Microsoft KB Archive/123992

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Basic Configurations for COM Ports in Windows 95

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Q123992

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The information in this article applies to:


 * Microsoft Windows 95

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SUMMARY
Windows 95 includes a set of "Basic Configurations" for communications (COM) ports. These configuration options make it easier for you to avoid hardware conflicts by letting you easily change the settings a COM port uses.

These Basic Configurations provide the following:


 * A default configuration for each COM port. You cannot change this default setting.
 * Additional configurations for each port that lets you edit the IRQ setting. These configurations do not let you change I/O addresses.
 * Additional configurations for each port that lets you edit both the IRQ and the I/O range.

MORE INFORMATION
Basic Configurations are determined by the following table:

  Basic Configuration  IRQ Setting   Editable? I/O Setting  Editable? -  0                    4           No        03F8-03FF        No   1                    4           Yes       03F8-03FF        No   2                    3           No        02F8-02FF        No   3                    3           Yes       02F8-02FF        No   4                    4           No        03E8-03EF        No   5                    4           Yes       03E8-03EF        No   6                    3           No        02E8-02EF        No   7                    3           Yes       02E8-02EF        No   8                Variable        Yes       Variable         Yes COM 1 defaults to Basic Configuration 0. The IRQ can be changed by selecting Basic Configuration 1.

COM 2 defaults to Basic Configuration 2. The IRQ can be changed by selecting Basic Configuration 3.

COM 3 defaults to Basic Configuration 4. The IRQ can be changed by selecting Basic Configuration 5.

COM 4 defaults to Basic Configuration 6. The IRQ can be changed by selecting Basic Configuration 7.

Basic Configuration 8 can be used to configure additional COM ports because it lets you change the IRQ and the I/O address.

Example
The following is a sample procedure for changing the IRQ for COM 1:


 * 1) Click the Start button on the taskbar.
 * 2) On the Settings menu, click Control Panel, then double-click the System icon.

NOTE: You can skip steps 1 and 2 if you use the right (secondary) mouse button to click the My Computer icon and then click Properties.
 * 1) Click the Device Manager tab, double-click Ports (COM & LPT), then double-click Communications Port (COM1).
 * 2) Click the Resources tab.

NOTE: COM 1 defaults to Basic Configuration 0, and the settings are according to the table above.
 * 1) Click the arrow next to the Setting Based On box, and click Basic Configuration 1.
 * 2) Under Resource Settings, double-click Interrupt Request (or IRQ), then click the up or down arrow to change the Value field setting.
 * 3) Click OK and restart Windows when you are prompted.

Keywords : kbhw

Issue type : kbinfo

Technology : kbWin95search kbWin95