Don't know exactly what the board is used for, but I can say that 74221
chips are often used as "pulse-stretchers." That is, it takes an input
pulse and the output pulse is of a width that is dictated by a
resistor-capacitor combination. Each 74221 is made up of two separate
pulse-stretchers, so this board effectively has six channels. Perhaps in
the past a different game board was used inside the cabinet and input
signals were "stretched" to give the computer more time to time to recognize
joystick or coin switch commands. Wild guess...
Matt J. McCullar
Arlington, TX
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Received on Fri Dec 14 17:19:54 2001
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