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DS990 Software
DS990 software is both versatile and efficient.
It
comprehends user requirements in a way not found
in most computers of this class.
DXIO
Operating System
Operators interface with the DXIO operating system
through Model 911 Video Display Terminals (VDTs)
that provide hierarchical menus with supporting fill-
in-the-blank, prompting, and predefined functions.
More than 170 Texas Instruments-supplied system
commands provide powerful and comprehensive
system control. Users can also provide custom
commands that reflect their application terminology.
A broad range of utilities and supporting routines
are built into the system-command structure.
Program memory is dynamically allocated.
Resource management is enhanced by variable-
location roll in/roll out and task-level priority
assignment.
The DXIO operating system has flexible file
management. Types of files supported include
sequentiai, reiative-record, and muitikey-indexed files.
The key-indexed method supports a unique real-time,
self-maintenance capability.
Program and Memory Management.
The
DXIO operating system is a mUltiprogramming
system. User programs that operate under control of
the OX 1 0 system include a composite of tasks,
procedures, and overlays. Programs are installed and
stored in program files. When a program is
activated, its images are loaded into any available
memory area.
An active program can
be
rolled in and out of
several different locations in memory by the DXIO
operating system several times during its execution
to efficiently share memory and processor resources.
When in memory and active, a program competes
with other programs for execution time on a user-
defined priority basis. When a program terminates,
the operating system releases all program-owned
resources including files, devices, and memory. This
unique DXIO program structure is made possible by
a memory-mapping technique. These advanced
memory- and program-management techniques
provide high processor utilization, resulting in high
levels of throughput.
System Command Interpreter.
Operators
interface with the DXIO operating system through
VDTs via the system command interpreter (SCI).
The SCI is a collection of more than 170 procedures
that provide system functions ranging from setting
2
the time of day or initiating compiles to backing up
disks. Commands are at the operator's fingertips via
the SCI. This can save 10 to 30 percent of
development effort on major programs. The
completeness and flexibility of the functions
performed by the SCI make it without parallel in
the minicomputer market. Many of the functions
performed by the SCI are found only on main-frame
machines.
Activation of SCI commands is via a hierarchy of
command menus made available to all types of
system terminals. The command menus provide each
terminal on-line command prompts by logical
grouping.
Custom commands can
be
integrated into the
framework of the DXIO operating system. Users can
combine SCI primitives with their own application
language to provide a user interface that is unique
to the terminology and customary procedures of the
application.
Interactive Operation. The DXIO operating system
features an excellent interactive user interface for
control of the system through SCI. All entries keyed
by
an operator are ffieaningfuHy prompted. Fieids
are easily edited by the operator and are verified by
the system. The number of prompts, and therefore
time, can
be
conserved since all arguments for a
command can
be
entered before the system requests
them by prompt. When a partial list of arguments is
entered, any arguments not already supplied by the
operator or default specified are then prompted.
Batch Operation. The background program at the
terminal may be a copy of the SCI. In this case, the
SCI is interpreting commands in the background
(batch processing). Batch input is from any
sequentially oriented file device but not from the
terminal itself. An operator can initiate batch
processing, query its status, and receive information
concerning its normal or abnormal completion.
Certain interactive commands are inappropriate for
batch operation, but all other SCI commands are
available.
File Management
The DXIO operating system provides a file-
management package that includes a complete range
of file structures and features. The DXIO system can
accommodate many uniquely named data files on a
disk cartridge and provides the necessary
management for allocation of disk space to the files.
The user can specify the amount of space to be
allocated to a file or, more frequently, can specify
that space is to be automatically allocated to the file
as it is needed.
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