Microsoft KB Archive/132500

Money 3.0:Second Online Session Hangs Computer with Ext. Modem

PSS ID Number: Q132500 Article last modified on 12-12-1997

3.00 3.00a

WINDOWS

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= SYMPTOMS =

You are unable to connect to Online Services a second time during a single Windows session, even though you had no trouble connecting the first time. Your computer stops responding (hangs) and must be restarted.

= CAUSE =

A problem with a Super I/O chip (SMC665) can cause this behavior. This chip is generally used for the serial port on many new (usually PCI bus-based) computers. This problem is dependent on the UART (Universal Asynchronous Receiver Transmitter) chip used for serial port; the type of bus doesn’t matter.

The system stops responding if the buffer contains data when the serial communications application attempts to open the communications port. A problem with the chip implementation traps the chip in a mode where data is always detected in its FIFO (First in First out) buffer.

Because the problem is related to the computer’s serial port UART chip, this problem occurs with external modems only. Internal modems use their own UART chip.

= RESOLUTION =

Use the resolution below appropriate for the version of Windows installed on your computer.

Windows for Workgroups
To correct this problem in a Windows for Workgroups 3.11 environment, obtain the updated SERIAL.386 driver included with PSS Application Note WG1001: Updated SERIAL.386 Driver for Windows for Workgroups.

NOTE: If you do not have access to an updated driver, try the Windows 3.1 solution.

Windows 3.1
If you are using Windows 3.1, you can disable the FIFO buffer by editing the COMxFIFO key of the [386Enh] section in the SYSTEM.INI file, where x is the number of your COM port. For more information about how to perform this task in Windows, see your Windows printed documentation or online Help.

NOTE: Add the entry if it does not exist.

For example, the FIFO for COM2 can be disabled with the following entry:

[386Enh] COM2FIFO=0

NOTE: Disabling a COM port FIFO buffer reduces its data throughput.

Windows 95
To disable the FIFO buffer in Windows 95, do the following:

  Click Start, point to Settings, then click Control Panel.   Double-click System.   On the Device Manager tab, double-click Ports (COM & LPT).   Double-click the communications port (COMx) you want to change.   On the Port Settings tab, click Advanced.   To disable the FIFO buffer for a 16550 UART chip, make sure the Use FIFO Buffers (Requires 16550 Compatible UART) check box is cleared. NOTE: The COMxFIFO setting that can be manually added to the [386Enh] section of the SYSTEM.INI file does not affect Windows-based programs in Windows 95. This setting affects only MS-DOS-based programs. 

For additional information about this issue or for information about disabling the FIFO buffer, please see the following article(s) in the Microsoft Knowledge Base:

ARTICLE-ID: Q110568 TITLE : Pentium-Based Machine Hangs with Communication Applications

ARTICLE-ID: Q112300 TITLE : WG1001: Updated SERIAL.386 Driver for WFWG

ARTICLE-ID: Q119853 TITLE : PC Hangs While Running a Communications Application

ARTICLE-ID: Q131016 TITLE : Win95x: Settings for the 16550 UART FIFO Buffer

The third-party products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products’ performance or reliability.

Additional query words:

KBCategory: kb3rdparty kbprint kbenv kbhw kbprb KBSubcategory: kbonline

Additional query words: 3.00 3.00a hangs hanging hanged crashed crash gateway2000 exit restarted gateway Dell PS AMI motherboard kit machine built-in com comm port ports w_money crashes freeze frozen locked locked-up lock hang hanged bombed bomb down p.c.i buss chipset online service communicate communication com

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========================================================= Keywords : kbonline Version : 3.00 3.00a Platform : WINDOWS ============================================================================= Copyright Microsoft Corporation 1997.