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1.0) Conversion FAQ:
--------------------

COPYRIGHT 1994

REVISION NUMBER: 1.1
REVISION DATE: 02 November 1994

REVISION HISTORY: 1.1 (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})
REVISION HISTORY: 1.0 (01/11/94 - First public release; FTP only)

CREATED BY: Doug Jefferys, Steve Ozdemir

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


STANDARD DISCLAIMER:
--------------------

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.


2.0) Introduction:
------------------

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 guaranteed.

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.


3.0) 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:

3.1) Monitor
     - That TV-like thing that displays the pretty pictures.  
       Monitors come in two flavors:  Vector and raster.
     - 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.
     - 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.
     - 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.
     - 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 expects.

3.2) Controls
     - All controls perform the same function:  conveying your 
       actions to the game board.
     - 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.
     - 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.
     - 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.
     - 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.

3.3) Speakers
     - 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.
     - Amplified signals are the easiest to deal with.  Stick 'em 
       onto your speakers and enjoy the sound.
     - 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. 
     - 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.
     - 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!

3.4) Power supplies
     - Turns ugly 120V AC power into nice, clean DC voltages usable 
       by the board's electronic components. 
     - 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.
     - Switching power supplies are much lighter, cheaper, and easier
       to work with.  
     - 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.
     - 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.
     - "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.
     - 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 games.

3.5) Boards
     - 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.

3.6) Wiring harness
     - 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 :-)
     - 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.

3.7) Cabinet
     - 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...
     - 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.

3.8) Miscellaneous/specialized/custom/unique hardware
     - Spherical mirrors that reflect the image up (e.g. Time 
       Traveler)
     - 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 information.
     - 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).
     - 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. 
     - Keyboards (Thayer's Quest, Space War)
     - Joysticks with spinning knobs on the ends (Ikari Warriors)


4.0) 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.

4.1) 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

4.2) Raster game conversion classes:
     - Atari
       - Centipede, Millipede, Xevious, Dig Dug, etc...
     - Gottlieb
       - Mad Planets, Reactor, Q*bert
     - Midway
       - Galaga, Bosconians, Mappy
     - Midway
       - Tron, Discs of Tron
     - Nintendo
       - Mario Brothers, Donkey Kong, DK Jr., DK III, Popeye, etc...
     - Pacman
       - 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...)

4.3) 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 Castle.
     
     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 cabinet.
     
     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!


5.0) 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 methods.


5.1) "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 first.

     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.


5.2) 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.


5.3) "Adaptor-hackery":

     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 harness.

     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.


5.4) "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 design...

     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? :-)


5.5) "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 difficult.
     
     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.


6.0) 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.


6.1) 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.


6.2) 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
     conversions.


6.3) 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
     conversions.


6.4) 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
     conversions.


6.5) 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.
  
  
6.6) 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 enjoy.
 
     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.
  

7.0) 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.

7.1) 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.

7.2) 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.

7.3) 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 companies...)

7.4) 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.

7.5) 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.

7.6) 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.


8.0) Miscellaneous Tips
-----------------------

8.1) Controls

8.1.1) Buttons:

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

8.1.2) 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).

8.1.3) Digital joysticks:

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

8.1.3) 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.
 
8.1.4) 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.

8.1.5) 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 manufacturer.

       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 joystick.  
       
       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.

8.1.6) 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.


8.2) Power Supplies

8.2.1) 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 up. 

       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 wired...

       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 fault...)

       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 not sure -- GET ONE AND INSTALL IT BEFORE POWERING UP.

8.2.2) 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 ground.

       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.

8.2.3) 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.

8.2.4) 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 sink.

       3) Pacman's 7.5V AC pin gets connected to +5V DC from the 
          power supply.

       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 supply.

8.2.5) 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.

       NOTE: 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.

8.2.6) 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.


8.3) Monitors

8.3.1) 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 :-)
       
8.3.2) 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 out. 

       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.

8.3.3) 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.


8.4) Pinouts

8.4.1) JAMMA:

       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  
      ----------------------------------------------------------

8.4.2) Konami:

       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
       ------------------------------------------------------

8.4.3) 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.

8.4.4) 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".


8.5) Adaptors:

8.5.1) Jammatization:

       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". 

8.5.2) 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 replace.

       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
        
       Alternatively...

       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.


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

8.6.1) 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.

8.6.2) 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 {9.2.2}).

                                     R3
                              +-----/\/\/---------+
                              |                   |
                              |     |\   +-- +12V |
                    R1        |     |  \ |        |
       Input ------/\/\/------+-----|-   \        |
                              |     |LM318 \______|_______ Output
       -5V --------/\/\/------+  +--|+    /
                    R2           |  |   /|
                                 |  | /  |
                                 |       +--  -12V
                                 GND
       
       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.

8.6.3) 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.

8.6.4) 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. 

8.6.5) 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".
       
 
8.7) Inversion.  (Stupid Video Tricks, part II)

8.7.1) 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.

8.7.2) 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 *everything*...

8.7.3) 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
       result.
       
       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.


8.8) Memories...

8.8.1) EPROMs:

       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.

8.8.2) PROMs:

       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 :-)
       
8.8.3) RAMs:

       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.

8.8.4) 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 years.
       
       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.


8.9) Cabinet Maintenance:

8.9.1) 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.  


9.0) Bibliography
-----------------

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.


9.1) Conversions:

9.1.1)  Asteroids <-> Asteroids Deluxe 
        (Doug Jefferys)

9.1.2)  Space Duel -> Gravitar
        (John Lee)

9.1.3)  Joust -> JAMMA 
        (Graham Bisset)

9.1.4)  Rip Off / Star Castle / Armor Attack <-> Rip Off, Star Castle, 
        Armor Attack, Solar Quest 
        (Steve Ozdemir)

9.1.5)  Gravitar <-> Black Widow 
        (Doug Jefferys)

9.1.6)  Robotron / Joust <-> Robotron, Joust, Stargate 
        (Doug Jefferys)

9.1.7)  Upgrade from Robotron/Joust/Stargate to include Bubbles 
        (Doug Jefferys)

9.1.8)  Gravitar -> Tempest 
        (Rick Schieve, Steve Ozdemir)

9.1.9)  Gravitar -> Major Havoc 
        (Tony Jones)


9.2) Hacks: 

9.2.1)  Sinistar Joystick Hack 
        (Lee Crawford)

9.2.2)  Nintendo color video inverter 
        (Paul Kahler)

9.2.3)  Adding high-score battery backup feature to Battlezone 
        (John Keay)


9.3) Reference material:

9.3.1)  Addresses FAQ (a list of video-game related parts sources)
        (Tony Jones)

9.3.2)  The Pinouts and Switches Archive (FTP to wiretap.spies.com)
        (Multiple authors)

9.3.3)  Buying from an Auction FAQ 
        (Doug Jefferys, Steve Ozdemir)

9.3.4)  How to identify an unknown board 
        (Rick Schieve)

9.3.5)  Quick-reference pinouts
        (John Keay, Frederic Vecoven)

9.3.6)  Raster Monitors 
        (Rick Schieve)

9.3.7)  How to Diagnose, Repair, and Upgrade Ampliphone and 
        Wells-Gardner Color Vector Monitors 
        (Gregg Woodcock, Rick Schieve)

9.3.8)  Building a JAMMA cabinet 
        (Rick Schieve)

9.3.9)  The Video Game Industry Learns from the Data Communications 
        Industry (a review of the origins of JAMMA)
        (Noel Tominack)

9.3.10) The Williams Hardware File 
        (Rick Schieve, Gregg Woodcock)

9.3.11) The Cinematronics History File (technical overview and 
        design history of Cinematronics)
        (Steve Ozdemir)

9.3.12) Buying from an Operator FAQ 
        (Doug Jefferys, Steve Ozdemir)

9.3.13) R.G.V.A.C. FAQ 
        (Tony Jones)


 


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