Plus Hard Card Conflicts with Mouse Port if Set to IRQ 12 (84809)

The information in this article applies to:
    Microsoft Mouse driver for MS-DOS
    Microsoft Windows 98

This article was previously published under Q84809


The Plus Hard Card conflicts with a Microsoft Mouse connected to a PS/2 style port if the card is set to IRQ 12. The cards do not come set to IRQ 12 from the factory, but some of the Hard Cards are user- configurable. If this is the case, the Hard Card should be changed to another IRQ setting.

If the Hard Card is set to IRQ 12 and the Microsoft Mouse is connected to the PS/2 port, IRQ conflicts occur in Windows 3.0 and 3.1, as well as MS-DOS based applications that support the Microsoft Mouse. This is not a problem with the Microsoft Mouse, but rather a hardware configuration issue


PS/2 mouse ports use IRQ 12 to communicate with the central processor unit (CPU). The following Plus Hard Cards have the capability of using IRQ 12, which conflicts with a Microsoft Mouse using the PS/2 port.
   Hard Card II    (40 MB, 80 MB)
   Hard Card IIxl  (50 MB, 105 MB)
These drives are not set to IRQ 12 by default. If you set it to IRQ 12, and you subsequently purchase a Microsoft PS/2 style mouse, the Microsoft Mouse cannot work. The only workaround is to use the mouse on a serial port, or to change the IRQ settings on the card.

The product included here, Plus Hard Card, is manufactured by a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.

Modification Type: Major Last Reviewed: 10/3/2003
Keywords: KB84809