Sharing Parallel Port


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Article ID: Q500003

The information in this article applies to:

  • Direct I/O, version 4.2, 4.3, 4.4

For Direct I/O, version 4.0, 4.1 see article Q500001.


Normally the parallel port (LPT) is controlled by the operating system. Software needing direct access to the parallel ports registers does not run properly.
Direct I/O can be configured to grab the parallel port resources and allow those programs to run successfully.


Follow the steps given below to configure your system properly:

  1. Open the Direct I/O Control Panel
  2. Identify the parallel port you want to use and enter the resources in the tab I/O Ports
    LPT1:   378-37A 378-37E 378-37F
    LPT2:   278-27A 278-27E 278-27F
  3. Enter the appropriate pathname of your process in the tab Security
  4. Check if your application utilizes the parallel port IRQ. If you are unsure skip this step.
    You can enter an IRQ later if your application failed to run because of a missing interrupt.
    LPT1:   7
    LPT2:   5
    If you are running Windows 2000 or Windows XP you have to configure IRQ usage too. Please read article Q700006 for further reference.
  5. Close the Control Panel

Please read article Q700007 for instructions how to determine the resources used by your operating system.

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Last modified: 2018-04-24.
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