Writing Interrupts (ISRs) That Call Mouse Functions (46462)

The information in this article applies to:
    Microsoft Mouse driver for MS-DOS 6.x
    Microsoft Mouse driver for MS-DOS 7.x
    Microsoft Mouse driver for MS-DOS 8.x
    Microsoft Mouse driver for MS-DOS 9.0

This article was previously published under Q46462


The mouse driver protects itself from reentrancy from other mouse function calls but not from interrupt service routines (ISRs) with higher priority.

It is recommended that you do not write an ISR with a higher priority than the mouse hardware interrupt (for example, for the timer interrupt) that calls mouse functions. The result may be undesirable and erroneous. If your ISR is performing a mouse function call, your interrupt may occur during the execution of the mouse function call and start running your ISR again, that is, the original mouse function call may never be finished.

The appropriate routine is to use the mouse function 12/20 to set the mouse user-defined subroutine.

Modification Type: Major Last Reviewed: 9/23/2003
Keywords: KB46462