Microsoft Mouse Behaves Erratically on the PS/2 Port

• Microsoft Mouse Driver for MS-DOS, versions 7.x, 8.x, and 9.0

SUMMARY

If your Microsoft Mouse is on the PS/2 port of your machine and it functions erratically, it may be out of sync with the CPU. This information applies to PS/2-style versions of the Microsoft Mouse for MS-DOS systems.

MORE INFORMATION

If your Microsoft Mouse is plugged into the PS/2 port of your machine and it behaves erractically, for example, it opens boxes in Windows by itself, moves around the screen when you aren't touching it, is uncontrollable when you move it, and so on, the mouse may be out of sync with the CPU. To see if this is the problem, plug the Microsoft Mouse into the serial port of the machine or plug it into another machine. If it behaves correctly on the serial port, then there is either some conflict with the PS/2 port or the mouse is out of sync with the CPU.

The PS/2 port runs off the machine's BIOS. As a result, the system clock does not keep this port in sync with the CPU as it does the serial ports. Because of this, the information that the Microsoft Mouse sends through the PS/2 port may get disrupted, or out of sync. Since there is no clock interrupt to get the Microsoft Mouse back into sync, you must close the application and reinitialize the mouse.

If the above symptoms apply and the mouse works correctly through the serial port, then the PS/2 port may be out of sync. Microsoft Mouse version 8.1 or later is recommended for trying to correct this problem.

If there is another PS/2 machine available and it has a working Microsoft PS/2 style mouse on it, test the suspect Microsoft Mouse on this machine by turning off the machine, plugging in the suspect mouse and restarting the machine. If the Microsoft Mouse now behaves correctly, Microsoft Mouse driver version 8.1 or later may solve the problem. If it does not, then there may be a software conflict or a PS/2 port problem. If the Microsoft Mouse is still uncontrollable on this second machine but it works fine on the serial port, there may be a problem with the PS/2 adapter cable.