[Trlog] Strange laptop LPT behavior

[Dave Hachadorian]

On Thu, 13 Mar 2003 08:03:15 -0600 George Fremin III <geoiii at kkn.net>
writes:

> 	Some computers do not have a pull-up resistor on the 
> parallel port
> 	inputs. It might be necessary to provide pull-ups to +5 
> Volts on the
> 	two inputs used by the paddle. This can be done by 
> connecting a 10K
> 	resistor from each paddle input to pin 14 on the parallel 
> port
> 	connector. Pin 14 is held at +5 volts and will pull the 
> inputs up to a
> 	high logic level when the paddle input is open.

You can also supply the +5 volts from an external supply.
This frees up pin 14 to be used as a relay control port.

Dave Hachadorian, K6LL
Yuma, AZ