Hi,

You can use a built-in feature of Windows if the PC has an unused serial port.
This feature lets you send any kind of keystroke to the PC via serial port.

* * *

Use an Alternative Input Device Instead of a Keyboard or Mouse

SerialKeys is accessibility feature designed for people who have difficulty
using the computer's standard keyboard or mouse. SerialKeys provides support
so that alternative input devices, such as single switch or puff and sip
devices can be plugged into the computer's serial port.

https://www.microsoft.com/windowsxp/...erialkeys.mspx

How to Set Up and Use SerialKeys in Windows:
http://support.microsoft.com/?kbid=260517

Best regards,

Luciano