Parallel Port Monitor
parallel.exe port monitor program.

Parallel Port Monitoring Program

To run this program, just invoke 'parallel' from the DOS prompt. The default will be to monitor LPT1. You can specify '1' or '2' as an optional argument on the command line to specify which LPT port to monitor.

This program monitors and controls the bits on any parallel port. (This program predates the advent of bi-directional parallel ports, so only suports them in unidirectional mode)

Supply either a '1' or a '2' on the command line to specify LPT1 or LPT2, eg. "parallel 2" to monitor LPT2.

Lines in BOLD are "input" signals, other lines are either "output" signals, or unused ground pins.

The STATE column monitors the realtime input and output bit states on the port; 'SET' if the bit is set, 'clr' if the bit is clear.

You can use the up/down arrow keys to move the inverse "cursor" (the white block) to focus on a particular signal:

All the input pins (10,11,12,13 and 15) each have scrolling 'oscilloscope' that runs along the bottom of the screen to show the set/clear state. The scrolling aspect allows one to more easily oscillations on the input.

Hit ESC to exit this program.

The parallel.exe program should be part of your OPCS installation. If it's not, you can download it from

© Copyright 1997, Greg Ercolano. All rights reserved. To report documentation errors, send email to