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File Types.
Three major file types are supported
by the DXI0 operating system: sequential, relative-
record, and multikey-indexed files. Sequential files
allow records with concurrent reads. Relative-record
files provide rapid access to fixed-length records in
either random or sequential mode. In multikey-
indexed files, variable-length records are accessed by
providing the DXI0 operating system anyone of up
to fourteen keys by which the data is known. The
keys are in sorted order and allow rapid access to
data addressed by the keys.
rvtultikey indexing
provides
a unique self-
maintenance capability. Deleted or added keys are
automatically removed or inserted in the sorted key
lists. The DX 10 system automatically expands or
contracts the key lists and eliminates much of the
necessity for periodically rebuilding and reorganizing
files.
File Features.
Various file features and file types
are available to the assembly-language user. High-
level languages mayor may not allow access to any
given feature, depending on the syntax of the
language. Some of the supported features include:
• Record locking
• Temporary files
• Blocked files
• Deferred or immediate write operation
• Delete and write protection
• Access privileges
• Blank compression and adjustment
• Expandable files
• Blank compression.
Error Control and System Log
The DXI0 operating system incorporates several
error-control features and supports an optional
system log. The 990 mapping feature protects the
OX 1 0 system from destruction by errant application
programs. An optional end-action routine analyzes
abnormal termination and takes appropriate recovery
steps.
High-Level Languages and Utilities
COBOL, RPG II, DBMS 990, BASIC, Business
BASIC, FORTRAN, Pascal, and Sort/Merge
packages are available as options on all DS990
systems.
The COBOL compiler conforms to the American
National Standards Institute (ANSI) COBOL subset
(ED lX3.23-1974) and incorporates extensions to this
subset to provide added capabilities.
The RPG II compiler conforms to the IBM
System/3* RPG II specifications with certain
equipment and teleprocessing exceptions. Texas
3
Instruments version of RPG II is video-display-
oriented and provides one-line-at-a-time forms or
multiline listings.
Texas Instruments DBMS 990 is a modular data-
base management system specifically designed for
minicomputer applications. DBMS 990 includes a
data-definition language (DDL) for defining the
logical structure of data and a data-manipulation
language (DML) that interfaces through COBOL for
storing and retrieving data. A number of utilities
and security features can optionally
be
used within
the modular structure of DBMS 990.
The BASIC** language is a version of Dartmouth
BASIC as described in BASIC
Programming,
by
Kemmeny and Kurtz, with certain extensions to
enhance its use. The extensions are integer arithmetic
type, expanded string handling, CALL, and
subprograms.
BASIC is aimed at the scientific user. Business
BASIC, a variation of BASIC, is an easily
understood, business-oriented, application-solving
language. Single-key-indexed file input/ output (I/O)
and limited-output editing capabilities are included to
provide a check-printing capability.
The FORTRAN compiler conforms to the ANSI
standard FORTRAN, or FORTRAN IV. The
compiler also incorporates the extensions
recommended by the Instrument Society of America
(lSA-S61.1, 1975 and ISA-61.2, 1976).
Pascal is a general-purpose language well suited
for a variety of applications. Originally designed as a
language for teaching a systematic concept of
programming, Pascal is straightforward to learn and
to use. Its readability makes the language especially
useful when programs must
be
maintained by users
other than the original author.
The DXI0 operating system supports a
comprehensive Sort/ Merge package that can be
accessed in several ways. SCI provides commands to
access Sort/ Merge in batch or interactive mode.
COBOL, RPG II, FORTRAN, and BASIC
programs can interface with Sort/ Merge by using the
CALL statement. Both sort and merge processes
support record selection, reformatting on input, and
summarizing on output. Ascending key order,
descending key order, or an alternate collating
sequence can be specified.
Program-Development Tools
In addition to a comprehensive set of utilities that
operate in conjunction with the DXI0 operating
*IBM System!3
is
a registered trademark of IBM.
**BASIC is a registered trademark of Dartmouth College.
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