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I/O module driven by a computer parallel port

With this unit a regular computer parallel (printer) port will give you 5 inputs and 8 outputs to use for something fun. And it’s very simply to build; one transistor and one resistor per output, and a single resistor for each inputs. The parallel port is pretty easy to access in most programming languages. The module as a 36 pin centronics connector, making it easy to connect to the computer using a regular printer cable.


LCD unit driven by a computer parallel port

This very simple module is driven purely by a computer parallel (printer) port. Almost no external components are needed; a few capacitors for voltage stabilization, a trimmer for the contrast adjustment and a resistor for the LED back-light. All communication is done directly over the parallel port data lines. The LCD is powered by an external 5 V power supply. It can’t be placed too far from the computer though since the recommended max length of a parallel cable is 15 ft.