Int 31H Function 0900H
Get and Disable Virtual Interrupt State
Disables the virtual interrupt flag and returns the previous
state of the virtual interrupt flag.
AX = 0900H
Virtual interrupts disabled
Carry flag = clear (this function always succeeds)
AL = 0 if virtual interrupts were previously disabled
AL = 1 if virtual interrupts were previously enabled
- AH is not changed by this function. Therefore, the previous state
can be restored by simply executing another Int 31H. See Int 31H Function 0901H.
- A client that does not need to know the prior interrupt state can
execute the CLI instruction rather than calling this function. The
instruction may be trapped by the host and should be assumed to be