top - download
⟦7b18757e6⟧ Wang Wps File
Length: 12608 (0x3140)
Types: Wang Wps File
Notes: ASC - GREECE, SYS. DESCR.
Names: »4689A «
Derivation
└─⟦65419b34f⟧ Bits:30006022 8" Wang WCS floppy, CR 0440A
└─ ⟦this⟧ »4689A «
WangText
ASC - GREECE,
PART III
SYS/84-03-10
SYSTEM DESCRIPTION
Page
2̲ ̲ ̲F̲U̲N̲C̲T̲I̲O̲N̲A̲L̲ ̲C̲A̲P̲A̲B̲I̲L̲I̲T̲I̲E̲S̲
2.1 S̲Y̲S̲T̲E̲M̲ ̲O̲V̲E̲R̲V̲I̲E̲W̲
The ASC provides a complete facility for fast reliable
and flexible distribution, management and control of
the AFTN traffic.
The ASC will meet all requirements for speed, capacity,
reliability and expandability.
The system can manage a significant number of incoming
and outgoing messages per hour. Availability is ensured
by the flexibility and modularity of the system, which
provides easy and fast maintenance, as well as implementation
of fault-tolerancy and dualization of modules.
F̲e̲a̲t̲u̲r̲e̲s̲
o M̲o̲r̲e̲ ̲r̲e̲l̲i̲a̲b̲l̲e̲ ̲c̲o̲m̲m̲u̲n̲i̲c̲a̲t̲i̲o̲n̲ through computer control,
equipment dualization and system redundancy.
o H̲i̲g̲h̲e̲r̲ ̲s̲u̲r̲v̲i̲v̲a̲b̲i̲l̲i̲t̲y̲ through alternative paths
and automatic rerouting.
o T̲i̲g̲h̲t̲e̲r̲ ̲c̲o̲n̲t̲r̲o̲l̲ through centralized computer coordination,
supervisor visibility, and automatic collection
of statistics and status information.
o O̲p̲e̲r̲a̲t̲i̲o̲n̲a̲l̲ ̲s̲i̲m̲p̲l̲i̲c̲i̲t̲y̲ through automatic distribution,
and minimum operator intervention.
o E̲a̲s̲i̲e̲r̲ ̲e̲x̲p̲a̲n̲s̲i̲o̲n̲ through flexible, common and interchangeable
hardware/software modules.
o M̲e̲s̲s̲a̲g̲e̲ ̲S̲w̲i̲t̲c̲h̲i̲n̲g̲. Store and forward switching
of messages.
o E̲x̲p̲a̲n̲s̲i̲o̲n̲ ̲F̲e̲a̲t̲u̲r̲e̲s̲. Fully dualized system with
n+1 redundancy.
o G̲r̲e̲a̲t̲e̲r̲ ̲e̲f̲f̲i̲c̲i̲e̲n̲c̲y̲. Faster delivery and higher
throughput through real-time multiplexed use of
network facilities.
The ASC consist of the following main elements.
o Flexible modern circuit connections to international,
local and domestic circuits.
o Store and forward CR80 computer system.
o Terminal positions with VDU and printer for system
supervision and message corrections.
The ASC CR80 store and forward message switch can be
implemented both as a single system and as a fully
fault tolerant dualized system. The proposal describes
both systems. The differences in the two solutions
is limited to the internal hardware structure and modules,
which results in the higher availability and fast performance
of the dualized system. The configurations for the
two systems are shown in chapter 3. The availability
features described in the following sections can not
always be fully exploited in the single system.
2.1.1 A̲S̲C̲ ̲F̲u̲n̲c̲t̲i̲o̲n̲s̲
The functional aspects of the ASC comprise three principal
functions:
o The message switch
o The Supervisor/Operator interface
o Statistic and Reporting.
The message switch implements all essential functions
for automatic storing and forwarding of messages. This
includes line handling, processing of input signals,
output processing, routing and queueing, and message
storage and retrieval.
The supervisor/operator interface implements a user
friendly man-manchine interface, enabling human intervention
and control, where necessary. The supervisor function
can due to safe operations only be allowed at one position
at a time; examples of the supervisor capabilities
are routing table changes and allocation of functions
to the other position. The operator function includes
the reject message processing and can be done at the
same position as the supervisor or at both positions,
if required.
Finally, facilities are provided to produce required
statistic reports, and log/printouts used to evaluate
functioning of the ASC and ensure optimum performance.
2.1.2 C̲o̲m̲m̲u̲n̲i̲c̲a̲t̲i̲o̲n̲s̲
The baseline system is designed for the specified initial
capacity of phase 1. But due to the modular design
of the hardware is it possible to expand to virtually
any number of circuits, not only the indicated increase
in international, local, and domestic circuits, but
also with multiple channels on individual circuits.
The line interface hardware is general purpose and
also used in the communications systems for Air Canada
and American Airlines. It can accommodate much higher
transmission speeds; the Line Terminating Unit (LTU),
which handles four circuits is designed for 9600 baud.
The line interface hardware is capable of operating
with full duplex, half duplex and simplex lines.
The modular design of not only hardware but also software
facilitates expansions and extendability. The software
modules used for the ASC are from the same baseline
as the Air Canada and American Airlines communications
software which is employing CCITT X.25 packet switching
up to OSI level 3. The external network environment
accommodates the SITA, ARINC, and CNT networks.
The migration to the future CIDIN* network with the
expected level 3b and level 4 will not pose any problems
and off-the-shelf software will be available from the
present CHRISTIAN ROVSING A/S projects.
* CIDIN: Common ICAO Data Interchange Network
2.2 S̲Y̲S̲T̲E̲M̲ ̲D̲E̲S̲I̲G̲N̲ ̲C̲O̲N̲S̲I̲D̲E̲R̲A̲T̲I̲O̲N̲S̲
The many functional and operational features inherent
in the CR80 computer systems for ASC go beyond the
mere physical size variations and expansion options.
The computer family is designed for high reliability,
high flexibility systems, such as communications processors,
front-end processors, data concentrators and packet-switched
networks.
Flexible variation in the size and structure of the
CR80 systems are permitted by the unusual degree of
hardware and software modularity. The hardware essentially
consists of fast transfer buses joined to each other
by adapters which allow units on one bus to access
those on another. Dualization at the internal level
and multiple redundancy at the system level provide
a CR80 hardware architecture which is exploited by
the XAMOS software operating system and programs to
survive operational failure of individual components.
o Distributed processing throughout the CR80 computer
family
- Multiple Central Processors
- Multiple CPU's in Central Processors
- Individual Microprocessors in each Peripheral
Controller Module
- Fast separate processor for Interrupt Preprocessing
and Data Channel management.
Reliability, which is increasingly becoming of concern
in real-time and distributed network applications,
is achieved in the CR80 computer systems by applying
unique architectural concepts. The CR80 hardware/
-software architecture treats all multiprocessors as
equal elements not absolutely dedicated to a specific
role. Fault tolerance and backup are achieved through
an n+1 redundance scheme without preassignment of system
functions to specific processors. This is in marked
contrast to the more common rigid dualized configurations
often encountered in dedicated applications with on-line
master/slave arrangements, or off-line backup with
switchover facility.
o Fault Tolerancy
- No-break computing supported by numerous unique
hardware, software and maintenance features
to achieve mean time between system failures
in the order of years.
- Multiple Central Processor incorporation of
Peripheral Controller modules providing alternative
processing paths.
- Economic N+1 Central Processor redundancy.
- Economic N+1 Communication Interface redundancy.
- Dual Powering of Peripheral Controller modules
safeguards against single power failures.
- Redundant Fan Units ensure sufficient cooling
of equipment in the event of Fan breakdown
or failure in a mains phase supply.
- Short mean time to repair ensured by major
system components exchangeable from the front
with no cable detachment or special tools needed.
- Extensive Quality assurance and control program
during design and production for achieving
and maintain the CR80 high level of module
reliability.
- Maintenance and Configuration Processor subsystem
supervises Power Supply voltages and environmental
conditions and provides reconfiguration of
the computer in response to errors reported
by on-line diagnostics, self-checks and status
reporting.
Coupled with reliability is maintainability. The CR80
computer system family offers a very advanced concept
of on-line serviceability and extendability. It offers
an integral maintenance and configuration processor
for system supervision and unattended operations.
o On-line serviceability and extendability
- Computers partioned in self sustained physical
subunits complete with power supply and cooling.
- Physical subunits galvanically isolated from
each other and interconnected via high speed
dual or multiple redundant long distance data
highways, omitting ground loops normally limiting
size and on-line extension of computer systems.
- All major modules, inclusive the power supplies
and Fan Units, are insertable and exchangeable
from the front without special tools.
- On-line exchange and addition of modules without
power down provided by electronic power switches
and bus high impedancing circuitry in the individual
modules.
- Extensive individual module self test at power-on
provides immediate visual indication to operator
of hardware status.
- Wide range of maintenance and diagnostic programs.
- Early warning of error prone conditions and
preventive fault correction made possible by
the Maintenance and Configuration microcomputer
monitoring power supply voltages and environmental
conditions of subunits.
o Maintenance and Configuration Processor
- Stand-alone system Watchdog microcomputer monitors
equipment status through physical sensing.
- Voltage variations of power supplies monitored
with A/D converters.
- Fault Tolerancy computer reconfigurations,
based on accumulated on-line diagnostics, selfchecks
and status reporting.
- Distributed monitoring and control of all computer
subunits through separate redundant, galvanically
isolated connections.
- Fail-safe switch-over to manual set-up of configuration
in case of error in the Maintenance and Configuration
Processor itself.
- Manages the economic N+1 redundancy switch-over
of communications lines.
o Extensive use of LSI technology
- High equipment density achieved by use of RAM's,
PROM's, CPU's, USART's, FIFO's, Programmable
Logic Arrays and microprocessors.
- Low power consumption, allowing for forced
air cooling of even the largest computer configurations.
- Very low space requirements of packed computers.
- High speed based on Schottky-TTL technology.
o Powerful CPU utilized
- Microcycle time 250 nanoseconds.
- 16 bit instructions.
- Internal pipe lining.
- Instruction prefetch.
- Comprises dual Arithmetic and Logic Units allowing
up to 3 operand arithmetic operations to be
executed simultaneously.
- Extensive error checking with roll-back allowing
instruction reexecution.
- Designed for multi CPU, multiprocessor environment.
- Non-mapped and mapped virtual memory capability.
- Field exchangeable single unit.
2.3 H̲U̲M̲A̲N̲ ̲F̲A̲C̲T̲O̲R̲S̲ ̲C̲O̲N̲S̲I̲D̲E̲R̲A̲T̲I̲O̲N̲S̲
The system is designed to comply with modern man-machine
interface practice and with due considerations to operators
and maintenance personnel for minimal training, operational
knowledge, minimal computer system knowledge, and user
error tolerance. The system is also designed for unattended
operations to the widest possible extend. The primary
fields where human factors have been considered are
in operations and in maintenance.
2.3.1 O̲p̲e̲r̲a̲t̲i̲o̲n̲s̲
The system have been designed for operators with little
or no knowledge of computers by providing menu driven
function selection, both for the supervisory functions,
for the Message correction functions and for training.
Furthermore, where input is allowed or requested to
the operator the data is checked in type, range and
legality to the extent possible. The updates to the
tables are validated where possible and critical input
data must be validated by the operator after injection.
2.3.2 M̲a̲i̲n̲t̲e̲n̲a̲n̲c̲e̲
The system has been constructed for fast maintenance
with minimum training. The fault finding is heavily
supported by visual aids in the form of control LEDs
on all modules and by on-line and off-line diagnostic
programs.
The capability for on-line maintenance is described
in the preceeding section, section 2.2.
