Parallel ports are somewhat "robust". I "think" the data lines have series
resistors to prevent shorts in the printer cables from destroying the pio
drivers. Since some port lines are bi-directional, you can't really buffer
them. If you want to be really protective, you could install an interface that
would have each data line strapped with diodes to prevent voltages over +5
volts and under 0 volts from destroying your pio chip. Cathode to +5, anode to
data, and another cathode to data, anode to ground. Do this on all data and
printer status lines. This will also supress "some" static electricity from
eating up your pio chip. I believe +5 volts is on the db25 too.

Rick

Tal Bejerano - AMC wrote:

> Hello 2 All
>
> I want to do some experiments with my pc parallel port.
> How can I protect it in the easy way not to burn it if I do any mistake or
> short circuit?
>
> Thanks
>
> Tal
>
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