Using Arcade Controls

If you do decide to use real arcade controls, you'll face
another choice: how do you connect these devices to your
computer? There are a few different methods you could try,
but perhaps the most popular and versatile method is to use
a keyboard encoder (also known as a key encoder). By default,
MAME maps each arcade control to a specific key on the
keyboard. Keyboards contain a circuit board. Wires connect
each key to a specific connector on the circuit board. When
you press a key, it completes a circuit and sends a signal to
the circuit board. The computer interprets the action as
a keystroke. Each key is really a switch.

That's the secret: you can replace these switches with other
switches. Most arcade controls are actually just switches.
Arcade joysticks are switches that move two, four or eight
directions. A button is a simple on/off switch. There are two
main kinds of switches for arcade controllers: leaf spring
switches and microswitches. Many arcade enthusiasts say that
the leaf spring design provides a better feel when playing
a game. Microswitches tend to have a clicky, stiffer feel.
But leaf spring switches are hard to find and require
maintenance more often than microswitches. If you decide to
go with leaf springs, be prepared to search around for
parts.

If you map each direction of the joystick to a different key
on the circuit board, you can program MAME to accept the
input . Some key encoder boards can accept input from
trackballs and spinners, and some MAME arcade machine
enthusiasts have built special encoders that they offer for
sale.

There are other ways to wire controls to a computer, too. You
might be able to pull out the circuit board from a computer
gamepad, wire your controls to the circuit board and map
everything out to the computer. But most MAME enthusiasts
prefer key encoders because they can handle more inputs.

Not all key encoders are created equal so it's wise to do
some research before purchasing one. Watch out for effects
like ghosting. Ghosting is when a key encoder sends a signal
for a specific keystroke even if you didn't push that
particular key. It usually happens when the key encoder
receives several signals in a very short burst. This can be
annoying when you're typing on a computer. But when you're
playing an arcade game, it could cause you to make
an unintentional suicidal jump or accidentally shoot that
princess you've been trying to save for 18 levels.