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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
- WWW version by Frederic
Vecoven (veco@montefiore.ulg.ac.be)
-
- 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.
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.
Since games are what it's all about, let's take a typical video game
and slice it up into its principal components:
- 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.
- 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.
- 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!
- 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.
- 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.
- 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.
- 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.
- 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)
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.
- 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
- 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...)
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!
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.
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 stormaster.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.
So you've just compared two sets of pinouts and seen that they're
basically the same. You plug the new board in, power things up,
and everything works fine until you try and start a game. You
then remember that the controls are different.
Bummer, eh?
Well, not really. 90% of the work has already been done; the
game is up and running, so the rest is just a matter of wiring.
As an example, we'll take Gravitar and Space Duel. These boards
have identical pinouts for power, sound, and video, so you can
just "plug-n-chug" to power things up. As the control panel
portions of the games' pinouts differ, you've still got a little
more work to do before you've finished the conversion.
(In case you're wondering why the panels were made incompatible,
Atari didn't want to make it too easy for operators to have
their cabinets playing different games -- this was before JAMMA,
back in the Golde^H^H^H^H^HDark Ages when each game came in its
own cabinet, with its own artwork, marquee, and control panel.)
What this means is that if you're trying to put a Gravitar board
in a Space Duel cabinet, you'll need to rewire it using a switch
with six poles -- to swap the six signals going to the panel,
depending on which game you're playing. The end result should
look something like this:
PCB Space Duel controls Corresponding button on Space
pin wiring harness pin Duel panel for SD or Gravitar
_________P2 Rot R (for playing SD)
19-E_______Pin 3_________/
\_________P1 Rot L (for playing Grav)
_________P2 Thrust (for playing SD)
20-M_______Pin 4_________/
\_________Select Sw (for playing Grav)
_________P2 Fire (for playing SD)
19-4_______Pin 5_________/
\_________P1 Fire (for playing Grav)
_________Select Sw (for playing SD)
20-11______Pin 7_________/
\_________Start Sw (for playing Grav)
_________P1 Fire (for playing SD)
19-3_______Pin 11________/
\_________P1 Shields (for playing Grav)
_________Start SW (for playing SD)
19-6_______Pin 14________/
\_________P1 Thrust (for playing Grav)
The rest of the control panel inputs don't matter since they are
either the same (i.e. both games use the same PCB pin for the
button/game function) or left unused by Gravitar.
The other option, if you don't have a six-pole switch handy, but
you *do* have a Gravitar control panel handy (remember we talked
about "resources" earlier?) is to simply swap panels. Rig up an
adaptor to go between the Gravitar control panel and the rest of
the Space Duel wiring harness. As you're only interested in the
control panel inputs, this can often be a convenient "shortcut"
around the adaptor hackery route which we'll be discussing next.
This was all about adding a Gravitar board to a Space Duel
cabinet. Going the other way with a simple control panel swap
is much more difficult, owing to the larger number of inputs
required by Space Duel. These difficulties will be discussed
in more detail in the next section.
For all practical purposes, hacking or swapping control panels
is really just a sidetrack from the types of conversions
available; it's something done to facilitate a conversion,
rather than being a conversion in and of itself. At the end of
our discussion on control panel hackery, we mentioned that one
could construct an adaptor that would go between the new control
panel and the old wiring harness. Since you have to swap both
the board *and* the control panel, and since these two parts
are normally located fairly far away from each other in most
cabinets, why not move the adaptor to the other end of the
wiring harness? There are times when it's much easier to
simply place the adaptor with the new board itself.
Such adaptors are the next-simplest form of conversion. They're
what you usually build when your new board doesn't match the
wiring harness of the game you're trying to play it in. They
take a little time and effort to build, but are almost always
worth it. Experienced collectors will often accumulate large
"libraries" of adaptors to use with their games.
To build an adaptor, you'll need accurate pinouts for both your
wiring harness and for the board set(s) you're trying to plug
into it. Of course, if the pinouts match, you've got a
"plug-n-chug" situation, and no adaptor is required.
If not, however, you might consider modifying the board to suit
the harness. This is generally a *bad* idea; you'd like to keep
the board as intact as possible, if for no other reason than
you'd like to be able to trade it with a friend someday, or send
it off somewhere to have it fixed. Moreover, cutting leads and
soldering wires directly to a board may also damage it, create
unreliable solder connections, and may also make debugging your
work more difficult. On the other hand, adaptors require parts,
and if you're *really* desperate for parts, you may have no
choice but to modify the board directly, even if you may regret
it later.
Rather than modify the board directly, most people build an
adaptor to stick on the end of the board. This is a little
device composed of some connectors and wire, and it maps the
board's pinout to that of the wiring 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.
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? :-)
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.
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.
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.
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.
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.
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.
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.
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.
So, your conversion doesn't work. Bummer, and welcome to the club.
This section isn't intended to be a complete guide, but it should
serve as a useful checklist for your first stab at making things
work. You should also probably check the "Miscellaneous tips"
section, as it's got some random tidbits of information that may
also prove useful as you try and understand what went wrong.
- Before you power up, check your wiring. Pay extremely close
attention to your power and ground connections; checking them
more than once is perfectly fine. On valuable boards, one of
our authors has been known to check three times -- anything
less than a unanimous "yes, it's perfect", and the power switch
doesn't go on.
- After you power up and it doesn't work, check your wiring.
It's amazing how many times you can look at a piece of wire
and say "yup, it's in the right place", and still be wrong.
Trust us on this one.
- Also check your wiring against "standard" documentation, and
if that doesn't work, check it against the hardware itself.
You may be doing everything "right" according to the document
you found on the 'net, but a look at the schematics will
highlight an error. This may come as a shock to some, but
there have been real incidents in which stuff posted to USENET
did, in fact, contain errors. Film at 11.
Conversely, you may be developing a conversion from scratch, and
you'll find errors in the official manufacturer's schematics.
These are rare, but they're out there. If there's any doubt,
check the hardware itself. Silicon doesn't lie.
A word on manuals -- there's no "library" of manuals out there,
nor will there be. Most manufacturers stop supplying manuals
for their games after a few years (Atari is the lone exception;
$14 will get you a copy of any manual they've ever made), so the
only real sources of docs are whatever you can find when you're
out buying, or the archives of other collectors on
r.g.v.a.c.
Playing librarian isn't a whole lot of fun, but a cheque for
$20 or so will still convince most collectors (at least in 1994)
to dig through their files and find a copier. Still, it does
take time, so if you're working with Atari parts, we recommend
you deal with them -- (while there's sometimes a risk that the
schematics will be photo-reduced beyond the point of legibility,
they've also been known to send original copies if they have a
large enough inventory. Ya pays your money and ya takes your
chances, but the service is still infinitely better than that
offered by other companies...)
- Regression-test. If you're at a stage where you think that part
(even if not all) of the conversion will work, power it up and
see what happens. If it works, you've at least got something
you can go back to. For instance, when creating a JAMMA adaptor
for a game, hook up power and video outputs -- this will tell
you whether the game works or not. Once you've got this
working, you can worry about sound output and control panel
inputs.
Be careful when regression-testing. If your adaptor doesn't
work, and you suspect it may have damaged the board in the
process, check the power supply before continuing. If the
power supply is damaged, it may also damage any *new* boards
you plug into it. The point here is to verify that *all* parts
of your system are still in working order before continuing any
further.
- Go backwards. If things stop working, go back to the last point
at which things worked, and see if you can't figure out where
you might have goofed.
- Check your assumptions. If you're doing a banking-style
conversion and things work for one game (but not another), maybe
you misread something on the schematics. Sometimes different
games will use the same hardware in different ways; Robotron is
an example of a game for which a simplistic address-decoding
scheme will work fine, but the same scheme will fail on Joust
and Stargate. The assumptions you make for one game may not
hold true for others, even if the underlying hardware is
practically identical. Diagnostic output from the game's
self-test routines can be very useful here.
- Buttons:
- Buttons are generally grounded on one side, so that the PCB
will see the input pulled low when the button is pressed.
- Leaf switches and microswitches:
- There are two kinds of switches: leaf switches and micro-
switches. For most applications, they're interchangeable.
Leaf switches have no "clicking" sound when pressed and were
common on old games; the newer microswitches make a definite
"click" when pressed and are more common on newer games.
Microswitches are more reliable than leaf switches, and
also provide a "normally-closed" output (the inverse of the
"normal" operation of a leaf switch or microswitch). This
output can be put to use as described later.
For normal applications, it doesn't make any difference which
kind of switch you use. Some players prefer one over the
other; it's this author's experience that one can develop a
faster "touch" on a leaf switch (useful for something like
Defender), but you lose something in terms of definitive
feedback (which would be valuable on a game like Street
Fighter).
- Digital joysticks:
- Digital joysticks are the same as four buttons; instead of
pressing buttons with your finger, you press them with the
stick.
- Analog joysticks:
- Analog joysticks are most often potentiometers and springs.
The "flight yoke" controllers for Star Wars, Firefox, and
STUN Runner, for instance, are all based on 5K pots. Other
examples of this type are the analog "thrust control" for
Lunar Lander and the steering wheel in Spy Hunter.
- Optical joysticks:
- The funky "optical joystick" used by Sinistar is a piece of
engineering artwork. It's also very rare, and even when it
can be found, it's usually very expensive.
It can also be replaced with a conventional (microswitch-
based) joystick. Note that it must be a microswitch-based
stick to work, as it relies on the use of the "normally-
closed" outputs that only a microswitch can provide.
See reference {9.2.1}
for more information on Lee Crawford's
Sinistar Joystick hack. At $8.00 and some wire, versus
$130.00 and a few weeks' wait for mail-order, you might
want to give it a try.
- Hall-effect joysticks:
- These are exotic creatures. If you find any at a bulk buy,
and you can get 'em cheap, go for it. They're generally very
hard to come by, and can be expensive if you try to purchase
directly from the 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.
- 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.
- 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.
- 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.
- Switching versus linear:
- A linear power supply has a large transformer that takes the
120V AC signal from the wall and converts it to a lower AC
voltage. It passes this lower voltage through a rectifier,
which will give you DC. The DC won't be flat or steady, but
at least you're halfway there. The DC is then passed through
a filter to smooth it out, and then a voltage regulator to
obtain the exact voltage.
All of these steps, when taken together, require a lot of
power; you're effectively converting excess energy into heat.
The transformers tend to be extremely bulky, and more often
than not, rather expensive.
Whenever possible, use a switching power supply. They're not
only cheaper and lighter than their old linear counterparts,
they're also more reliable and produce a cleaner supply for
your game. Can't find one cheaply? Rip apart an old IBM PC
and use its power supply. It will supply everything you need
for running the average board.
- Hacking boards with weird power requirements:
- It's often a good idea to modify a board with strange power
requirements or a strange sync, so that you can use your
existing switching power supply and/or monitor. Don't modify
the cabinet - modify the board since it makes future
conversions/board swaps easier. Yes, this goes against our
earlier advice of being nice to your boards, so let's just
say it's a judgement call. It depends on your taste, your
ability, and the odds that you might want to sell or trade
the board away in the future.
If you're dealing with weird power requirements as in, say,
Pacman boards, which convert 7.5V AC; (yes, Seven-and-a-half
Volts of Alternating Current, which gets stepped down from a
linear power supply earlier in the cabinet -- see what we mean
about linear power supplies being potential pains in the butt?)
into +5V DC on the board, you're pretty safe to modify the
board, as you won't be seeing many situations where 7.5V AC
is supplied.
If it comes time to sell the board, you'll have a much
easier time making the sale if it can use "standard" power
requirements. In the case of Pacman, the modification (which
involves only five jumpers) is also easily reversible, which
is a bonus, just in case you should be selling it to someone
with an original Pacman cabinet someday.
If, on the other hand, you're just dealing with something like
pins in different places, but normal voltages, it's probably
best to build an external adaptor and include it between the
board and the wiring harness. This way, you don't run the
risk of damaging the board by making a mistake, and a future
buyer of your board won't have to "unfix" it at a later date.
Meanwhile, the Pacman modification is as follows:
- 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.
- Jumper a fifth wire across the large 4-ohm resistor by the
heat sink.
- Pacman's 7.5V AC pin gets connected to +5V DC from the
power supply.
- Pacman's GND pin (from the center tap of the 7.5V AC
signal) gets connected to GND from the power supply.
- Pacman's 12V AC pin gets connected to +12 V DC from the
power supply.
- 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.
- NOTES:
- If you are applying a voltage to a board that's not
specified in the manual as the correct voltage, then
you *are* taking a risk that might fry your board.
Be *VERY* careful as you try to substitute different
voltages/circuits in an attempt to avoid using an
oddball voltage, and make sure you understand (using
the schematics and your knowledge of electronics)
what the board is trying to do with that oddball
voltage before you start.
Another example of applying a little understanding to a
problem would be the Pacman modification discussed above.
Elsewhere on the board, a 12V AC signal is used to generate
+16V DC for the audio circuitry. A look at the schematic
reveals that the audio op-amps are the only place where the
+16V DC is used, and a databook tells you that the chips in
question can also be powered with +12V DC. Since you *know*
what the board wants and what it can handle, you can use this
to design your workaround. This is part of the reason why the
hack to Pacman discussed above allows you to get away without
using the original Midway power supply.
In an interesting twist of fate, and an example of how various
manufacturers "borrowed" from each other during the industry's
early days, note that Sega's "Super Moon Cresta" uses exactly
the same power scheme as does Midway's "Pacman". Same hack to
convert to DC, same power and video pins, same bloody *PARTS*
in the same *LOCATIONS* on the board, etc... So if you get a
sense of deja vu when hacking on an old board, don't ignore
it. You probably *have* seen it before.
- Geographical considerations:
- In North America, the power that comes out of your wall socket
is 120V AC. This assumption does *not* hold true for Europe,
where 240V AC is the norm.
Some power supplies have little switches on them to switch
between 120V AC and 240V AC inputs. Others (Atari linear
power supplies in particular) have "voltage selection plugs"
that can be used for the same purpose.
If you don't know what type of power your power supply
expects, and especially if you've received parts from
overseas, take a few minutes to check.
- Horizontal versus vertical:
- Don't bother rotating a monitor from vertical to horizontal
(or vice versa). Just buy another cabinet with a monitor
oriented the correct way. You'll save yourself a lot of
headaches (and back pain) in the long run.
There are two exceptions to this rule: Sega's "convert-a-
cabinet" system (used on their vector games) included slots
to allow the monitor to be removed and rotated easily, and
some of the new higher-end JAMMA cabinets, which have a
swivelling monitor which can be rotated from horizontal to
vertical without having to remove it.
Actually, there's one other exception. Don't use a cabinet!
If you're not worried about appearance, your setup can be as
simple as a power supply, harness, joystick, and monitor on
a workbench. Rotating the monitor in this kind of a situation
is a piece of cake :-)
- Swapping outputs to rotate:
- It's possible to avoid the problem of rotating monitors with
vector games; you can put the vertically-oriented Tempest in
any other Atari color vector cabinet, which will be
horizontally-oriented. You can sometimes swap the X and Y
outputs on the Tempest board and shrink the dimensions with
the adjustments on the game board to get it playing on a
horizontally mounted monitor. Some monitors (and some
Tempests :-) seem to cooperate, and some won't. Give it a
try and see what comes 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.
- 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.
- 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
----------------------------------------------------------
- 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
------------------------------------------------------
- Identifying pinouts:
- Identifying pinouts of unknown boards can be difficult.
We offer the following approach:
- 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...)
- 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?
- 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.
- Okay, now you're desperate :-) Get a list of all the
pinouts that you *DO* know.
- Eliminate any pinouts with connectors that don't match
the board in question.
- 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.
- 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.
- *NOW* do you have a match? If so, start "experimenting";
make a few assumptions and try powering the board up
without any video or controls connected and "experiment"
by looking for fluctuating signals (characteristic of video
or audio) on the pins. This is a fairly involved process,
but can be simplified greatly by use of a partially-
constructed adaptor to your current wiring harness.
(Indeed, this is one of the reasons adaptors are fairly
popular; they often get created through the process of
determining the pinout from an otherwise unknown board)
Note that this can be something of a risky procedure if you
don't know what you're doing. For your first few times,
you may want to do everything except powering up the board:
write down your best guesses, describe the board, and ask
the 'net if anyone out there recognizes it and knows the
pinouts. You might just get lucky, and if your guesses
were right, you'll give your self-confidence a great boost.
Rick Schieve has written an excellent text file on this
subject; see reference {9.3.4}
for details. John Keay has
another method for quickly identifying and recording pinout
information; see reference {9.3.5}
for details.
- Unused connectors:
- If there are empty connectors on the board, don't panic. Some
boards have "test connectors" that are unused during normal
use. If you don't know whether a certain board or board set
is complete, ask the 'net if anyone knows "how many boards
and connectors were used in XYZ".
- 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".
- 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.
- 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...
- 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.
- The Basics:
- Rick Schieve has written a text file on raster video basics;
check out reference {9.3.6}
(Raster Monitors) in the bibliography
for more information, but we'll summarize the high points here:
All raster monitors use generally the same set of inputs:
RGB, and some form of sync. RGB stands for "Red, Green, and
Blue", and denotes the colors of the beams. Sync is for
"synchronization", the process by which the electron beam in
a raster monitor sweeps across the screen.
(You may have heard the terms "horizontal", "vertical", and
"composite" sync. For now, just consider "horizontal" sync to
be the sync pulse at the end of each line on the screen, the
"vertical" sync to be the pulse at the end of each screenful
of data, and "composite" sync to be a magical combination of
both. We'll get into the gory details soon enough :-)
So far, so good, right?
Wrong. While all these signals are common to raster games,
they come in different (and alas, incompatible) flavors.
Working around these difficulties can be one of the more
confusing problems for someone doing conversions. That's
where this FAQ comes in. We'll try and describe the common
variants, and give a few examples of games that use them.
You should be able to extend the approach to other games.
- RGB polarity
- While all raster monitors accept RGB inputs, they can have
either positive or negative logic. The majority of games use
positive logic (when the voltage is on, the electron gun turns
on, and you get a bright image), but Nintendo games use
negative logic, which works the other way around.
RGB signals are analog signals; you'll need an analog inverter
to get around the problem; a CMOS hex inverter (say, a 4069),
which is designed to invert digital signals, won't work. To
be more precise, it theoretically *shouldn't* work, but on
the practical side, a few people have tried it and actually
managed to make it work. Your mileage may vary. One tip: if
you try this, make sure you ground all of your unused inputs.
Meanwhile, the "right way" is to use an analog inversion
circuit for each of the three RGB signals. It requires a
+12V, -12V, and -5V supply, but some power supplies will
supply all three voltages. Thanks to Paul Kahler for the
original schematic and document (see reference
{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.
- Sync polarity:
- Now that we can generate the RGB signals our monitor requires,
we still have to put the signals on the screen in an orderly
fashion. The is what the "sync" signals are for.
Again, we run into the problem that some boards produce
negative sync, and some don't. Fortunately, since all sync
signals are digital, the process is much simpler; using a
*really* fast CMOS hex inverter is a perfectly legitimate way
around the problem. A TTL inverter should also work; all sync
signals generally operate at TTL levels. Still, this is dicey
business, so your mileage may still vary.
- Composite versus Separate Sync:
- Now that you know how to invert syncs, you're ready for the
last bit - the two flavors of syncs and how to mix and match
them.
Older monitors often had separate sync inputs; one for
horizontal sync (the retracing of the beam across the screen),
and one for vertical sync (the return of the beam from the
bottom of the screen to the top of the screen).
Newer games (but also many older ones) used monitors which
accepted composite sync; the two signals were combined together
on the board, and a bit of circuitry in the monitor determines
whether a given sync pulse is a horizontal or vertical retrace.
If you have an older game that outputs separate syncs, and
a newer monitor that can only accept composite sync, you can
combine the two using digital logic. Simply "OR" the two
signals together with a TTL chip to obtain the composite sync
signal.
Since both composite and separate syncs can be positive or
negative, it may be necessary to invert the composite sync
signal after the ORing stage. If this is the case, just
use a NOR gate instead.
- Sync shortcuts:
- If you've got schematics for your games, take a closer look
at them. The game's wiring harness may show separate syncs,
but the schematic itself may show that there are unused pins
for composite sync. All the old Williams games (Defender,
Stargate, Joust, Robotron, etc...) are like this, as is
Atari's Missile Command.
A little schematic-browsing can make your life much easier.
One last cheat -- if your monitor only supports separate
sync, you may be able to get away with connecting a composite
sync signal to either the horizontal input or to both inputs.
No guarantees, but you might as well try it as a "first shot".
- Smoke and mirrors:
- Some games have mirrors in the cabinets which reflect the
video output. This is great, if you're playing Asteroids
Deluxe in the original cabinet. This sucks, however, if
you're trying to put an Asteroids Deluxe boards in a
conventional Asteroids cabinet. Most of these games have pins
on their edge connectors for X- and Y-inversion; pulling these
pins high (+5V) or low (GND) will invert the image in the
appropriate axis. Play around until you've got something
that looks right on your screen.
- Cocktails, anyone?
- To further complicate things, some games have "cocktail" pins,
which are pulled high or low depending on the wiring harness.
On upright games, the signal on the "cocktail" pin tells the
game *not* to invert the image when player 2 is up. On
cocktail machines, the signal tells the game *to* invert
player 2's image.
Finally, and this is the *really* weird one, some games use
both approaches -- a PLAYER1 and a PLAYER2 pin, for instance,
were used on the Asteroids cocktail machine, both to activate
and de-activate the two players' control panels, but also to
control video inversion.
Our point here is not to confuse - merely to say that if the
game appears upside-down or backwards for no apparent reason,
you should probably take a closer look at the pinouts. It's
amazing the number of variations that are out there, and it's
sometimes a miracle that things show up correctly at all!
Again, our earlier rule of thumb applies: If you don't like
what you see, play with it until you do.
As a last shot - sometimes it's not on the pins at all. More
recent games control their "cocktail" versus "upright" behavior
by means of a DIP switch setting. Fiddle with these if you
think you've tried *everything*...
- 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.
- 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.
- 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 :-)
- 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.
- 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.
- 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:
- Completely strip the front panel and remove it. This
may also involve removing bits and pieces of the old
plastic artwork that covered it.
- 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.
- 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.
- 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.
- 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.
- 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.
- Solder the leads to the controls, and you're done.
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
stormaster.com FTP site.
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
stormaster.com;
please check there first before requesting a copy from the authors.
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