Texas Instruments 990 User Manual page 98

Applications Programming
4.2.2.3 Request Activation from a Time Delay - Opcode 5.
When an applications program anticipates a response from a
destination program that validates the receipt of previously sent
data, the applications program should execute an SVC with opcode
>4D, I/O opcode 5. After requesting this of activation services,
the program executes a call to the operating system for a time
delay. When reactivated, the program must execute a read call to
retrieve any input data addressed to it. If no data is
re tr ieved, the p'rogram knows the time delay has expired and takes
appropriate action. When input data addressed to the program is
received, activation services activates the program before the
time delay expires.
4.2.2.4 Request Activation from Termination - Opcode 6.
When input data addressed to an applications program is
anticipated on an unscheduled basis, the applications program
should execute an SVC with opcode >4D, I/O opcode 6. After
requesting this of activation services, the program executes a
call to the operating system for termination (in that it requests
to be bid). When any input data is addressed to the program,
activation services bids the program. After being activated,
control returns to the program and it must execute a read call to
retrieve the input data addressed to it.
4.2.2.5 Request Removal from Activation Services - Opcode 7.
When an applications program has been reactivated from a time
delay as a result of time expiration (in that no input data has
been addressed to it), the program should execute an SVC with
opcode >4D, I/O opcode 7. This call removes the program from the
activation services list.
Activation services replaces the latest request made to it with
one that may have been made previously. For example, if an
applications program requested activation from a time delay and
the time delay expired, as is indicated when no data is available
when the read call is made, the program assumes that the
activation services request is still active. If an alternate
action includes termination, the program can make a second
request (to be activated from termination) without requesting
removal from the activation services list.
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