, hook up
     power and video outputs -- this will tell you whether the game works
     or not. Once you've got this working, you can worry about sound output
     and control panel inputs.

     Be careful when regression-testing. If your adaptor doesn't work, and
     you suspect it may have damaged the board in the process, check the
     power supply before continuing. If the power supply is damaged, it may
     also damage any *new* boards you plug into it. The point here is to
     verify that *all* parts of your system are still in working order
     before continuing any further.

   * Go backwards. If things stop working, go back to the last point at
     which things worked, and see if you can't figure out where you might
     have goofed.

   * Check your assumptions. If you're doing a banking-style conversion and
     things work for one game (but not another), maybe you misread
     something on the schematics. Sometimes different games will use the
     same hardware in different ways; Robotron is an example of a game for
     which a simplistic address-decoding scheme will work fine, but the
     same scheme will fail on Joust and Stargate. The assumptions you make
     for one game may not hold true for others, even if the underlying
     hardware is practically identical. Diagnostic output from the game's
     self-test routines can be very useful here.


Miscellaneous Tips


     Buttons are generally grounded on one side, so that the PCB will see
     the input pulled low when the button is pressed.

Leaf switches and microswitches:
     There are two kinds of switches: leaf switches and micro- switches.
     For most applications, they're interchangeable. Leaf switches have no
     "clicking" sound when pressed and were common on old games; the newer
     microswitches make a definite "click" when pressed and are more common
     on newer games.

     Microswitches are more reliable than leaf switches, and also provide a
     "normally-closed" output (the inverse of the "normal" operation of a
     leaf switch or microswitch). This output can be put to use as
     described later.

     For normal applications, it doesn't make any difference which kind of
     switch you use. Some players prefer one over the other; it's this
     author's experience that one can develop a faster "touch" on a leaf
     switch (useful for something like Defender), but you lose something in
     terms of definitive feedback (which would be valuable on a game like
     Street Fighter).

Digital joysticks:
     Digital joysticks are the same as four buttons; instead of pressing
     buttons with your finger, you press them with the stick.

Analog joysticks:
     Analog joysticks are most often potentiometers and springs. The
     "flight yoke" controllers for Star Wars, Firefox, and STUN Runner, for
     instance, are all based on 5K pots. Other examples of this type are
     the analog "thrust control" for Lunar Lander and the steering wheel in
     Spy Hunter.

Optical joysticks:
     The funky "optical joystick" used by Sinistar is a piece of
     engineering artwork. It's also very rare, and even when it can be
     found, it's usually very expensive.

     It can also be replaced with a conventional (microswitch- based)
     joystick. Note that it must be a microswitch-based stick to work, as
     it relies on the use of the "normally- closed" outputs that only a
     microswitch can provide.

     See reference {9.2.1} for more information on Lee Crawford's Sinistar
     Joystick hack. At $8.00 and some wire, versus $130.00 and a few weeks'
     wait for mail-order, you might want to give it a try.

Hall-effect joysticks:
     These are exotic creatures. If you find any at a bulk buy, and you can
     get 'em cheap, go for it. They're generally very hard to come by, and
     can be expensive if you try to purchase directly from the

     John Lee writes:

     "The Hall Effect is a phenomenon in electronics where a static
     magnetic field causes a small electrical potential to be created in an
     electronic device. These devices are available commercially as "Hall
     Effect sensors" and are used as switches. They work very nicely in
     environments where things must be sealed, have less moving parts than
     other switches, and there aren't any electrical contacts to wear or
     oxidize--just move a magnet near to and away from the sensor to
     activate and deactivate it. Hall-effect keyboards can work just fine
     in very dusty, humid, or explosive environments, for instance."

     Okay, so that's the digital version. Now for the twist:

     "Also, since the effect is more or less linear to the magnetic field
     strength, a Hall-effect joystick can be continuously variable."

     Translation: There is also such a thing as an *analog* Hall-effect

     On this subject, Duncan Brown writes that for "Escape from the Planet
     of the Robot Monsters", and "I, Robot" (two Atari games known to use
     an analog Hall-effect joystick), that:

     "There is a circuit board for each axis on the bottom of the stick,
     with a fixed Hall-effect transistor mounted to it. Sliding dangerously
     close to it is a little rod magnet, moved by the motion of the stick."

     The bottom line is that Hall-effect sticks are often a pain to deal
     with. They're very reliable, but because of their complexity and
     relatively complicated mode of operation, were never widely used.
     Since they weren't widely used (and since they were more expensive to
     construct in the first place), they're fairly rare, and potentially
     very expensive.

     Indeed, the only reason we suggested that you might be able to find
     them cheaply is because of their rarity -- while rarity often implies
     value to a collector, their nonstandard nature can also lead operators
     to discard them as worthless. The logic is similar to that described
     in reference {9.3.3} (Buying from an Operator FAQ ) with respect to
     vector monitors. They may be rare and valuable to a collector, but for
     this very reason, may also have little or no value to an operator.

     One final word. Rumor has it that people have managed to hack analog
     joysticks to replace analog hall effect sticks. If you find any
     definitive information on this, or (better yet) if you've actually
     *done* it, post about it to r.g.v.a.c. The world will thank you, and
     we'll also be able to add more value to this FAQ.

Encoder Wheels (Trakballs, knobs, and steering wheels)
     Encoder Wheels are used wherever both the a speed and direction of a
     freely-rotating object are required for game play. Examples of games
     that use this technology are any game with a trakball (Missile
     Command, Centipede) or free-spinning knob (Tempest, Tron), which may
     often be attached to a steering wheel (Pole Position and many other
     driving games).

     The "encoder wheel" itself is a perforated disc that rotates with the
     controller. A pair of photosensors generate square- wave outputs as
     the perforations alternately pass and obstruct light. The end result
     is two square-wave outputs; a clock (CLK) and a direction (DIR). Each
     clock pulse denotes a certain degree of rotation, and the photocells
     are spaced (in accordance with the size of the holes in the wheel)
     such that the two waves will be 90 degrees out of phase, the value of
     the "direction" wave can then be used to determine whether the
     detected rotation occurred to the right or to the left.

     A free-spinning knob requires one encoder wheel. A trakball requires
     two such wheels which are rotated by the ball's movement. One wheel
     measures vertical movement, and the other measures horizontal
     movement, producing four output signals.

Power Supplies

Isolation transformers:
     These aren't really power supplies, but they're an important safety
     feature. If your monitor says "ISOLATION TRANSFORMER MUST BE USED",
     take their advice and use one. Chances are almost certain that if you
     purchased your cabinet in working order, it'll have one already set

     BUT... Suppose you purchased your monitor separately. Perhaps you
     found a nice 15" raster monitor from an old cocktail machine during a
     bulk buy, and you figure it would make a nice piece for your
     workbench. Or you found a whole pile of monitors that the operator
     "just wants to clear out". In these cases, you may not be able to tell
     whether or not you need one. If this is the case, play safe and assume
     you need it anyway.

     Okay, great. Isolation transformers are Good Things, but what the heck
     *are* they, and why do we want to use them?

     An isolation transformer is a safety device that goes between the 120V
     AC coming out of the wall and the monitor. They're often found between
     the 120V AC from the wall and the game's onboard power supply, but can
     also sometimes found between the game's power supply and the monitor.
     The key thing is that they always go between the 120V AC from the wall
     and the monitor; this is how most games are wired -- only the monitor
     AC goes through the isolation transformer.

     To understand why, we'll have to learn a bit about how your home is

     The average North American house has a center-tapped 240V AC signal
     coming in from the outside world. The center tap is connected to earth
     ground at the power distribution box. Ground (the green wire) is
     connected to this center tap through the third wire (safety ground).
     To get 120V AC, you connect (at the distribution box), a white wire
     (neutral) to the ground or center tap, and the black wire (hot) to
     either of the 120V AC terminals. All green and white wires are
     therefore electrically the same at the distribution box. (The
     difference is that the white wire is intended to carry current, and
     the green one isn't - any current in the green wire indicates a

     A monitor has a "hot chassis". AC comes into the monitor, and one side
     is connected to the chassis through the diodes in the monitor's AC->DC
     rectifier. Through these diodes, you have a connection to 120V AC.
     Grabbing such a monitor with bare feet on a concrete floor isn't going
     to be a pleasant experience.

     This is where isolation transformers come in. They're a 1:1
     transformer that keeps the game's electrical GND away from the wall's
     GND. *Neither* of the output wires from the isolation transformer has
     any electrical connection relationship to the green GND wire; i.e.
     earth ground. Theoretically, you should be able to hold either of
     these wires in one hand and ground yourself with the other and remain
     safe. (We don't recommend it due to real-world factors such as leakage
     -- we're just trying to illustrate the point)

     Without such a transformer, this isn't so. And we've already talked
     about the hot chassis, meaning that a game without an isolation
     transformer may have a very different idea of GND than you do. When
     you engage in philosophical discussions with your machine on the
     definition of GND, you'll discover that the game tends to win the
     argument, usually ending the conversation with a nasty shock.

     That's bad enough, but if your hands happen to be tightly wrapped
     around a joystick at the time, and your muscles cramp as a result of
     the shock, you will find it *very* difficult to release your grip;
     muscles work on electrical impulses, and unless your nerves can put
     out 120V AC to override the game's output, or you can move your
     *other* muscles to knock your tightly-gripped hands off the controls,
     the next "cabinet" you work on may be a pine box.

     We say again:

     If the monitor says it needs an isolation transformer, *OR* if you're

Grounding - another safety tidbit:
     Games are meant to be plugged into grounded outlets. If you check your
     house wiring (and live in North America), you'll see that the white
     wire ("neutral") is connected back to the same place as the third
     prong ("safety ground"), while the 120V is supplied on the black wire
     ("hot"). The black wire carries a 120V sine wave centered around (i.e.
     goes 60V above and 60V below) the white wire, which is the same as

     Okay, so if your game grounds its chassis to the white wire, or
     rather, what it *thinks* is going to be the white wire when it's
     plugged in... Imagine a mis-wired socket, or a two-prong plug, that
     gets plugged in the wrong way. Sit this machine next to a
     properly-wired device. Now touch both devices at once. Your next of
     kin will finish reading this FAQ for you.

     The moral:

     Use a properly-grounded outlet -- and a properly-grounded plug. This
     is just basic electrical safety, but you only have to make one
     mistake; in the arcade of life, you start with one life and you don't
     get any bonuses at 10,000 points.

Switching versus linear:
     A linear power supply has a large transformer that takes the 120V AC
     signal from the wall and converts it to a lower AC voltage. It passes
     this lower voltage through a rectifier, which will give you DC. The DC
     won't be flat or steady, but at least you're halfway there. The DC is
     then passed through a filter to smooth it out, and then a voltage
     regulator to obtain the exact voltage.

     All of these steps, when taken together, require a lot of power;
     you're effectively converting excess energy into heat. The
     transformers tend to be extremely bulky, and more often than not,
     rather expensive.

     Whenever possible, use a switching power supply. They're not only
     cheaper and lighter than their old linear counterparts, they're also
     more reliable and produce a cleaner supply for your game. Can't find
     one cheaply? Rip apart an old IBM PC and use its power supply. It will
     supply everything you need for running the average board.

Hacking boards with weird power requirements:
     It's often a good idea to modify a board with strange power
     requirements or a strange sync, so that you can use your existing
     switching power supply and/or monitor. Don't modify the cabinet -
     modify the board since it makes future conversions/board swaps easier.
     Yes, this goes against our earlier advice of being nice to your
     boards, so let's just say it's a judgement call. It depends on your
     taste, your ability, and the odds that you might want to sell or trade
     the board away in the future.

     If you're dealing with weird power requirements as in, say, Pacman
     boards, which convert 7.5V AC; (yes, Seven-and-a-half Volts of
     Alternating Current, which gets stepped down from a linear power
     supply earlier in the cabinet -- see what we mean about linear power
     supplies being potential pains in the butt?) into +5V DC on the board,
     you're pretty safe to modify the board, as you won't be seeing many
     situations where 7.5V AC is supplied.

     If it comes time to sell the board, you'll have a much easier time
     making the sale if it can use "standard" power requirements. In the
     case of Pacman, the modification (which involves only five jumpers) is
     also easily reversible, which is a bonus, just in case you should be
     selling it to someone with an original Pacman cabinet someday.

     If, on the other hand, you're just dealing with something like pins in
     different places, but normal voltages, it's probably best to build an
     external adaptor and include it between the board and the wiring
     harness. This way, you don't run the risk of damaging the board by
     making a mistake, and a future buyer of your board won't have to
     "unfix" it at a later date.

     Meanwhile, the Pacman modification is as follows:

       1. Jumper four wires over the AC->DC rectifier diodes (D3, D4, D7,
          and D8). The idea is to short 'em out; you won't be using them.
       2. Jumper a fifth wire across the large 4-ohm resistor by the heat
       3. Pacman's 7.5V AC pin gets connected to +5V DC from the power
       4. Pacman's GND pin (from the center tap of the 7.5V AC signal) gets
          connected to GND from the power supply.
       5. Pacman's 12V AC pin gets connected to +12 V DC from the power

Ignoring weird power supply requirements in the first place:
     With the appropriate modification, almost any board with oddball power
     requirements (like the +25V Atari used to store high scores in the
     non-volatile RAM on older games like Centipede) can be powered by a
     standard switching power supply with +5V, -5V and +12V.

     For instance, ignoring the +25V in the example above will still result
     in a playable game; only the behavior of the high score table will be
     affected. If you can live without such functions (or provide the same
     functions, say with an external sound amplifier), then you can forget
     about these oddball voltages. Sometimes, lower DC voltages can often
     make good substitutions for odd voltages. For instance, Williams sound
     boards "require" a -12V DC signal, but you can get away with a more
     standard -5V DC signal instead.

          If you are applying a voltage to a board that's not specified in
          the manual as the correct voltage, then you *are* taking a risk
          that might fry your board. Be *VERY* careful as you try to
          substitute different voltages/circuits in an attempt to avoid
          using an oddball voltage, and make sure you understand (using the
          schematics and your knowledge of electronics) what the board is
          trying to do with that oddball voltage before you start.

     Another example of applying a little understanding to a problem would
     be the Pacman modification discussed above. Elsewhere on the board, a
     12V AC signal is used to generate +16V DC for the audio circuitry. A
     look at the schematic reveals that the audio op-amps are the only
     place where the +16V DC is used, and a databook tells you that the
     chips in question can also be powered with +12V DC. Since you *know*
     what the board wants and what it can handle, you can use this to
     design your workaround. This is part of the reason why the hack to
     Pacman discussed above allows you to get away without using the
     original Midway power supply.

     In an interesting twist of fate, and an example of how various
     manufacturers "borrowed" from each other during the industry's early
     days, note that Sega's "Super Moon Cresta" uses exactly the same power
     scheme as does Midway's "Pacman". Same hack to convert to DC, same
     power and video pins, same bloody *PARTS* in the same *LOCATIONS* on
     the board, etc... So if you get a sense of deja vu when hacking on an
     old board, don't ignore it. You probably *have* seen it before.

Geographical considerations:
     In North America, the power that comes out of your wall socket is 120V
     AC. This assumption does *not* hold true for Europe, where 240V AC is
     the norm.

     Some power supplies have little switches on them to switch between
     120V AC and 240V AC inputs. Others (Atari linear power supplies in
     particular) have "voltage selection plugs" that can be used for the
     same purpose.

     If you don't know what type of power your power supply expects, and
     especially if you've received parts from overseas, take a few minutes
     to check.


Horizontal versus vertical:
     Don't bother rotating a monitor from vertical to horizontal (or vice
     versa). Just buy another cabinet with a monitor oriented the correct
     way. You'll save yourself a lot of headaches (and back pain) in the
     long run.

     There are two exceptions to this rule: Sega's "convert-a- cabinet"
     system (used on their vector games) included slots to allow the
     monitor to be removed and rotated easily, and some of the new
     higher-end JAMMA cabinets, which have a swivelling monitor which can
     be rotated from horizontal to vertical without having to remove it.

     Actually, there's one other exception. Don't use a cabinet! If you're
     not worried about appearance, your setup can be as simple as a power
     supply, harness, joystick, and monitor on a workbench. Rotating the
     monitor in this kind of a situation is a piece of cake :-)

Swapping outputs to rotate:
     It's possible to avoid the problem of rotating monitors with vector
     games; you can put the vertically-oriented Tempest in any other Atari
     color vector cabinet, which will be horizontally-oriented. You can
     sometimes swap the X and Y outputs on the Tempest board and shrink the
     dimensions with the adjustments on the game board to get it playing on
     a horizontally mounted monitor. Some monitors (and some Tempests :-)
     seem to cooperate, and some won't. Give it a try and see what comes

     Alas, this trick only works because the game has a vector display.
     There is *NO* way to "swap and shrink" the signals meant for a raster
     display. Sorry.

Vector monitors and power supplies:
     Atari B/W vector monitors want a 60V AC power supply. Atari color
     vector monitors want a 50V AC power supply. Yes, sixty for one, and
     fifty for the other. (We don't make the rules, we just follow 'em...)

     The bottom line is that you *CANNOT* swap power supplies from a B/W
     vector game cabinet into a color one. Don't try. Since the power
     supplies look identical, this can be a real problem. If there's any
     doubt about which is which, disconnect the power supply, turn it on,
     and measure the voltage at the source.

     Most vector monitors from one manufacturer are incompatible with games
     from other manufacturers. One notable exception to this rule is Omega
     Race, which uses a monitor identical to the ones used in all of
     Atari's B/W vector games.


     The JAMMA standard was invented in 1985; any game older than this will
     not be JAMMA. For reference, here is the JAMMA pinout:

        Solder Side            |          Parts Side
            GND            | A | 1 |          GND
            GND            | B | 2 |          GND
            +5V            | C | 3 |          +5V
            +5V            | D | 4 |          +5V
            -5V            | E | 5 |          -5V
            +12V           | F | 6 |          +12V
           - KEY -         | H | 7 |         - KEY -
        Coin Counter #2    | J | 8 |      Coin Counter #1
        Lock Out Coil #2   | K | 9 |      Lock Out Coil #1
        Speaker (-)        | L | 10|      Speaker (+)
                           | M | 11|
        Video Green        | N | 12|      Video Red
        Video Sync         | P | 13|      Video Blue
        Service Switch     | R | 14|      Video GND
        Tilt Switch        | S | 15|      Test Switch
        Coin Switch #2     | T | 16|      Coin Switch #1
        2P  Start          | U | 17|      1P  Start
        2P  Up             | V | 18|      1P  Up
        2P  Down           | W | 19|      1P  Down
        2P  Left           | X | 20|      1P  Left
        2P  Right          | Y | 21|      1P  Right
        2P  Button 1       | Z | 22|      1P  Button 1
        2P  Button 2       | a | 23|      1P  Button 2
        2P  Button 3       | b | 24|      1P  Button 3
                           | c | 25|
                           | d | 26|
            GND            | e | 27|          GND
            GND            | f | 28|          GND

     We're also including the Konami standard pinout, as it was also used
     on many games by many different manufacturers.

        Solder Side            |          Parts Side
            -5V            | A | 1 |         +12V
        Speaker            | B | 2 |      Speaker
        2P  Button 2       | C | 3 |      2P  Button 1
        2P  Left           | D | 4 |      2P  Right
        1P  Start          | E | 5 |      2P  Start
        1P  Button 2       | F | 6 |      2P  Up
        1P  Button 1       | H | 7 |      Service Switch
        1P  Right          | J | 8 |      1P  Left
        1P  Up             | K | 9 |      2P  Down
        Coin  (1)          | L | 10|      Coin  (2)
        1P  Down           | M | 11|      Coin Counter #1
        1P  Button 3       | N | 12|      Coin Counter #2
        Video Green        | P | 13|      Video Blue
        Video Red          | R | 14|      Video Sync
                           | S | 15|
            GND            | T | 16|          GND
            GND            | U | 17|          GND
            +5V            | V | 18|          +5V

Identifying pinouts:
     Identifying pinouts of unknown boards can be difficult. We offer the
     following approach:

       1. Do you already have a copy of the game's pinout? If so, you're
          done. (Make sure you've got the *right* copy of the game's
          pinouts. Moon Cresta, for instance, was made by at least four
          different manufacturers, three of whom used different pinouts...)

       2. Is the manufacturer shown? If so, who are they, and do you have
          any copies of pinouts by the same manufacturer? If so, compare
          them; do they "make sense" if you try them against the method
          outlined in steps 4-8) below?

       3. If it's a Japanese name, and a fairly new board, and it's got a
          56-pin connector, it's probably JAMMA. Still, it always pays to
          double-check before you plug something in based on your
          assumptions. There *ARE* 56-pin connectors which aren't JAMMA, so
          the double-check is still important.

       4. Okay, now you're desperate :-) Get a list of all the pinouts that
          you *DO* know.

       5. Eliminate any pinouts with connectors that don't match the board
          in question.

       6. Look at telltale markers, like the power pins; you should be able
          to identify +5V and GND fairly easily by tracing backwards from
          some TTL chips. Using this, and the number of pins on the
          connector, should allow you to eliminate a few more pinouts.

       7. With the few pinouts you have left, look for audio and video
          pins. These are generally grouped together; two pins going to the
          same location (often a heat-sinked audio amplifier chip) will
          probably be audio, and four pins, three of which go to one chip
          and a fourth of which goes to a nearby chip, will likely be
          video. Large groupings of pins that go through resistors and/or
          diodes will likely be control input pins.

       8. *NOW* do you have a match? If so, start "experimenting"; make a
          few assumptions and try powering the board up without any video
          or controls connected and "experiment" by looking for fluctuating
          signals (characteristic of video or audio) on the pins. This is a
          fairly involved process, but can be simplified greatly by use of
          a partially- constructed adaptor to your current wiring harness.
          (Indeed, this is one of the reasons adaptors are fairly popular;
          they often get created through the process of determining the
          pinout from an otherwise unknown board)

          Note that this can be something of a risky procedure if you don't
          know what you're doing. For your first few times, you may want to
          do everything except powering up the board: write down your best
          guesses, describe the board, and ask the 'net if anyone out there
          recognizes it and knows the pinouts. You might just get lucky,
          and if your guesses were right, you'll give your self-confidence
          a great boost.

          Rick Schieve has written an excellent text file on this subject;
          see reference {9.3.4} for details. John Keay has another method
          for quickly identifying and recording pinout information; see
          reference {9.3.5} for details.

Unused connectors:
     If there are empty connectors on the board, don't panic. Some boards
     have "test connectors" that are unused during normal use. If you don't
     know whether a certain board or board set is complete, ask the 'net if
     anyone knows "how many boards and connectors were used in XYZ".


     Adaptors are one of the easiest and cheapest approaches to doing
     conversions; this is why JAMMA cabinets are so popular among
     collectors, even among those of us who prefer "classic" games. Large
     collectors will often accumulate a series of adaptors for their games,
     all of which convert to a standard pinout, usually JAMMA. Although the
     process is the same as building any other type of adaptor, the
     "random-raster-game to JAMMA" conversion is so common that it has
     become known colloquially as "Jammatization".

Construction techniques:
     There are two main approaches to adaptor construction. The "right"
     approach for you will depend on what set of parts you can most easily

     Both approaches involve an XX-pin (female, and "XX" depends on the
     board in question) edge connector for the non-JAMMA board and a 56-pin
     "finger board" (a straight piece of PCB, also known as a
     "male-to-male" connector), and a 56-pin (female) edge connector for
     the JAMMA side.

       1. Skip the 56-pin connector and solder the wires directly from the
          XX-pin connector to the finger board. The resulting finger board
          end of the adaptor can be plugged directly into your JAMMA
          harness. You'll use one finger board per adaptor.

          The end result would look something like this:

                  --------< <---------->~~~~~\/~~~~~~~~~~------<
          TO      --------< <---------->~~~~~'\/~~~~~~~~~------<  DIG
          JAMMA   --------< <---------->~~~~~~'\/~~~~~~~~------<  DUG
          WIRING  --------< <---------->~~~~~~~'`~~~~~~~~------<  PCB
          HARNESS --------< <---------->       /~~~~~~~~~------<
                  --------< <---------->~~~~~~'
                   56-pin     male-male  Wires that map  44-pin
                   female     PCB with   JAMMA pinouts   female
                   edge       straight   to 44-pin Dig   edge
                   connector  traces     Dug pinout.     connector


       2. Instead of soldering the wires to the finger board, solder the
          wires from the XX-pin connector to a 56-pin connector. Plug one
          end of the finger board into the 56-pin connector, and the other
          end into your JAMMA harness.

          Rather than using a finger board for each adaptor, you're using
          one 56-pin connector per adaptor, as the finger board can be used
          between different adaptors.

          The end result was shown in section {5.3}, but is reproduced here
          for quick reference.

                  -------< <----------> >---------~~~~~\/~~~~~~~~~------<
          TO      -------< <----------> >---------~~~~~'\/~~~~~~~~------< DIG
          JAMMA   -------< <----------> >---------~~~~~~'\/~~~~~~~------< DUG
          WIRING  -------< <----------> >---------~~~~~~~'`~~~~~~~------< PCB
          HARNESS -------< <----------> >---------       /~~~~~~~~------<
                  -------< <----------> >---------~~~~~~'
                   56-pin    male-male   56-pin    Wires that map  44-pin
                   female    PCB with    female    JAMMA pinouts   female
                   edge      straight    edge      to 44-pin Dig   edge
                   connector traces      connector Dug pinout.     connector

          Like we said right at the introduction, the "right" approach for
          you depends on your resources; this is a perfect example. If you
          live near a surplus store that has 56-pin female edge connectors
          for $1.00 apiece, but you only have a few finger boards, grab a
          big pile of connectors go with method 2. If it's easier to use
          mail-order, and finger boards are half the price of edge
          connectors, get a big pile of finger boards and go with method 1.

RGB, Sync, polarity, and all that rot. (Stupid Video Tricks, Part I)

The Basics:
     Rick Schieve has written a text file on raster video basics; check out
     reference {9.3.6} (Raster Monitors) in the bibliography for more
     information, but we'll summarize the high points here:

     All raster monitors use generally the same set of inputs: RGB, and
     some form of sync. RGB stands for "Red, Green, and Blue", and denotes
     the colors of the beams. Sync is for "synchronization", the process by
     which the electron beam in a raster monitor sweeps across the screen.

     (You may have heard the terms "horizontal", "vertical", and
     "composite" sync. For now, just consider "horizontal" sync to be the
     sync pulse at the end of each line on the screen, the "vertical" sync
     to be the pulse at the end of each screenful of data, and "composite"
     sync to be a magical combination of both. We'll get into the gory
     details soon enough :-)

     So far, so good, right?

     Wrong. While all these signals are common to raster games, they come
     in different (and alas, incompatible) flavors. Working around these
     difficulties can be one of the more confusing problems for someone
     doing conversions. That's where this FAQ comes in. We'll try and
     describe the common variants, and give a few examples of games that
     use them. You should be able to extend the approach to other games.

RGB polarity
     While all raster monitors accept RGB inputs, they can have either
     positive or negative logic. The majority of games use positive logic
     (when the voltage is on, the electron gun turns on, and you get a
     bright image), but Nintendo games use negative logic, which works the
     other way around.

     RGB signals are analog signals; you'll need an analog inverter to get
     around the problem; a CMOS hex inverter (say, a 4069), which is
     designed to invert digital signals, won't work. To be more precise, it
     theoretically *shouldn't* work, but on the practical side, a few
     people have tried it and actually managed to make it work. Your
     mileage may vary. One tip: if you try this, make sure you ground all
     of your unused inputs.

     Meanwhile, the "right way" is to use an analog inversion circuit for
     each of the three RGB signals. It requires a +12V, -12V, and -5V
     supply, but some power supplies will supply all three voltages. Thanks
     to Paul Kahler for the original schematic and document (see reference

                            |                   |
                            |     |\   +-- +12V |
                  R1        |     |  \ |        |
     Input ------/\/\/------+-----|-   \        |
                            |     |LM318 \______|_______ Output
     -5V --------/\/\/------+  +--|+    /
                  R2           |  |   /|
                               |  | /  |
                               |       +--  -12V

     R1, R2, and R3 are all identical resistors.  A value of roughly
     10K should provide good results.  The LM318 is a high-frequency
     op-amp.  Its pinouts are as follows:

                            1 Comp/bal     8 Comp
                            2 -in          7 V+
                            3 +in          6 output
                            4 V-           5 Comp/bal

     The "Comp" pins may be ignored.  An LF356 might also work, but
     the 741 is not recommended.

Sync polarity:
     Now that we can generate the RGB signals our monitor requires, we
     still have to put the signals on the screen in an orderly fashion. The
     is what the "sync" signals are for.

     Again, we run into the problem that some boards produce negative sync,
     and some don't. Fortunately, since all sync signals are digital, the
     process is much simpler; using a *really* fast CMOS hex inverter is a
     perfectly legitimate way around the problem. A TTL inverter should
     also work; all sync signals generally operate at TTL levels. Still,
     this is dicey business, so your mileage may still vary.

Composite versus Separate Sync:
     Now that you know how to invert syncs, you're ready for the last bit -
     the two flavors of syncs and how to mix and match them.

     Older monitors often had separate sync inputs; one for horizontal sync
     (the retracing of the beam across the screen), and one for vertical
     sync (the return of the beam from the bottom of the screen to the top
     of the screen).

     Newer games (but also many older ones) used monitors which accepted
     composite sync; the two signals were combined together on the board,
     and a bit of circuitry in the monitor determines whether a given sync
     pulse is a horizontal or vertical retrace.

     If you have an older game that outputs separate syncs, and a newer
     monitor that can only accept composite sync, you can combine the two
     using digital logic. Simply "OR" the two signals together with a TTL
     chip to obtain the composite sync signal.

     Since both composite and separate syncs can be positive or negative,
     it may be necessary to invert the composite sync signal after the
     ORing stage. If this is the case, just use a NOR gate instead.

Sync shortcuts:
     If you've got schematics for your games, take a closer look at them.
     The game's wiring harness may show separate syncs, but the schematic
     itself may show that there are unused pins for composite sync. All the
     old Williams games (Defender, Stargate, Joust, Robotron, etc...) are
     like this, as is Atari's Missile Command.

     A little schematic-browsing can make your life much easier.

     One last cheat -- if your monitor only supports separate sync, you may
     be able to get away with connecting a composite sync signal to either
     the horizontal input or to both inputs. No guarantees, but you might
     as well try it as a "first shot".

Inversion. (Stupid Video Tricks, part II)

Smoke and mirrors:
     Some games have mirrors in the cabinets which reflect the video
     output. This is great, if you're playing Asteroids Deluxe in the
     original cabinet. This sucks, however, if you're trying to put an
     Asteroids Deluxe boards in a conventional Asteroids cabinet. Most of
     these games have pins on their edge connectors for X- and Y-inversion;
     pulling these pins high (+5V) or low (GND) will invert the image in
     the appropriate axis. Play around until you've got something that
     looks right on your screen.

Cocktails, anyone?
     To further complicate things, some games have "cocktail" pins, which
     are pulled high or low depending on the wiring harness. On upright
     games, the signal on the "cocktail" pin tells the game *not* to invert
     the image when player 2 is up. On cocktail machines, the signal tells
     the game *to* invert player 2's image.

     Finally, and this is the *really* weird one, some games use both
     approaches -- a PLAYER1 and a PLAYER2 pin, for instance, were used on
     the Asteroids cocktail machine, both to activate and de-activate the
     two players' control panels, but also to control video inversion.

     Our point here is not to confuse - merely to say that if the game
     appears upside-down or backwards for no apparent reason, you should
     probably take a closer look at the pinouts. It's amazing the number of
     variations that are out there, and it's sometimes a miracle that
     things show up correctly at all! Again, our earlier rule of thumb
     applies: If you don't like what you see, play with it until you do.

     As a last shot - sometimes it's not on the pins at all. More recent
     games control their "cocktail" versus "upright" behavior by means of a
     DIP switch setting. Fiddle with these if you think you've tried

It's *STILL* upside-down!
     Finally, with vertically-mounted games, there are no guarantees. Some
     manufacturers believed that a monitor should be rotated 90 degrees to
     the right, and some believed it should be rotated 90 degrees to the
     left. So you're not the only person who's confused. The whole industry
     was confused at one time or another, and this is the historical

     What this means is that if you've tried all of the above techniques,
     and you've got a game designed for a vertically- mounted monitor, you
     may be out of luck. The manufacturer of that game used the same
     monitor, but they turned it the other way around.

     You can get around this by reversing the wires to the deflection coils
     on the neck of the monitor (and if you're really fancy, installing a
     switch to go back and forth whenever you like), but like most monitor
     work, this is a fairly advanced modification, and we recommend that
     you be absolutely certain that you know what you're doing before you
     try this.

     Remember, monitor hacking can be a dangerous sport unless you know
     what you're doing and take proper safety precautions. Keep in mind
     that with all the space you've saved doing conversions, you can
     probably squeeze in another cabinet. Replacing *yourself* is much more
     difficult. If you've never hacked on a monitor before, ask some folks
     on the 'net about proper safety procedures (such as discharging the
     tube, etc.) before you begin.


     EPROMs are Erasable-Programmable Read-Only Memory chips. They are the
     primary means of storing game program data. You'll often see people
     "looking for EPROMs", particularly if their machine isn't working.

     EPROM programmers are devices used for (surprise!) programming EPROMs.
     They are also referred to as "burners", as the process involves
     "zapping" the memory cells with high voltages in order to get them to
     change state to store the data.

     EPROM erasers generate concentrated UV light and shine it through the
     little glass window onto the chip; the exposure to the UV light is
     what erases the data. EPROMs are often covered with small sickers; the
     idea isn't just to put a label on the chip, but to prevent stray light
     from outside (which may contain some UV radiation at the proper
     frequency) from hitting the chip -- it may take several days or weeks
     of bright sunlight to completely erase a whole chip, but it only takes
     one erased bit to render a video game inoperative.

     Owning an EPROM programmer and eraser is a Good Thing. If you get a
     new game, you can read in the EPROMs and store their data on your PC.
     If an EPROM dies at any time in the future, you can get a new one (or
     erase the old one and try to re-use it) and program it with the data
     you archived. Several programmers exist for the IBM PC; these cost
     roughly $100-$200. EPROM erasers cost roughly $50-$100.

     PROMs are Programmable Read-Only Memories. The key is that they're
     programmable, but *not* erasable. They're programmed by applying
     voltages similar to those used in EPROM programming, but they work by
     blowing tiny fuses on the chip itself; once you've programmed a PROM,
     there's no way to erase it and reuse it. Once a PROM fails, it has to
     be replaced.

     PROMs can be much simpler and faster (electronically-speaking) than
     EPROMs, which is why you'll often see very small PROMs on games --
     14-pin chips that hold a few hundred bytes of data needed for the
     circuitry to work properly, etc...

     Programmers that will handle PROMs and other types of programmable
     logic are more expensive than simple PC-based EPROM programmers; check
     with an electronics supply house for pricing, which should be in the
     $400-$800 range, depending on what you need. Yes, this is outside the
     price range of most video game collectors, and yes, a simple EPROM
     programmer will suffice for most of your needs, so if you're looking
     at investing in a high-end programmer, make sure you know you need it
     first :-)

     RAMs hold Random Access Memory. This is primarily used for such things
     as the state of the screen, the position of the enemy aliens, and your
     current score. There isn't much to say about RAM, other than that when
     it fails, you need to replace it, and that parts for older games are
     becoming more expensive as time goes by.

     If you're ever in a surplus store and you see an old motherboard (be
     it from an arcade machine or not) that's full of RAM chips, and you
     know you've got a game that uses the same type of chip, do yourself a
     favor and pick it up if the price is right. You can often get 20-30
     chips for the price of one. Removing the chips from the board is often
     difficult, but at a 97% discount, it's worth the time.

NOVRAMs, EAROMs, CMOS RAM, ZRAM, and other exotic beasts:
     Some games keep track of information even when the power is turned
     off. NOVRAMs (NOn-Volatile RAMs), EAROMs (Electronically-Erasable
     ROMs), and CMOS RAM (Complimentary Metal Oxide Semiconductor RAM) are
     popular technologies with older (and some newer) games. A new
     technology, ZRAM (ZeroPower(tm) RAM), has also emerged in the past few

     Some of these technologies require weird voltages, which is why some
     games require weird voltages. For instance, NOVRAMs and EAROMs (used
     in many Atari games) may be read at +5V, but written at +25V. You can
     play the game at normal voltages, but the all-time high scores will
     not be preserved.

     Old Williams games used CMOS RAM powered by batteries on the main
     board. When the power is turned off, the RAM draws tiny amounts of
     power from the batteries to keep itself alive. We mention this here
     because one of the most common "horror stories" with such games is for
     the boards to be thrown into storage with the batteries still mounted.
     Five years later, when *you* come on the scene, you find the board of
     your dreams, only to find a mass of corroded metal where the batteries
     once were.

     The solution to a collector is simple; wire up an external battery
     pack to the original setup, keeping the batteries *AWAY* from the main
     board. If the batteries fail, your boards will remain safe.

     ZRAM is neat. Fed up with all the hassles of batteries, a genius at an
     electronics firm decided to include the battery with the RAM chip. The
     resulting product was called ZeroPower RAM, or ZRAM for short. The
     specifications for one such chip, the 48Z02, claim that the lifetime
     of the battery is solely dependent on the temperature -- an average
     chip will have a battery lifetime of 20 years at 70 degrees C, and 99%
     of chips will have a lifetime of 11 years at 70 degrees C.

     An example of a hack that uses ZRAMs in a modern video game is John
     Keay's hack which allows a Battlezone machine to keep track of its
     high scores. See reference {9.2.3} for details.

Cabinet Maintenance:

Refurbishing control panels:
     In the rush to get the power supplies, boards, monitors, and other
     stuff working, you may end up neglecting some basic woodworking and/or
     metalworking tasks. Take a few moments and work on the control panel;
     you're putting this game on display for yourself, and it should look
     as good as you can reasonably make it. A former operator shared a
     quick guide to fixing up control panels:

       1. Completely strip the front panel and remove it. This may also
          involve removing bits and pieces of the old plastic artwork that
          covered it.

       2. Depending on the requirements for the new control panel, drill
          out whatever holes you require. Try to do this with an eye to
          reusing as many of the old holes as possible. The cheap hole-saw
          sets found in hardware stores for $5-6 can be great for this
          task, but if you have a real screw punch, go ahead and use it.

       3. Once all the holes are drilled (including any mounting holes for
          the bolts that will attach large items like joysticks and flight
          controls), cut a piece of clear plexiglass to the same size as
          the largest flat piece of the control panel. Duplicate the panel
          holes in the plexiglass.

       4. Cover the metal control panel with some attractive plastic
          artwork. Affix any button labels or instruction sheets to the
          plastic. If there are any unused holes in the metal, the artwork
          will cover them, and the plexiglass will protect them from being
          accidentally poked out.

       5. Generic artwork is available in large sheets from most arcade
          suppliers, but the original decals for classic games have become
          extremely rare over the years.

       6. Mount the joysticks and buttons, putting them through the
          plexiglass and into the control panel. Attach any necessary
          carriage bolts to hold the thing together.

       7. Solder the leads to the controls, and you're done.



Numerous folks have contributed to the Conversion FAQ by providing detailed
conversions to show the reader the different approaches in action.

Please consider carefully before contacting these authors, as plenty of
folks try these conversions every year. If they all contacted the author
whenever they had trouble, the author would have very little time to work
on his/her *own* collection, let alone write up new conversion material.

Simply put, take the time (and we mean *your* time :-) to figure out what
went wrong before running to the authors. Start by trying to get the
original pinout/schematic info. If you still can't figure out what
happened, describe your problem in a post on r.g.v.a.c., and see if someone
else responds. They may see something in your description that you didn't,
or remind you of something you forgot.

If that still doesn't help, the authors will be much more inclined to help
you debug things now that you've gone through most of the "easy" stuff
yourself, because by this time, you may have found a real *bug* in their
docs, and they'll be just as eager as you are to solve the problem. If an
author's e-mail address isn't included in their conversion document,
consult their VAPS entry for contact information.

Okay, you asked for it, you got it. Here's a list of all the conversions
(as of this writing) on the 'net. We also include a few handy hacks, and a
whole mess of reference material. If you build your own conversion and/or
write up some material of your own and want to tell the world about it,
then please do so!

Everything listed under section {9.1} , "Conversions", appears on the
wiretap.spies.com FTP site under "game_archive/conversion".

The directory structure may be modified from time to time, but you should
still be able to find the conversion you're looking for. Most of the other
material is also available at wiretap.spies.com; please check there first
before requesting a copy from the authors.

   * Conversions:
        o Asteroids <-> Asteroids Deluxe
          (Doug Jefferys)
        o Space Duel -> Gravitar
          (John Lee)
        o Joust -> JAMMA
          (Graham Bisset)
        o Rip Off / Star Castle / Armor Attack <-> Rip Off, Star Castle,
          Armor Attack, Solar Quest
          (Steve Ozdemir)
        o Gravitar <-> Black Widow
          (Doug Jefferys)
        o Robotron / Joust <-> Robotron, Joust, Stargate
          (Doug Jefferys)
        o Upgrade from Robotron/Joust/Stargate to include Bubbles
          (Doug Jefferys)
        o Gravitar -> Tempest
          (Rick Schieve, Steve Ozdemir)
        o Gravitar -> Major Havoc
          (Tony Jones)

   * Hacks:
        o Sinistar Joystick Hack
          (Lee Crawford)
        o Nintendo color video inverter
          (Paul Kahler)
        o Adding high-score battery backup feature to Battlezone
          (John Keay)

   * Reference material:
        o Addresses FAQ (a list of video-game related parts sources)
          (Tony Jones)
        o The Pinouts and Switches Archive (FTP to wiretap.spies.com)
          (Multiple authors)
        o Buying from an Auction FAQ
          (Doug Jefferys, Steve Ozdemir)
        o How to identify an unknown board
          (Rick Schieve)
        o Quick-reference pinouts
          (John Keay, Frederic Vecoven)
        o Raster Monitors
          (Rick Schieve)
        o How to Diagnose, Repair, and Upgrade Ampliphone and Wells-Gardner
          Color Vector Monitors
          (Gregg Woodcock, Rick Schieve)
        o Building a JAMMA cabinet
          (Rick Schieve)
        o The Video Game Industry Learns from the Data Communications
          Industry (a review of the origins of JAMMA)
          (Noel Tominack)
        o The Williams Hardware File
          (Rick Schieve, Gregg Woodcock)
        o The Cinematronics History File (technical overview and design
          history of Cinematronics)
          (Steve Ozdemir)
        o Buying from an Operator FAQ
          (Doug Jefferys, Steve Ozdemir)
        o R.G.V.A.C. FAQ
          (Tony Jones)

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