Copying to LPT Port in MS-DOS Session Slow

• Microsoft Windows operating system versions 3.1, 3.11

SYMPTOMS

When you use the MS-DOS level COPY command to copy a file to an LPT port in a Windows 3.1 MS-DOS session, Windows appears to be completely frozen until the MS-DOS command has finished executing.

This delay only occurs in 386 enhanced mode. The error does not occur in Windows 3.0 or 3.1 running in standard mode.

WORKAROUND

To work around this problem, you can either

• Edit the SYSTEM.INI file, and add the following lines to the [386enh] section:

        ReflectDOSInt2A=ON
        TimerCriticalSection=0
  

  NOTE: If you are using a network that requires TimerCriticalSection= set to a higher value, then setting this to zero may adversely affect the running of MS-DOS applications.

  -or-

• Run Windows in standard mode.

MORE INFORMATION

Below are the definitions for the two SYSTEM.INI switches listed above. These definitions come from the SYSINI.WRI file that comes with the Microsoft Windows Resource Kit for operating system version 3.1.

ReflectDosInt2A=<Boolean>

Default: False

Purpose: Indicates whether Windows should consume or reflect DOS INT 2A signals. The default means Windows will consume these signals and therefore run more efficiently. Enable this setting if you are running memory-resident software that relies on detecting INT2A messages.

TimerCriticalSection=<milliseconds>

Default: 0

Purpose: Instructs Windows to go into a critical section around all timer interrupt code and specifies a timeout period (in milliseconds). Specifying a positive value causes only one virtual machine at a time to receive timer interrupts. Some networks and other global memory resident software may fail unless this setting is used. However, using this setting slows down performance and can make the system seem to stop for short periods of time.