Timeouts - IBM 5170 Technical Reference

OIH
yes (2 sec) IBM Personal
Computer AT diskette
02H no IBM Personal
Computer AT
keyboard
OFDH
yes (1 sec-write) diskette motor start
(625 msec-read)
OFEH yes (?? sec)
printer
The asynchronous support has been omitted. The IBM Personal
Computer AT Serial/Parallel Adapter will generate interrupts,
but BIOS does not support it in the interrupt mode. Therefore,
the support should be included in the multi-tasking system code if
that device is to be supported.
Timeouts
,..-...., In order to support timeouts properly, it is necessary for the
multi-tasking dispatcher to be aware of time. If a device enters a
busy loop, it generally should remain there for a specific amount
of time before indicating an error. The dispatcher should return
to the BIOS wait loop with the carry bit set if a timeout occurred.
SYS REQ'Key
The following describes the use of the SYS REQ key in a
multi-tasking environment.
It
assumes that tasks used are
cooperative in some manner. The system must employ a task
monitor to allow the user to select various tasks. This selection
may be for starting tasks, terminating tasks, supplying input to
tasks from the keyboard, or any other function that requires user
input.
Compatibility 9-15