process control

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    LPT (parallel port) hardware question

    Hello. I am wanting to re-purpose an old laptop computer to use its parallel port (LPT printer port) to output a +5V/0V signal on one of the data pins. The load requires about 9 mA at 5V. I hooked up a data pin to a simple circuit with a variable resistance load, an ammeter, and a voltmeter...