Windows 3.11 Serial Port Configuration Tool

In Microsoft Windows 3.11, the tool used to configure serial communication parameters—specifically parity, stop bits, baud rate, data bits, and flow control—was the Ports applet located inside the Control Panel. This built-in utility allowed users to customize the behavior of standard communications ports (COM1 through COM4) to ensure compatibility with external hardware such as modems, serial mice, and serial printers.

Accessing the Ports Utility

To configure a serial port in Windows 3.11, users followed these steps:

  1. Open the Main program group from the Program Manager.
  2. Launch the Control Panel.
  3. Double-click the Ports icon.

Configuring Parity and Stop Bits

Once the Ports dialog box opened, a list of available COM ports was displayed. Selecting a port and clicking the Settings button opened the detailed configuration window containing the following serial communication parameters:

  • Baud Rate: The transmission speed, adjustable between values ranging from 110 up to 19,200 bits per second (or higher depending on system hardware and drivers).
  • Data Bits: The number of data bits transferred in each frame, typically set to 7 or 8.
  • Parity: The error-checking method used during transmission, configurable to None, Odd, Even, Mark, or Space.
  • Stop Bits: The duration of the stop signal at the end of each transmitted character, selectable as 1, 1.5, or 2.
  • Flow Control: Handshaking method options, selectable as Xon / Xoff, Hardware, or None.

Advanced Port Settings

Clicking the Advanced button within the Settings window allowed administrators to configure lower-level hardware parameters, such as the Base I/O Port Address and the Interrupt Request Line (IRQ). This was essential for resolving hardware conflicts when using COM3 and COM4 alongside COM1 and COM2.

Changes made through the Ports applet were saved directly to the system configuration files, primarily stored within the [COMx] entries of the SYSTEM.INI file.