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Microsoft KB Archive/172122

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Knowledge Base

Toshiba I586 Pro 230 MHz System and the National 307 Chip

Article ID: 172122

Article Last Modified on 11/1/2006


  • Microsoft Windows NT Server 4.0, Terminal Server Edition
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Standard Edition

This article was previously published under Q172122


Windows NT may not recognize the COM2 port on a Toshiba computer.


Some Intel motherboards included in Toshiba computers support COM2 as an infrared (IR) device. If the COM2 port is set in the BIOS to Infrared Data Access Mode, Windows NT does not recognize it. If COM2 is set as a serial port, Windows NT recognizes it and makes it available automatically.

Windows NT fails to recognize the National 307 chip on the Intel motherboard included in some Toshiba computers. During Detection, Windows NT runs the DoesPortExist() function that reads the serial port's line control register. The COM2 port test usually returns 0x00; however, the infrared port returns 0x5C. The COM2 port is not available because Windows NT writes this returned value to the wrong registers in the device.


Perform one of the following to resolve this problem:

  • Manually install the COM2 port.

    Please refer to the manufacturer's instructions for making changes to your CMOS settings.

    1. Before Windows NT is installed, start the CMOS setup routine on the Toshiba PC. From the CMOS settings, change the infrared (IR) port to COM:2. When you install Windows NT, it will properly install the COM:2 port.
    2. If Windows NT is already installed, ensure the CMOS is set to COM2: (see step 1), then perform the following steps:
      1. Click the Start button, point to Settings, and then click Control Panel.
      2. Double-click the Ports icon, select COM2:, and then click Settings. Click Advanced, and then from the Settings for COM2 Port dialog box, select 03f8 for the Base I/O Port Address and 4 for the Interrupt Request Line. Click OK.
  • To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

    152734 How to Obtain the Latest Windows NT 4.0 Service Pack


Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.

Keywords: kbhotfixserver kbqfe kbbug kbfix kbhardware kbhw kbwinnt400sp4fix KB172122