Texas Instruments DS990 Configuration guide

Commercial Computer Systems
General Information
'IEXt\S INSIRUMENTS.

DS990
Commercial
Computer Systems
General Information
Published by
~ TEXAS INSTRUMENTS
~ INCORPORATED

Copyright@ 19-7-8-by Texas Instruments incorporated. AItRrghts
Reserved. Printed in the United States of America.
No part of this publication may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, electronic,
mechanical, photocopying, recording, or otherwise, without the prior
written permission of Texas Instruments Incorporated.
Texas Instruments reserves the right to make changes at any time to
improve design and supply the best product possible.
The information in this document is subject to change without notice
and should not be construed as a commitment by Texas Instruments
Incorporated. Texas Instruments assumes no responsibility for any
errors that may appear in this document.
1st Edition, July 1978
Texas Instruments Incorporated
Digital Systems Division
P.O. Box
2909
Austin, Texas 78767

Table of Contents
OS990 Commerciai Systems Overview
Page
DS990 Software ............................ 2
DX10 Operating System
..................... 2
File Management
.......................... 2
Error Control and System Log
................. 3
High-Level
Languages and Utilities .............. 3
Program-Development Tools
.................. 3
Communications Software
.................. .4
DS990 Hardware ............................ 4
990 Processor. . . . . . . . . . . . . . . . . . . . . . . . . . . .4
TILINE Peripherals ....................... .4
CRU Peripherals ......................... .4
Communications Equipment and Special
Interface
Devices .......................... 5
990 Chassis Considerations ................... 5
Customer-Support Services
..................... 5
08990 Software
Page
DX10 Operati ng System. . . . . . . . . . . . . . . . . . . . . . .7
System Generation ........................ 8
Program Management
....................... 8
Memory Management
...................... 10
System Command Interpreter
................ 10
File Management ........................... 13
File Types
............................. 13
File Features
........................... 13
Physical Disk Characteristics
............•.... 15
Logical
Input/Output ...................... 15
Error Control
and System Log .................. 16
High-Level
Languages and Utilities ............... 17
COBOL ............................... 17
RPG II ............... " ...... " " .... 20
DBMS 990
............................. 21
BASIC ............. " ................. 22
FORTRAN
............................ 27
Pascal ................................ 29
Sort/Merge. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
Program-Development Tools ................... 31
Interactive Text Editor. .................... 31
Macro Assembler ......................... 31
Link Editor ............................ 32
Debug
Package .......................... 32
Communications Software
.................... 32
Features of 3780 Emulator .................. 33
Comparison with IBM 3780
.................. 33
Control ............................... 34
System Requirements ...................... 34
Components
of 3780 Emulator ............... 34
Customer Information
..................... 35
DS990 Hardware
Page
990 Processor ............................. 37
990 Architecture ......................... 39
Interrupt Structure ...................... .40
990 Address Space ........................ 40
Instruction Set and Addressing Modes
........... 41
990 CPU On-Board Loader .................. 42
Programmer
Panel ........................ 42
990 Memories ........................... 42
990 TILINE ............................ 43
Communications Register
Unit ................ 43
TI LINE Peripherals ......................... 43
Model
DS31 Disk System ................... 44
Model OSlO Disk System
.................. .45
Model DS25 and Model DS50 Disk System ....•... 46
Model 979A Magnetic-Tape Transport
....•...... 47
CRU Peripherals ........................... 47
Model
911 Video Display Terminal ............. 47
Model 810 Printer
........................ 50
Model 2230 and Model 2260 Line Printers ........ 50
Model 733 ASR Data Terminal ............... 51
Model 743 KSR Data Terminal ....•.......... 52
Model 804 Card Reader
.................... 52
Model FD800 Floppy-Disk System
............. 52
Communications Equipment
................... 53
Special Interface Devices ...................... 54
EIA Data Modules ........................ 54
TTL Data Modules ........................ 54
TTY /EIA Terminal Interface Module .......•... 54
32-Bit Input!Transition Detection Module
........ 54
32-Bit Output-Data Module
.................. 54
Digital-I/O-Termination-Panel Module
........... 55
D/A Converter Modules .................... 55
A/D Converter Modules .................... 55
990 Chassis Considerations .................... 55
Standard
Chassis Configuration in DS990 Systems ... 56
Dc-Power Considerations
................... 56
CRU and TILINE I/O Expansion .............. 57
Customer-Support Services
Page
Hardware Installation ........................ 59
Software Installation
........................ 59
Hardware Maintenance
.•..................... 59
Maintenance Agreement
...................... 59
On-Call Service . . . . . . . . . . . . . . . . . . . . . . . . . .60
Fixed-Price Repair Service ................... 61
Software Update ........................... 61
Education Classes .......................... 62
Customer-Support Line
(Hot Line) ..............• 62

Appendixes
A!'pendix Page
A SC I Commands ........................ 63
B 990 Instruction Set ..................... 63
C Memory Requirements ................... 63
o Recommended Memory and Disk Configurations .. 70
E Disk Requirements ..................... 71
F Chassis Planning ....................... 71
Chassis-Power Planning ................. 72
Chassis-Layout Planning ................ 73
G Cabinet Planning ....................... 75
Enclosures ......................... 75
Cabinet-Layout Worksheet .............. 79
H DS990 System Kit Contents ............... 81
I Equipment Specifications ................. 81
J Packing and Shipping .................... 81
K Documentation. . . . . . . . . . . . . . . . . . . . . . . .83
Hardware Manuals
.................... 83
Software Manuals .................... 84
List of Illustrations
Figure
Page
DS990 Model 4 System and Model 6 or Model 8
System
.............................. 1
2 Memory Conservation through Disk
Management
.......................... 10
3 Example of the Menus for Initialization
of a Disk Volume ...................... 11
4 Custom Procedure Example. . . . . . . . . . . . . . . . 12
5 Disk-Volume Layout .................... 14
6 Files and Directory Structure
.............•. 15
7 Multiuser BASIC Components
.............. 23
8 Pascal Programming Cycle ............•.... 30
9 Pascal Block Structure ................... 31
10 Typical Application of 3780 Emulator in
Distributed-Processing Environment
.......... 32
t 1 DS990 Standard and Optional Hardware . . . . . . •38
12 Workspace Pointer and Registers ............ 39
13 990 CPU rr I LIN E Address Space with
Map Option ................•......... 40
14 Model DS31 Disk System ................ .44
-15 -1)531 CbhfrolJerwfth-Follrtflsidlrives": .:~-. . . . .4-5
16 Model OSlO Disk System ...........•.... .45
17 Model DS25/DS50 Disk System ............. 46
18 Model 979A Magnetic-Tape Transport ......... 47
19 Model 911 Video Display Terminal. .......... 48
20 Basic VDT Kit ....................•... 48
21 Model 911 Keyboard ..................•. 49
22 Model 810 Printer ...................... 50
23 Model 2230 and Model 2260 Line Printers ...... 51
24 Model 733 ASR Data Terminal ............. 52
25 Model 743 KSR Data Terminal ............. 52
26 Model 804 Card Reader . ... . . . . . . . . . . . . . . .52
27 Model FD800 Floppy-Disk System
........... 53
28 990 Communications Modules .............. 53
29 Model 990/10 Minicomputer
............... 55
30 Model 990/10 Minicomputer Thirteen-Slot
Chassis ............................. 56
31 Standard 990 Chassis Configuration Chart ...... 56
32 Standard
Chassis Layout .................. 77
33 DS990 Enclosures ...................... 78
34 Dimensional Outline
of Model DS10 Disk on
"Quietized" Pedestal .................... 79
35 Dimensional Outline of DS25 or DS50 Disk on
Pedestal ............................. 79
36 Cabinet-Layout Worksheet ................ 80
37 Minimum Equipment Spacing for
DS990 Systems ........................ 84
38 DS990 Desk-System Packing Crate
........... 85
39 Exploded View of Single-Bay-Desk
Packing Crate
......................... 86
40 Exploded View of Double-Bay-Desk
Packing Crate
......................... 87
41 Typical Rack-Mounted-Disk-Drive Shipping
Configuration
......................... 88
42 Typical Pedestal-Mounted-Disk-Drive Shipping
Configuration
......................... 89
List of Tables
Th~ ~e
1 Areas Served by DX10 SCI Commands ........ 12
2 Device
and File Operations Available through 1/0
Supervisor Calls. . . . . . . . . . . . . . . . . . . . . . . . 16
3 Relative Power of COBOL. ................ 17
4 RPG II Enhancements ................... 21
5 BASIC and Business BASIC Statements ........ 24
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
BASIC Matrix Statements ................. 24
BASIC and Business BASIC Intrinsic
Functions
........................... 25
Conditional Relations for BASIC ............ 25
Operating Commands for BASIC
............ 26
Types
.............................. 28
Hardware Configuration for DX10
3780 Emulator
........................ 34
Hardware Configuration
for TX990
3780 Emulator
........................ 35
Maintenance-Agreement
Service ............. 60
On-Call Service
......................•. 60
SCI Command Index ......•.....•....... 65
990 Instruction Set ..................... 67
DX10 Memory-Estimating Form
............ 68
Recommended Software-Development
Configurations
........................ 70
Recommended Application-System
Configurations
........................ 71
Disk-Pack Sizes ........................ 71
DX10 So~~~e~i~Els.~.~. ~."~ .. ' .. ' ..... , .......•• L ••• 11
Software-Development Disk Requirements ...... 72
Chassis Planning Form ................... 73
Blank 990-Chassis Layout Form ............. 75
Blank CRUrrlLlNE Expansion-ChassiS
Layout Form ......................... 76
Basic DS990 System Kit Configurations ........ 82
DS990 Model 4 System Consolidated
Parts List. . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
DS990 Model 6 and Model 8 Systems
Consolidated Parts List ................... 90
DS990 Model 4 Commercial Consolidated
Parts List .•.......................... 90
DS990 Model 6
and Model 8 Commercial
System Consolidated
Parts List ............. 90
DS990
Basic Software-Package Contents for
HardwarelSoftware Versions ............•.. 91
DS990 Basic Software-Package Contents for
Hardware-Only Versions .................. 92
Optional DS990 Software, Object Format
...... 92
DS990 Hardware Options
...............•. 93
Standard DS990 Equipment Specifications
..... 94
Hardware Manuals .....................• 99
Software
Manuals ..................... 100

DS990 Commercial Systems Overview
The Model 4, Model 6, and Model 8 Systems,
shown in figure
1, combine the performance of the
Model 990/10 Minicomputer with the power
of the
DXI0 disk-based commercial operating system. The
systems are specifically designed for commercial,
interactive, multiuser, multitasking, multilanguage,
and communications applications.
The models differ in disk-file capacity to provide
an orderly growth path. The Model 4 System is a
10M-byte disk-based system suitable for a small
software-development system or medium-scale
application system. The Model 6 System
is a dual
25M-byte disk-based system suitable for medium-
scale software-development and application systems.
The Model 8 System
is a dual SOM-byte disk-based
system intended for medium- to large-scale software-
development and application systems. Physical
packaging differences between the three models are
based on the space requirements of the disk-storage
units.
The base systems are offered in the minimum
configurations that support the full functions
of the
operating system. This allows maximum flexibility in
adding optional software and hardware features to
customize a system. The various models are available
in either equipment-only versions or in versions that
include system software and installation. Software-
included versions provide a licensed copy of the
DX
10 operating system and software-development
facilities, documentation, and a one-year software
SUbscription service for the DXI0 system. A factory-
provided sysgen
is also installed on systems that
include software. Systems are configured and tested
before they are shipped from the factory.
1
Figure 1. OS990 Model 4 System (foreground) and Model 6
or Model 8 System (background)

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 OX10 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.

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
OX10 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.

system, Texas Instruments provides four major
program-development tools: interactive text editor,
macro assembler, link editor, and debug package.
Each
of these operates under SCI and is easily
invoked by
operator commands.
Communications Software
The OXI0 3780 Emulator provides the OS99O family
of commercial systems with a means of remote-job-
entry
(RJE) communications with an IBM 360/370
host computer or another 3780 emulator-equipped
990 computer.
Operation of the IBM 3780 Oata
Communications Terminal is emulated. OS990
systems so equipped can operate in unattended mode
as central
or satellite stations in a distributed
network. Optional auto-call capability is also
provided.
Oata files are transmitted over leased
point-to-point
or switched telephone lines at speeds
up to 9600 baud. Any file or system device can be
specified
to transmit or receive data. Hardware
support of 3780 emulation is provided with the 990
communications interface module to a customer-
supplied modem
or Texas-Instruments-supplied
modem kit
and optional auto-call unit.
DS990 Hardware
The DS990 disk-based systems require a fast, flexible
computer architecture to meet the processing
demands of multiple interactive operations. The
Model 4, Model 6, and Model 8 Systems are based
on a minimum 128K-byte 990 processor with 16K
random-access-memory
(RAM) technology. The
processor features the TILINE· asynchronous, high-
speed
data bus and a memory-mapping technique
that allows addressing of up to 2048K bytes of main
memory.
AU-models employ moving...Jtead- disk drives with
at least one removable disk pack and one additional
fixed
or removable disk pack. This allows copy,
backup,
and transportability of media that are so
important in interactive systems.
Each system includes one 1920-character video
display terminal
and keyboard. A dual-terminal
controller
is included and allows the easy addition of
a second VDT. Additional VDTs are available as
options.
990 Processor
The 128K-byte 990 processor features an advanced
memory-to-memory architecture
and TILINE
asynchronous, high-speed data bus. Current models
offer main-memory capacities up
to 384K bytes of
metal-oxide-semiconductor (MOS), 16K dynamic-
*TILINE is a registered trademark of Texas Instruments.
4
RAM, error-checking-and-correcting (ECC) memory.
The additional
ECC memory is available in various
module sizes.
TILINE expansion to a second chassis
is recommended for these memory modules. Memory
can be further expanded by adding standard 990
options.
The 990 processor includes a dual input/ output
system, a high-speed, asynchronous parallel TILINE
bus, and a low- to medium-speed command-driven
communications register unit
(CR U).
TILINE Peripherals
TILINE peripherals are high-speed I/O systems
which transfer
data to and from 990 memory at
rates that approach the instruction execution rate of
the 990 computer.
The DS990 base system includes one
of the
following disk systems, depending
on the model
selected. The DS31 Disk System has a 2315-type disk
cartridge with 2.8M bytes
of formatted capacity.
This disk drive
is an option on the Model 6 and
Model 8 Systems.
The OSlO Oisk System has a single-spindle, fixed-
and femovabie-piaUer disk drive employing the 5440-
type disk cartridge. Each platter has a 4.7M-byte
capacity
for a combined disk-drive capacity of 9.4M
bytes. This
is the disk drive supplied with the Model
4 System
and is offered as an option on the Model
6
and Model 8 Systems. One DS I0 disk controller
can accommodate up to two DS I0 disk drives.
The DS25 Disk System has a multiplatter disk
pack with 22.3M bytes
of formatted capacity. Dual
DS25 disk drives are employed on the Model 6
System. One OS25 disk controller can accommodate
up to four DS25 disk drives.
The
.DS50 .. Disk.System .. has.amllltiplatter· disk
pack with 44.6M bytes of formatted capacity. Dual
OS50 disk drives are employed on the Model 8
System. One OS50 disk controller can accommodate
up to four DS50 disk drives.
The Model 979A Magnetic-Tape Transport is an
optional TILINE peripheral. Two versions are
available:
an 8OO-bits-per-inch, nonreturn-to-zero
format
and a 1600-bits-per-inch, phase-encoded
format. Both versions use industry-compatible, nine-
track
tape formats. The transport operates at 953
millimetres
per second (37.5 inches per second).
CRU Peripherals
The command-driven communications-register-unit
(CRU) peripherals are low- to medium-speed I/O
systems that transfer data to and/ or from the 990
processor. These peripherals are optional features
that further enhance the DS990 system.

The Model 810 Printer is an impact printer with
9 x 7 dot-matrix character structure and a ninety-
six-character, full ASCII, compressed print set. The
810 printer prints 132-column lines at 150 characters
per second with eight-channel vertical-format control.
The Model
2230 and Model 2260 Line Printers
print 136-column
lines at 300 lines per minute and
600 lines per minute, respectively, with vertical-
format control, internal self-test, static eliminator,
and standard ASCII, sixty-four-character set.
Additional Model
911 Video Display Terminals
are available
as single- or duai-terminal displays with
keyboards and interfaces. A maximum of
twelve
VDTs can be installed in their predefined slots in a
two-chassis configuration. Additional VDTs can
be
installed in other vacant slots by redefining the
interrupt assignments. VDTs can also
be installed in
add-on chassis.
The Model
804 Card Reader is a 400-card-per-
minute reader that takes standard-sized, eighty-
column punched or marked cards.
The Silent 700· Model
733 ASR and Model 743
KSR Data Terminals use Texas Instruments unique
solid-state, thermal printheads for virtually silent
printing of eighty-column lines at thirty characters
per second. A typewriter-style, limited ASCII
keyboard allows operator entries.
The Model FD800 Floppy-Disk System provides
transportable diskette media to smaller members of
the
990 family of systems.
·Silent 700 is a registered trademark of Texas Instruments.
s
Communications Equipment
and Special Interface Devices
Optional communications equipment includes an RS-
232-C communications interface module for
asynchronous and synchronous transmission at
selectable baud rates from
75 to 9600. Other
supporting options include asynchronous and
synchronous modems and auto-call. A variety of
interface modules for custom-device interface or
process monitoring and control are available
including analog-to-digital converters and digital
input and output interfaces. A variety of
Teletypewriter/Electronics Industries Association
(TrY /EIA) interfaces are also available.
990 Chassis Considerations
The 990 computer is packaged in a thirteen-slot
chassis with a programmer panel. The chassis
includes a
4O-ampere power supply and a disk-loader
read-only memory (ROM). One or more chassis can
be added to the system to provide additional
mounting space or dc power.
Customer-Support Services
Texas Instruments customer services encompass the
following areas: hardware installation, software
installation, hardware maintenance, software update,
education classes, and telephone hot
line. Individual
services can
be selected to best suit application and
customer requirements.

6

DS990
Software

DS990 Software
DS990 software features a versatile and powerful
operating system, the DX
10 operating system. File-
management and error-control features make this
operating system an extremely efficient one. A wide
variety of high-level languages are available with the
DS990 system. Among these are COBOL,
DXIO Operating System
The operating-system software selected for a
computer installation has a major effect on the
throughput, reliability, and usability of the system.
The disks, processors, memories, terminals, and other
physical resources of a computer system represent a
potential for performance. The operating system
controls the total system resources and allocates
them to the various tasks required in the user's
application programs. An operating system also
provides other necessary system services and utilities,
such as interrupt handling and input/output (I/O)
device service routines. The operating system relieves
the individual application program of these overhead
responsibilities, which greatly reduces the opportunity
for error and simplifies application programming.
The
DXIO operating system is Texas Instruments
powerful disk-based operating system; it is one of
the most sophisticated, flexible, and versatile
computer operating systems available. First released
in
1976, the DXIO system is a proven product that
has been refined
by operation within Texas
Instruments and
at customer sites around the world.
The
DXIO system is a general-purpose,
multitasking operating system, which
is optimized for
multiterminal interactive operations. The operating
system makes each terminal appear to have exclusive
control of the system; so the existence of other
terminals
is transparent to any individual user.
Batch-processing tasks can
be initiated from any
terminal without interfering with interactive terminal
operations.
The
DXIO operating system has extensive file-
management capabilities. The
DXIO system creates
files, allocates disk and memory space for
files,
transfers files between disk and memory as required,
and controls read access, write access, deletion, and
file sharing by mUltiple users. The operating system
supports sequential files, relative-record
files, and
multikey-indexed
files with up to fourteen keys.
7
FORTRAN, RPG II, BASIC, Pascal, and DBMS
990. Software-development tools include an
interactive text editor, macro assembler, link editor,
and debug package. These features enable DS990
software to comprehend user requirements in a way
not found in most computers of this class.
The
DXIO operating system incorporates a number
of program-development utilities, which greatly
reduces development time and improves effectiveness.
Programs can be developed under the DXIO
operating system to execute on the DS990 system or
on the smaller floppy-disk-based or memory-resident
systems in the
990 family. Program-development
packages are sold as extra-cost options to many
operating systems; however, they are included as part
of the DX
10 system because program development is
a major application of the DS990 systems. The
program-development utilities include an interactive
text editor, relocatable macro assembler, link editor,
and interactive debugger.
Many users prefer to write programs in one or
more
of the major high-level programming
languages. Compilers/interpreters for FORTRAN
(with Instrument Society of America (ISA) process-
control extensions), COBOL, BASIC, Business
BASIC, RPG II, DBMS 990, and Pascal are
available as optional features of the DXI0 operating
system.
The
DXIO operating system includes the device
service routines necessary to communicate with the
standard and optional DS990 110 devices, such as
the Model
911 Video Display Terminals (VDTs),
disk systems, Model
810 Printers, Model 2230 and
Model
2260 Line Printers, Model 979 A Magnetic-
Tape Transport, and Silent
700 terminals. Special
device service routines can
be linked to the DXIO
system. The DXIO system uses logical 1/0, which
further isolates an individual user program from the
characteristics of the
I/O device. Logical I/O allows
an
I/O device to be treated as a file that is
referenced by a logical unit number (LUNO).
This simplification allows the user to concentrate
on the application problem rather than on device
details. Logical
I/O is particularly useful for
program development in which a
file or another I/O

device can be substituted for the device that will
ultimately be used.
A versatile, interactive, fully prompted system
command interpreter (SCI) allows direct
communication between the operating system
and the
user. This powerful command interpreter
is a major
convenience
of the DXIO system.
The DXIO operating system
is a modular
operating system
that can be customized for each
customer's site. Customizing the operating system
improves the efficiency
of resource utilization. An
interactive system-generation (sysgen) program
is
supplied with the DXIO system to provide a fast and
convenient means of implementing the custom
system.
To protect Texas Instruments investment and its
customers' interests, the DXIO operating system
is
only available on a licensed basis. The license
includes software updates for one year following
purchase with
annual renewal subscriptions available.
(The software sUbscription service
is also available to
users who allow their subscriptions to lapse and then
decide
to update their systems.) The DXIO software
license also includes installation support (basic
system generation
and verification) by a Texas
Instruments customer engineer.
For additional
information, refer
to the 990 Computer Family Price
List.
System Generation
The DX 10 operating system is a modular operating
system
that can be customized for each customer~s
site. Customizing the operating system has the
following advantages:
• Reduces disk- and memory-space requirements
(Eliminates unnecessary modules; such· asdeviee
service routines for equipment not included in the
customer's system)
• Increases operating speed (Eliminates code
sequences associated with unnecessary modules)
• Eliminates replication of device service routines
for multiple installations
of a device type
• Adds device service routines for nonstandard
devices
• Adds user-defined operating-system service calls
• Adds user-defined extended operation (XOP)
processors
• Adjusts operating-system parameters for best
efficiency in a given installation.
The DXIO operating system
is supplied to a
DS990 purchaser on a media that is compatible with
the system. Unless otherwise specified, the DXIO
system is supplied on a DSIO (5440-type) cartridge
8
for DS990 Model 4 Systems, on a DS25 disk pack
for DS990 Model 6 Systems, and on a DS50 disk
pack for DS990 Model 8 Systems.
The DXIO disk includes a standard DXlO
operating system
that is compatible with the basic
DS990 configuration (including standard options).
The disk also includes a complete set
of individual
DXIO component modules, which can be used in the
development
of the custom DXIO system. An
interactive sysgen program builds the custom system
to user specifications. The sysgen program uses
prompting
and tutorial displays to lead the user
through system generation. When system generation
is complete, a complete set
of specifications is
displayed for user approval. At this point, the user
may back out, revise specifications, store
the custom
system as
an alternate system, back it up with an
additional copy, or activate it as the primary
operating system.
Program ~anagement
A multitasking operating system allocates the
resources
of a single computer system to a number
of individual user programs in such a way that each
user appears
to have exclusive control of the
computer system. Multitasking maximizes the
amount of useful work obtained from a given
amount of computer hardware.
User programs that operate under control of the
DX 10 operating system include a composite of tasks,
procedures,
and overlays. Programs are installed and
stored in disk program files in memory-image form.
When a program
is activated, its memory images are
rolled in from the disk and loaded into
any available
memory areas. This specific activation
of a program
is
call~da task. M ultipletaskscanbe in memory at
any time. A scheduler in the DXIO operating system
allocates central-processing-unit (CPU) execution
time
to the various tasks. Conceptually, every task is
in some partial state of completion with one task
actually executing while the others are either active
(in queue, ready
to execute) or suspended (not ready
to execute).
The process
of removing one task from execution
and putting another into execution is called
scheduling. Tasks scheduled by expiration
of a time
limit are called time-shared tasks. Time-shared tasks
are queued
at different priority levels. A
sophisticated scheduling algorithm allocates time
slices
at the various priority levels; so no task is
locked out.
The architecture
of the 990 computer family
supports multitasking software. The workspace
architecture allows rapid context switches with a

minimum of overhead time. The general registers are
not saved or restored each time a different task is
scheduled. Memory mapping allows each task to
execute in an independent, fully protected address
space.
It permits the logical address space of tasks
to be segmented into up to three physical memory
areas. Mapping also protects the operating system
from destruction by errant application programs.
Priority Scheduling. The DXIO operating system
requires
that each task have a defined priority level.
Four priority levels are available: level 0 (highest)
through level 3 (lowest)
and level 4 (floating). Level
ois reserved for DXIO internal use. Higher priority
tasks are granted execution preference over lower
priority tasks. However, even lower priority tasks are
guaranteed some execution time. Tasks designated
with equal priority execute in round-robin fashion.
Each priority level
is allocated a number of
execution units of time. When all the allocated units
have been used, one unit
of time is given to the
next lower priority task.
Tasks with Variable Priorities. When a task is
installed, it may be designated with a floating
priority level (level
4). In this event, the task is
loaded at priority level I when execution is first
desired. After initial execution, its priority
is
dynamically set to level I for terminals and level 2
for other devices
on each 110 request. Task priority
is lowered
to the next lower level (never below level
2) after a specified number of time slices when it is
executing. A floating priority (managed by the DXIO
operating system) permits rapid response to 1/0
events and deemphasizes the task during periods
when task processing could compute bind the
system.
For example, application programs that
function interactively normally are installed with a
floating priority level.
Shared Procedures and Replicated Tasks.
Having several concurrent executions of the same
program is desirable in many multiterminal
environments
or in industrial applications where
symmetrically alike devices are controlled.
An
example might be a program serving bank tellers
that interacts concurrently with several tellers.
In many cases, the procedural
part of the program
is
common to each of the concurrent executions;
however, the
data is unique to each separate
execution. Under the
DXIO operating system, the
shared procedural part
is called a procedure while
the unique part
is called a task. The three allowed
program segments are therefore allocated
to two
procedures
and one task.
9
A program operating under the DXIO operating
system
can consist of a task and none, one, or two
procedures. The procedures
can be shared with other
executing tasks. Sharing procedures conserves
memory usage because replicating the procedural
part of a program is unnecessary. Conversely, the
task
part is indeed unique to each separate
execution. The
DXIO operating system provides a
convenient mechanism
to replicate tasks for mUltiple
executions. In cases where each concurrent activation
of a program has the same initial data, only one
program image need be stored on disk. For each
terminal, a task
can be replicated from a single
image installed in a program file
on disk.
Replicating tasks conserves disk space
and time
because installing a copy
of the same initial task for
each possible concurrent activation
of a program is
unnecessary.
Sharing Data among Tasks. Under the DXIO
operating system, a block of data can be shared
among two or more tasks through the use of a
shared-procedure segment. A procedure can contain
data that is shared among several tasks.
Overlays. As programs become large, they can be
partitioned
to allow only a portion of the program
to be resident in memory at a given time. The
overlay support provided by the
DXIO operating
system provides the mechanism
to accomplish the
disk-resident part. The remainder
is divided into
disk-resident overlays.
When
an overlay module is required, the program
initiates a supervisor call
that loads it into memory.
Overlay modules can be further segmented into a
lower level consisting
of a "root" and overlays.
Multilevel overlay structures are supported by the
link editor.
Task Activation by a Program. Any task can
request
that another task be activated. Both tasks
then become concurrently active. The
DXIO
operating system supports the identification of a
station with which the new task
is to be associated.
In this manner, all of the station-local logical-I/O-
unit assignments are available
to the next task.
Furthermore, the requesting task
can specify that it
be suspended until termination
of the activated task.
This provides a convenient mechanism for a master
application program serving a station
to activate
subprocesses either in parallel with the master
program
or instead of the master program. In the
latter case, the master program resumes execution
when the subprocess completes.

Program Files. All tasks, procedures, and
overlays are installed in structures referred to
as
program files. These files are based on the
expandable relative-record
file type and contain
program images in blocks corresponding to
file
records. An internal directory is maintained within
the program
file. This internal directory contains
pointers to each image on the
file as well as relevant
information about the images. Typically, the
DXIO
operating system requires two disk accesses to load a
disk-resident task, procedure,
or overlay: one for the
directory entry and one for the image.
Roll in/Roll out
Program 1
Program 2
~orkArea~
One program file is designated as the system
program file. The system program file initially
contains only programs that constitute parts of the
DXIO operating system. Other program files can be
created to hold application programs.
Program Identification. Program parts stored in
program
files can be retrieved by task, procedure, or
overlay numbers specified
at installation time. A
program can
be installed with or without the
replicative attribute.
Overlays
£:.. ~ Root
Root
=3
'- ~OVerlay 1
-
.. ~ Overlav2
~Overlav3
Figure 2. Memory Conservation through Disk Management
~eliDory ~anageliDent
The DXIO operating system uses the 990 mapping
option to dynamically allocate memory to the disk-
resident task segment, procedure segment, and file-
blocking buffers. The allocated blocks can
be
released from memory and rolled to disk as needed.
The roll-in/roll-out mechanism, shown in figure
2,
ensures efficient use of main memory and CPU time.
The DXI0 operating system incorporates an
algorithm that permits programs of high priority to
preempt memory space from those
of lesser or equal
priority. Any program can preempt space from a
suspended program. Whenever insufficient memory
space
is available to permit the operating system to
execute a program, the
DXIO system seeks lower-
priority
or suspended-task segments and dispatches
these programs to disk. This process
is called roll
out. Similarly, when the task and priority mix
indicates, the rolled-out program
is rolled in from
the disk and execution resumes. The memory-
mapping feature permits a program segment to
be
restored to a different physical memory space than it
occupied at the time it was rolled out. The priority-
oriented roll-in/roll-out mechanism guarantees high-
10
priority tasks immediate access to memory to
respond to users or other external stimuli.
File blocks are allocated in the dynamic memory
area. Any blocks of data retained by the
DXIO
operating system from recent disk transfers can be
preempted by the operating system if the memory
space
is needed. These blocks are written to their
appropriate
file location on the disk (if they have
been updated) to acquire memory space.
SysteliD COliDliDand Interpreter
The DXIO system command interpreter (SCI)
provides an interactive, conversational user interface
at a terminal and also provides a background batch-
processing mode. The SCI
is a collection of more
than
170 procedures that provide system functions
ranging from setting 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

Any portion of the sequence can be
skipped by going directly to the command
desired.
Figure 3. Example of the Menus for Initialization of a Disk Volume
11

performed by the SCI are found only on main-frame
machines. Table I lists the general categories of
functions provided by the DXIO operating system
and initiated by the SCI.
Appendix A lists all standard SCI commands
available with the
DXIO operating system. 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. The example in figure 3 illustrates the
menus for initialization of a disk volume.
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. Figure 4
is an example of a custom
procedure.
Table 1. Areas Served by DX10 SCI Commands
Log in and out
Time and date setup and ill4uiry
Disk volume initialization, installation,
and unloading
Disk directory backup, restore, and copy
Directory and file creation and deletion
Synonym support
File alias name
File name changing and protecting
Directory and file viewing and listing
Directory and file copying
Logical unit assignment, positioning, and release
System I/O status display
-
·Systemtaskstatusdisplay
Program activation and control
Batch command input, activation, and status
Station control (user ID, terminal status, etc.)
Program installation and deletion
System log activation
Program debugging including:
Breakpoints
Memory/disk
dump or display
Decimal/hexadecimal
arithmetic aid
Interactively controlled program trace
Text Edit control
COBOL, RPG II, DBMS 990, Business BASIC,
BASIC,
FORTRAN, and Pascal compilers and
assembly-language assemblies
Link Edit activation
Sort/Merge activation
12
SELECT ONE OF THE FOLLOWING
COMMAND GROUPS
/PROG PROGRAM OPERATIONS
/ENTRY -
DATA ENTRY
\ /APPL APPLICATIONS
.l APPLICATIONS
/ACCT
-ACCOUNTING
/PAY
PAYROLL
/INV
-
INVENTORY
/ANAL
-SALES
ANALYSIS
~
PAYROLL
I
/WKPAY -
WEEKLY PAYROLL
/MTD
-
MONTH TO DATE
/YTD
-
YEAR TO DATE
/W2 -
W2 PROCESSING
\ /W4 -W4 PROCESSING
J WJ:J:1l1 v PAVDnl I
7 ------- ....... _-- ';
NAME
EMP.NO. ___
DEPT. RATE
REG. HRS.
O.T.HRS. __
DEDUCTIONS INS.
MED.
CONT' __ j
Figure 4. Custom Procedure Example
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 meaningfully prompted.
·Fieldsare-easily edited by tne'opetaI6tario'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 DXI0 operating system is based on a file-
management package that includes a complete range
of file structures and features. The DXI0 system can
accommodate many uniquely named data files on a
disk pack and can allocate disk space to the files.
The amount of space allocated to a
file can be as
small as two disk sectors or as large as all of the
available space on the disk cartridge. The user can
specify the amount of space to be allocated to a
file
Of; more frequently, can specify that space is to be
automatically allocated
to the file as it is needed.
File Types
Three major file types are supported by the DXI0
operating system: sequential, relative-record, and
multikey-indexed
files.
Sequential Files. Sequential files are useful for
recording data records in the order received.
Similarly, data
is returned in the same order. A
pointer to the current file position
is kept by the
DXI0 operating system for each active assignment to
the file.
As each record is read or written, the
pointer
is advanced. In sequential files, no valid data
can exist beyond the most recently written record.
The only exception to this rule
is that a limited
rewrite
of a record is supported. A sequential file
can be segmented, and support for mUltiple end-of-
files within a sequential file
is provided. Several
programs can concurrently read a sequential disk
file
at different positions in the file. A sequential file
cannot be shared if
it is being modified.
Relative-Record Files. Relative-record files are
optimized for rapid random access. Fixed-length
records are accessed by supplying the DXI0
operating system the record number within the
file.
Such files are useful when the data lends itself to
computation
of a record number. The DXIO system
increments the caller's record number after each read
or write; so a sequential access is permitted. One
end-of-file record is maintained.
Multikey-Indexed Files. 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. (A key
is a string of up to 100 characters at a fixed
position within the record.) One of the fourteen
possible keys must be selected as the primary key.
All other keys are known as secondary keys.
Primary keys must be present in all records, but
secondary keys can be optionally absent in any given
record within the file.
13
For example, an employee' file can be constructed
so the data record for any given employee can be
accessed
by supplying the employee's name, employee
number, social security number, or any other
designated key.
Key values for both primary and secondary keys
are kept in indexes within the files. These indexes
are hierarchically structured. This allows both rapid
random access
to any record within the file or
sequential access to all records in the file in the
stored order
of any selected key.
The user can perform the following types of
functions with key-indexed files:
• Randomly read any record.
• Insert and delete records. (Records are
automatically blank suppressed on insertion, and
duplicate key values are allowed.)
• Establish a generic file position as in a COBOL
start command.
• Read files sequentially in the sort order of a given
key starting at an established
file position. (Files
can be read in ascending
or descending order.)
• Add, delete, or change a secondary-key value
when records are updated.
Multikey indexing provides a unique self-
maintenance capability. Deleted
or added keys are
automatically removed
or inserted in the sorted key
lists. The DXI0 operating 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 may
or may not allow access to any given feature,
depending on the syntax
of the language. Assembly-
language programs can be written and called from
high-level-language programs to allow indirect access
to a feature.
Record Locking. The DXI0 operating system
supports locking individual records within a file.
This feature allows a program exclusive access to the
locked record until that record
is unlocked. An
example might be locking an inventory record while
updating the quantity in stock. The lockout prevents
programs responding to other terminals from
updating the same quantity before the first update
is
complete.