Microsoft KB Archive/276887

= Debugger Is Not Enabled on IBM ThinkPad Computer =

Article ID: 276887

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition

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This article was previously published under Q276887



SYMPTOMS
When you try to configure an IBM ThinkPad computer for a kernel debug session by using a null modem cable or external modem, the serial port that is required for a successful debug session is not available when the computer starts. Because of this, the debugger is not enabled.



CAUSE
This issue can occur because by default, the serial port on the IBM ThinkPad computer is software enabled and only becomes available after the Windows operating system has loaded.



RESOLUTION
To work around this issue and enable the serial port for a successful debug session, you must set the following options in the Basic Input/Output System (BIOS) Configuration menu on the IBM ThinkPad computer:
 * Set &quot;Serial Port A&quot; to Enabled, with IO Address 3F8, IRQ 4.
 * Set &quot;Modem for Legacy OS&quot; to Enabled, with IO Address 3E8, IRQ4

NOTE: This procedure disables plug and play.

For information about how to alter BIOS settings in your IBM ThinkPad computer, please view the documentation that is included with your computer, or contact IBM.



MORE INFORMATION
Note that the serial port is available after Windows starts, and you can then use it within the active Windows session.

