Texas Instruments 990 User Manual page 94
Dx10 hdlc communications package
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- Operation manual (276 pages) ,
- Manual (211 pages) ,
- Installation and operation manual (122 pages)
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Applications Programming
No
provisions
are
made
for
automatic
response from the DID.
Applications
programs
may
establish
their
own
method
for
validating
received and/or transmitted data.
For example, a DID
may send a message back to the SIn
to
validate
received
data.
The DID word always identifies a remote program or device.
The
output
communications
buffers
are
queued chronologically
within the communications system and for the addressed
secondary
sta tion.
4.2.1.3
Read Input Data - Opcode 3.
An
SVC
>40,
I/O
opcode
3, transfers one block of da ta from a
communications input buffer to the applications
program~s
input
data
buffer.
The
applications
program may request activation
services to activate it when input data is addressed to it,
then
request
the
operating
system
to
suspend it (either by a time
delay, suspension, or termina tion until
further
notice).
When
reactivated,
the program may retrieve the input data with a read
call.
One
read
call
retrieves
one
block
of
input
data;
retrieving multiple blocks of input data requires multiple calls.
The DID word always identifies the sender of the data.
The
input
data
blocks
are
chronologically ordered queue
receives
the
oldest
input
call is made.
returned
to
the
caller
from
a
of
input
messages.
The
caller
message on tha.t queue when the read
4.2.2
Activation Services Calls
Activation services are for use
by
applications
programs
that
expect
to
receive
input
data
from
other
programs or remote
devices.
The applications program that expects
to
receive
the
data utilizes activation services in the following sequence:
1. The applications program requests the desired
type
of
service from activation services.
2. The
applications
program
executes
a
call
to
the
opera ting
system to te rmina te, to suspend, or to beg in
a time delay.
3. After the operating
system
deactivates
the
program,
activation
services
begins
a
search
of
the
input
buffers for data addressed to the program.
4. When input data addressed to the
applications
program
is
located,
activation
services
reactivates
the
program.
4-8
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