INT 15h,  91h (139)      Interrupt Complete                              many

Signals the system that a device is ready to be serviced.

On entry:      AH         91h
AL         Device type (See service 90h)

Returns:       Carry      Set if error, else cleared

                                                                          

Notes:         This service is not available for the PC, PCjr, and
XT dated 11/08/82.

When a device is needed by a process, but access to
it is delayed, the system can perform another task
to achieve maximum performance until the device is
freed up for the process to use. In a multi-tasking
environment, that is the purpose for this service.
The operating system can keep track of which process
is waiting for which device, and perform another
task while the device is busy. After a device is
ready to be serviced, then this function is called
to notify the system that a device is ready.

For example, INT 09h will call this service after a
key has been entered, to signal the operating system
that a key has been entered. Thus if the system was
performing another task while a previous process was
waiting for a keyboard character, then the previous
process could regain control of the system and get
the keyboard character just entered.

See also: INT 15h, 90h
See also: INT 09h

INT 15h, 91h (139) Interrupt Complete many