Learn about the technologies behind the Internet with The TCP/IP Guide!|
NOTE: Using robot software to mass-download the site degrades the server and is prohibited. See here for more.
Find The PC Guide helpful? Please consider a donation to The PC Guide Tip Jar. Visa/MC/Paypal accepted.
|View over 750 of my fine art photos any time for free at DesktopScenes.com!|
Free Up IRQ12 by Disabling the Built-in PS/2 Mouse Port and/or Moving to a Serial Mouse
Many newer PCs come with an integrated PS/2-style mouse port. Using this port allows you to conserve a serial port and serial port IRQ that would otherwise be used for your serial mouse. However, some people do not use their PS/2 mouse port; the most usual reason is upgrading from a previous system that didn't have one and not wanting to purchase a new PS/2 mouse. Also, in some rare cases IRQ12 might be needed more than the serial port's IRQ, so you may want to switch from PS/2 to a serial mouse.
Before you do anything, verify what type of mouse you are currently using. This is pretty easy to do; the simplest way is to check the connection to the PC; if the mouse is plugging into a small, round connector on the PC, you are already using a PS/2-style mouse (most of the larger retail brands use them). If the mouse is going to a 9-pin or 25-pin D-shaped connector, it is a serial mouse. You can also use the Windows 95 Device Manager or the Windows 3.x Setup program to see what sort of mouse is installed.
If you are already using a serial mouse on a system that includes a PS/2 mouse port, disabling the port is easy and will free up IRQ12. Go into the BIOS setup program and look for a BIOS parameter called something like "PS/2 Mouse Enable". Disable the parameter and the PS/2 mouse port will "disappear" from the operating system and its IRQ will be freed up as well.
If you are currently using a PS/2 mouse and want to move to a serial mouse, here's what you will have to do:
Warning: If you had any devices
that were using COM ports before you made this change, you may theoretically now have a
resource conflict, since the mouse will be using one of the ports. In particular, if you
already have two COM ports in use, I do not recommend eliminating the PS/2 mouse, as you
will have a problem finding enough low-numbered (2 to 7) IRQs for all the serial devices.