Windows NT Parallel Ports Do Not Use Interrupts

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If you have applications that run very slow due to large print jobs, you can reduce the thread priority of the port print function by adding the following registry entry:

WARNING: Using the Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

Windows NT 3.51

1. Start Registry Editor (Regedt32.exe) and locate the following key:
   

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print

2. Add the following value:
   
   

         Key:   PortThreadPriority
         Type:  REG_DWORD
         Value: Thread_Priority_Below_normal
   						

3. Quit Registry Editor.

NOTE: If you start OS/2 or MS-DOS, you still need to check for IRQ conflicts; the Windows NT port driver will not be used.

Windows NT 4.0

1. Start Registry Editor (Regedt32.exe), and locate the following key:
   

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print

2. Add or change the following value:
   
   

         Key:   PortThreadPriority
         Type:  REG_DWORD
         Value: -1
   						

3. Quit Registry Editor.

The default value in Windows NT 4.0 for PortThreadPriority is 0, which equals THREAD_PRIORITY_ NORMAL. The value for THREAD_PRIORITY_ABOVE_NORMAL is 1 and THREAD_PRIORITY_BELOW_NORMAL is -1.