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JUMP Interface Specifications
I. How NES/SNES controllers work
I. How NES/SNES controllers work If you take a look at a Nintendo / Super Nintendo controller you'll notice it has 8 to 12 buttons (including Up, Down, Left, & Right) but it only has 7 connector pins. Even stranger is the fact that it actually only uses 5 of the pins to operate. You may find yourself asking "How on earth can 5 pins carry enough information for 12 buttons?" Well you've come to right planet to find out... Most modern gamepads use a serial transfer mode to send data to the game console. A clock wire and a latch wire run from the console to the controller. The clock line is turned on and off repeatedly. Every time it's reactivated, the controller sends the status of another button on the data wire. For one of the better explanations, check out the linux faq.
The parallel port adapter cooperates with the drivers so the gamepad thinks it is connected to a console and so the computer understands what the gamepad is saying. Every gamepad requires a power line, ground line, clock line, latch line, and a data line. If you have multiple controllers connected, they can share every connection except the data line. Since 25 pins run from the parallel port you would expect to be able to connect a LARGE number of controllers. Unfortunately, serial gamepads require power and parallel ports don't have a power line that the controllers can tap directly from. The drivers were designed to keep a steady line current going through several of the pins which allows the controller to still get the power it needs from the parallel port. Bear in mind that there are many types of controllers and many more types of parallel port circuits inside modern computers too. If your controller is power hungry and your parallel port is older and does not supply much power, then you may need to find an alternate way to supplement your specific power needs. Take a look at the linux joystick info sheet for some ideas on how to grab more power. Putting all this together, the parallel port drivers have single pins set aside for clock and latch, 6 pins to supply enough power to the controllers, 2 for ground, and 5 are individual data pins (and therefore the maximum number of NES/SNES gamepads you can connect to the parallel port interface without rewriting the drivers yourself. The adapter does not require any advanced circuitry because all it does is connect a wire on the controller to a wire on the parallel port. It is highly recommended that you attach diodes to the power pins to protect your controller (as illustrated in all of the plans).
The JUMP Interface does not change the drivers or the wiring of the adapter at all. Instead pf permanently attaching the adapter wiring to the the end of the joystick cable, JUMP separates the adapter portion into a separate box and uses simple modifications to the joystick to make them work with the interface. In other words, most of the other designs on the internet have you permanently mangle your controllers in a way that they can ONLY be used on your computer and you have to rebuild the interface for EVERY controller you want to use. You can get around this IF you can get your hands on an extension cable that will work with that controller and modify it. But let's face it, I haven't seen a set of NES extension cables in years so this is hardly a viable option. Instead of permanently wiring each controller to plug directly to your PC, JUMP uses an interface box to house the "circuitry." By making simple modifications to the controllers, you connect the controllers, to the interface and the interface to the PC. the modular design is much more efficient and of course, interfaces are just cool and impressive looking.
For basic info about the circuit wiring, design, and the JUMP connection protocols, check out the Basics page.
Since the wiring for the adapter is very simple, I've tried to keep the instructions simple as well. They include a wiring diagram plus some comments for each specific version of the interface. If you plan on using NES controllers with your interface, you'll want to read about its special power needs and see the solution we like to use. Single-port
JUMP Mini-Interface
Modifying your controllers to work with the JUMP interface is easier than you might think. Follow the instructions on the following link to upgrade your controller in about 30 minutes.
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