ELECTRICAL SPECIFICATIONS AND INTERFACING
The joypad is available in both digital and analog form.
The standard digital joypad has a four bit bus structure with a single strobe line (strobe high or low) for a total of five lines. The pad presents approximately 30 pf of input capacitance to the strobe line and is guaranteed to have no more than 75 ohm closed resistence after one million operations (average resistence is 5 ohms). Therefore, two digital joypads may be connected to a standard 8 bit microprocessor bus with the strobes on the address bus without loading most common MOS microprocessors. Obviously, the digital joypad may also be used as a simple switch closure in other logic systems. The maximum source current from the device is 100 milliamperes.
The analog joypad, like the digital device, is not restricted in its application. For instance, the analog joypad is available without cover or wiper so that it may be used with other mechanical wipers in process control or as a guide feedback circuit for precision plotters etc. Let me stress that the analog joypad is nothing more than a homogeneous resistence which has been linearized to two orthogonal connections and that therefore it may be used in any manner that the fertile mind of an engineer might conjure for a device with its electrical and mechanical properties. It is not even necessary to mechanically wipe the joypad in order to use it.
The clear joypad is nothing more than the standard joypad with a transparent homogeneous resistence and a layer of dielectric protecting the resistence. Position is coupled out of the device capacitively and translated as either amplitude (the amplitude of the derivative of the impressed voltage) or phase information. The capacitive coupling may be by probe or a finger used as a probe. The dielectric used in the clear joypad is washable and scratch resistent while the total pad thickness is approximately .050 inch which minimizes location
Black Jack is offered on a Fairchild Video Entertainment System cartridge.
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