Texas Instruments 990 User Manual page 254

Glossary
Data buffers
Storage areas allocated within an application program to
hold data required by the program.
Data Link Level - (Level 2)
Level 2 software provides data link control for an
-unbalanced (multipoint) line operating in the HDLC "normal
response" mode. A subset of the International Standard High
Level Data Link Control (HDLC) protocol is specified for use
with the
D~lO
HDLC Communications Package. Included in this
control are message sequence counting and HDLC frame
formatting procedures.
Device service routine
See DSR.
Destination ID
See DID.
DID (destination IO)
The network IO assigned to stations or applications programs
that have data sent to it.
Download directory
A directory maintained by the communications package that
contains the file names of formatted operating systems for
secondary stations and the station IDs to which the
operating systems are assigned.
Download preprocessor
The utility program in the primary station that converts a
standard DXlO object file into a relocated binary formatted
object file and stores the object file in the download
directory.
Download task
This task accesses the files built by the download
preprocessor and transfers records from these files to the
downloading secondary station via the communications
package.
Downloading
A procedure by which the operating system or stand-alone
program for a secondary station is sent from the primary
station over the communications line. TX secondary stations
require an DXIO HDLC Communications ROM loader for
downloading.
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