GE DATANET-30 User guide

GENERAL ELECTRIC
COMPUTERS
CPB - 28 9 A I
I , !
DATANET-30
Systems Manual

DATANET-30
SYSTEMS MANUAL
July 1963
Rev. February 1966
GENERAL fl ELECTRIC
COMPUTER DEPARTMENT

PREFACE
DATANET is a General Electric registered trademark and is applied to GE products or systems
using public or privately-owned transmission facilities to permit the processing of information at
a point remote from its orgin. The DATANET-30 is a 128 channel data communications processor
which enables remote terminal facilities to communicate with other remote terminal facilities,
or a central information processing system.
This manual provides general information on DAT ANET-30 system configurations and on
DATANET-30 hardware, but will not include information on transmission lines, digital subsets,
remote terminal devices or other products included within a total communications complex.
Comments on this publication may be addressed to Technical Publications, Computer Department,
General Electric Company, P. 0. Box 2961, Phoenix, Arizona, 85002.
@1963, 1965 by General Electric Company
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Page
lliTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1. GENERAL SYSTEMS DESCRIPTION
Teletype Message Switching System ................................ .
Functions ......................................... · · · · · ·
Operation ..................•............................
Switching Center Size .......................................... .
Small Switching Center ..................................... .
Medium Switching Center ................................... .
Large Switching Center .......................•..............
DAT ANET-30 as a Remote Concentrator •.............................
Functions ......... ~ .................................... .
Operation •..............................................
'T'l-.r. l\T ,,.+.,,,..,..,..1,..
............ "" .&.''-'"'vw.....,,1..1. ..... • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
Functions .............................................. .
Operation •..........••.•.....•.......•..............•...
Communication/Data Processing Systems •....................•.......
Remote Inquiry . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote File Updating ..•....................................
Data Colle ct ion . . . • . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote Data Processing .................................... .
Tin1e Sharing ........................................... .
Equipn1ent Configurations ....................................... .
2. DATANET-30 COMPONENTS
5
5
6
7
7
8
9
10
11
11
11
12
12
12
12
12
13
14
14
14
General Description. . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . 17
Data Communications Processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Buffer Selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Channel Address ......... -, . . . . . . . . . . . . . . . . • . . . . • . . . . . . . . . . 18
DATANET-30 Buffer Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Other System Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
DATANET-30 to DATANET-30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
DATANET-30 Peripheral Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
EDP Center . . . . . • • . . . . . . . • . . . . . • . . . . . • • • . • . • . . . . . . • • . . . . 19
Communication Line Buffer. . . . . . . . . . • . . . • . • . . . . . . . • . . . . • . . . • . . . . . 20
The Bit Buffer Unit Module . . . . . . . . . . . . • . . • . . • . . • . . • . . • . . . . . . . 20
The Character/Word Unit Module (CWU 930) . . . • . . • . . • . . • . . • . . . . . . . 23
Character/Word Unit Module (CWU 931) . . . . . . • • . • • . • . . . • . . . • • . • • . 26
Character Buffer Channel (CBC 931). . . . . . . . . . . . . . . . . . . . . . . . . 26
Dialing Adapter Channel (DAC 930). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Configurations . . . . . . . . . . . . . . . . . . . . . . . . • . . . • . . . . . . . . . . . . . . 27
Controls and Indicators. . . . . . . . . . • . . • . . . . • . . . • • . . . . . . • . • • . . . . 27
Buffer Operations • . • • • . . . . • • . . • . . • . • . . . . . . . . . . . . . . . . . . . . . . 27
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Page
Automatic Calling Unit (ACU). • . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . 29
Interconnecting Computer Buffers . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Processor Interrupt Unit (PIU 930) . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . 29
Data Transfe:r: ................•........................... · 30
Controls and Indicators. . • . . . . • . . • . . . . • . . • . . . . . . . . . . . . . . • 30
Computer Interface Unit (CIU 931) . . . . • • . . . . . . . • . • . . . . . . . . . . . . • . . . . . 30
Data Transfer . . . . . . . . . . . • . . . . • • . . . . . . . . . . . . . . . . . . . . • . . . . . 31
DATANET-30 to the Computer Interface Unit . . . . . . . . . . . . . . . . . . . 31
External Computer to the Computer Interface Unit. . . . . . . . . . . . . . . • 31
Data Flow Through the Computer Interface Unit. • . . . . . . . . . . . . . . . . 31
Computer Interface Unit (CIU 930). . . . . . • • • • . . . • . • • • • . . . . . . . . . . . • . . . . 32
Data Transfer . . . • . . . • . . . . • . . . . • . . . . • . . . • . . . . . . . . . . . . . . . . . 32
Receive Sequence. . . . . . . . . . • • . . . . . . • . . • . . . . . . . . . . . . . . . • 33
Transmit Sequence. . • . . . . . . • • . . . . . . . . . . . • . . . . . . . . . . . . . . 33
Peripheral Equipment Buffers . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . 34
Controller Selector Unit . . • . . . . . . . • . . . . • . . • . . • . . . . . . . . . . . . . . . 34
Common Peripheral Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Data Transfer . • . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . 35
Peripheral Equipment Information. . . . . . . . • . . . . . . . . . . . . . . . . . . 35
RDC 930 Removable Disc Storage Subsystem . . • . . . . . . . . . . . . . . . . . . . . . . . . 36
Removable Disc Unit Module (RDU 930) . . • . . . . . . . . . . . . . . . . . . . . . . . . 36
Controls and Indicators. . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . 36
Memory Interrupt Cycle Assignment. . • . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Additional Storage Unit (ASU 930) . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . 37
Extra Removable Disc Cartridge . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . 37
Card Reader Unit. . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Ptu1ch Reader Unit. . . . . . . . . . . . . . . . . . . . . . . .• . . . . . . . . . . . . . . . . . 38
Other System Components. . . . . . . . . . . . . • . . . . . . . . • . . . . . . . . . . . . . . . . . 38
The GE-200 Series Peripheral Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Console Unit. . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Sv.ritch Units . . • . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . 39
Programmed Peripheral Switch . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . 39
The GE-400/600 Series Peripheral Switch . . . . . . . . . . . . . . . . . . . . . 40
Parallel Channel Adapt. . . . • . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . 40
The DATANET-30 with a GE-115 System.......................... 41
DATANET-760 Keyboard/Display Terminal System. . . . . • . . . . . . . . . . . . . 41
Systen1 Configuration . . . . . . . . • • . • . . • • . • . . • . . . . . . . . . . . . . . 41
Summary of DAT ANET-30 Components . . . . . . . . . . • . . . • . . . . • . . . . • . . . . . . 42
Summary of Buffer Modules . • . . . . . . . . . . . . . • • . . . . . • . . . . • . . . . . . 42
Summary of Transmission Speeds, Code Levels, Input/Output. . • . . . . . . . . . 43
3. DAT ANET-30 PROCESSOR-DETAILED DESCRIPTION
Functional Seql1ence. . • . . . . . . . . . . . . . . . . . . . . • . • . . . . . . . . . . . . . . . . . . 45
Block Diagram • • . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Representation of Information in Memory. . . . . . . . . • • . . . • . . . . . . . . . . . . . . . 47
Alphanumeric Data Words. . . • . . . . . . . . . . . . • . . . • . . . . . . . . • . . . . . . 47
Nun1eric Data Words. . . • . . . . . . . . • . . • . • . . . . . . . . . . . . • . . . . . . . . 47
Special Data Words • . . • . . . . . . . . • . . • . . . . . . . . . . . . . . . . . . • . . . . . 49
Instruction Words Format. . . . . . . . • • . . • . . . . . . . • . . . . . . . . . . . . • . . 50
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iv

Detailed Block Diagram ...••....•.•..•......•...•...............
Description of Blocks .•••••...••.•.....................•.•..
The Memory Unit ..•.•••.......•.•.....••..•...........
The Buffer Selector ..•.••••...........••....•.....•....
The Controller Selector .••.•...•........................
Parity Network (21 no abb., N) ..•...••.••.•..•............
Hardware Load and Paper Tape Reader • • • . • . • • . • . • . . • • . • . . . . . • . . . . . • .
Hardware Scan . . . . . • . • • • . • • • • • . • • . • • • . • • • • . . . . . . . . . . . . . . .
Elapsed Time Clock ...••.•.•••••••••..•.•.••••••.•..•.....•...
Line Service Rate .....•.•.••.••.••....•..•••.•..•.•.....•.....
Basic Program Cycle .•••..••.•••...••......••.•......••...•..••
Addressing Memory .•.....•••.•...•••••..•.•.•.•••.•....•.....•
Direct Access to a Program Bank .•.•....•.•••.•.......•..•....
Direct Access to the Common Data Bank •....••.•.••.......•......
Direct Access to a Channel Table ••..•...•.....•••..•.......•...
Indirect Addressing .•.•••.•.•..••.••....•........•....•....
Indirect Access from a Program Bank •.•...••.•.•....•..........
Indirect Access from the Common Data Bank .•••...•.•.......•.....
Indirect Access from a Channel Table ......••••..................
Interrupt Interface. . . . . . • . . • . . • • • • • . . • • . . . • . . • • • . . . . . . . . . . . . . . •
AllocaLiuu of Cy Cle s. • • • • • • • • • • • • • • • • • • • • • • • • • • . • • . . . . . . . . . -
Control Console ...•.••••.•..•••••••••.....•...•.•••.•••......
4. PROGRAMMING
Program Preparation. . • • • . • • • • . . . • • • • • • • • . • • . • . • • . . • • . . . • . ..••.
Assembly Programs ..•••••••••••••••.••.•..•.•••••.••..•••
Programming Aids .•..•..•••.•.•.••.•.•.•••••..•.•.•..•.••
Utility Routines • • . • • • • • . • • • . • • • • . • . . • . • . • • • • • • . • . • • • . . •.•••••
Diagnostic •.•.•..•••••••••••.••••..•••••••••••••..•••.••
System Programming Considerations ••••••.••...••••••.••••.••••
Message Switching Center •••••••••••••.•••••••••...•.••••••••
Intergrated Data Processing •••••.•••••••••••••••••••••.•.••••
Instruct ion Repertoire • • • • • • • • • • • • • • • • • • • • • • • . • • • • • • • •·• • • . . . • • • •
Load Instructions ••••..••••••••••.••.••...•••••.••••••
Store Instructions •••••••••••••••••••.•••••••••••••..••
Arithmetic Instructions • • • • • .• • • • • • • . • • • • • • • • • • • • • . • . . • . •
Logical Instructions •••••••• · •.•••.•.••••••••.•.••••.•...
Register Transfer Instructions •••••••.•.••••••.••.•••••.••
Branch Instructions •••••••.•••••••.••••••••••.•••••..•••
Special Instructions .••••.••.••.•••••••••••••••••.•.••..
Buffer Selector Instructions •.•••••••••••••••.•....•••.•.•
Controller Sele ct or • . • • • • • • • • . • • . • • . • • . . • • • • . • • • . • • • . . • • • . •
Installation Information ....••••••••.••.•.•..•••..•..•••....•...•
Components Sizes .••.•.••••••.•..•••..•••••••..••...••.•.•
Electrical Requirements ••.••.•••..•..•.•.•.•••.......•.•.•.
Environmental Requirements .....••••.••....••..•.••...••....
Ventilation • • • • • . . . • • . . . • • • • • • . • . . . . . . . • . • • . • • • • • . . . . . • . .
Cables to Communication Line Interface .••.••••••••••••.......••.
Controller Selector Cables • • • • • . . • • • • • • . . • • . • . • • • • • • • . . • • • . . .
INDEX ................................................... .
Page
52
54
56
56
57
57
57
58
58
58
59
60
60
60
60
60
61
61
61
61
62
62
67
67
68
68
68
68
69
70
70
71
71
72
73
·74
77
78
79
80
80
80
80
80
81
81
81
83
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Figure
Page
1. DAT ANET-30 Processor . • . • . • . . . • • • . • • . • • . . • • . . . . . . . . . • . . • . 2
2. System with RDC 930 Units • • . . • . . • • • . . . • . • . • . • . . . • . . . • . . • . • . . 7
3. Medium Switching Center. . . . • . . . . . . . . . • . . . . . . • . . . . . . . . . . • . . • . 8
4. Large Switching Center. • . . • • . . . . . . . . . . . • . . . . . . • . . . . . . . . . . • . • 9
5. Communication Lines with a Remote Concentrator . . • • . . . . . . . . • . • . . • . 10
6. Nationwide Network . . • . . . • • • . . . . • • . . . . . • . . . • . . . . . • . • . . • . . • . 11
7. Remote File Updating • . . . . . • . • . • . . . • • . . . . . • • . . . . . . . . . • . . . . . 13
8. Data Collection • . . . . . . . • . . . . . . . . . . . • . . . . . . . . . . • . . . . . . . . . . . 13
9. Remote Data Processing . . • . • . • . . • . . • . . . . . . • . • • . . . . . . . . . . . • . . 14
10. DATANET-30 System Components--Not a Typical System. • • . . . . • • . . . . . . 15
11. Bit Buffer Module. . . • • . . • . • . • . . • • . • • . . . . . • • • . • • . . . . . . . . . . • . 20
12. Receive Mode . • . • . . . . . . . . . . . . . • . . . . • . • . . . • . . . . • . . . . • • . • • . 21
13. Transmit Mode . . . . . • . . . • • . • . . • . . . . . . . • • . • • . . . • . . • . • • . . • • • 22
14. Echoplex Mode . . • . • . . • . • . . • . • • . . • • . . . . . . . . . . . . • . • . . . . . • • . 22
15. Character/Word Buffer Channel • . • . • • • . . • . • • • . • . . . . . • . . . • . • . . . . 23
16. Character Buffer Transmit and Receive . • • • . . • • . . • . . • • • • . • • • . . • • • 25
17. Word Buffer Channel Transmit and Receive • • • • • • • • . • . • • • • • • . • • • • • • 25
18. Character Buffer Channel Block Diagram. • • • • . • • • • • • . . • • . • • . • • . • • . 26
I
19. Dialing Adapter Units with Telephone Equipment and Bit Buffer • • • • • • • • . • • 28
20. Dialing Adapter Units with Telephone Equipment and Character
or Word Buffers • • • • • • • • • • • • • • • • • • • • • . • • • • . • . • • • . • • . • • 28
21. PIU Connecting Two DATANET-30's. . • • • • • • • • • • • • • • • • • • . • • • • • • • • 29
22. CIU 931 Connecting a DATANET-30 with an External Computer. • • • • . • • . • • 30
23. Data Transfer Through a CIU 931 • • • • • . • . • . . • • • • • . • • • • . . • • • • • • • • 31
24. CIU 930 Connecting a DATANET-30 and a GE-200 Series Computer • . . • • • • • 32
25. DAT ANET-30 with Controller Selector Unit and Peripheral
Equipment • • • • • • • • • • • • • . • • • • • • • • • • • • • • • . • . . . . . . • • . . . 34
26. CPC Peripheral Equipment . • • . • . • • • • • . • • • • • • • • . . • • . • • • • . . • • • • 35
27. DAT ANET-30/RDC 930 Block Diagram • • . • . . • . . • • • • • . . • . • . • . • • • • . 36
28. DAT ANET-30 with a Card Reader. . . • • • • • • • . . . • . • . • . . • . . . • • . • . . . 37
29. DATANET-30 with Card Punch and Reader Units. . • . . . • • . . • . . . • . • • • . • 38
30. Typical PS-6010 Switch Application. . . . • . • . . . . • . • . • . . . . . . . . . . . . . . 39
31. Parallel Channel Adapter Block Diagram • • . • . • . . . • . . • . . . . . . . . . . . . . 40
32. DAT ANET-760 Display System. • • • . • • . . • • . • . . . . . • . . . . . • . . . . . . . . 41
33. Data Flow Functional Block Diagram. • . . • . • . • • . • • . . . . . . . . . . . . . . . . 45
34. Simplified Block Diagram • • • • • • • . • • . • • • . • • . • • . . • . . . . . . . . . • • . . 46
35. Detailed Block Diagram DATANET-30. . . . • . . • . . . • . . . . . . . . . • . . . . . . 53
36. The Control Console. . • . • • . • . • . . • . . . . • . . . . . • . . . . . . . . . . . . . . . . 63
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vii

INTRODUCTION
With the trend toward more decentralization of company operations over a wider geographic area,
with more products to sell to more customers, there is also the trend to centralize management
of company operations. In order to make the right decision at the right time--of what to build,
what materials to buy, how much of an item to ship to an area warehouse, what type of an inven-
tory to maintain and the many other involved problems of a far flung modern business--the
managers who make these decisions must have accurate data that represents the situation at the
moment--today--not last week.
For effective control, management requires timely and accurate information which reflects the
decisions on the total business environment. For example, better customer service, with shorter
lead time on orders received and faster answers to inquiries is often the determining factor in
where an order is placed.
Tne requirements for this unified systems approach io mana~emeu( aud l::Usto.r.ne:r service take; ou.
added significance when one considers the size of the communications problem in business oper-
ations. The continued growth of business, increased specialization, and decentralization have
created many barriers to the flow of information. Undoubtedly the most formidable communications
problem is the sheer volume of information to be handled.
Concurrent with the need for timely and reliable information, another requirement developed. The
trend toward decentralization created the need for data processing at district locations which, in
many cases, is not economically iustified. Hence, management must rely on a centrally located
computer to handle the processing load for each district--a practice which again poses a problem
in communications.
The development of computer-based data communications networks has progressed to the point
where it is economically feasible to transmit data over public carrier facilities. New services
and reduced rates are offered for transmission of digital data. In order to take advantage of these
developments, and at the same time satisfy many needs in business communications, General
Electric developed the DATANET-30.
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-1-

11
11
I I
.> .> > •• · ···
.........
......
Figure 1. DATANET-30 Processor
··· - ~ .
. .....
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1. GENERAL SYSTEMS DESCRIPTION
The DATANET-30 is a real-time computer--designed primarily to automatically receive and
process information originated at locations remote from the central computer (remote terminals)--
and to automatically transmit information to the remote terminals over normal common carrier
communication facilities.
The DATANET-30 is:
• High speed
• Solid state
• Single address
• Special purpose
• Communications oriented
• Digital computer
1_ ---
Ui::l.::>.
• A binary mode of operation
• A 7 microsecond word time
• A stored program
• A magnetic core memory
• Over 78 basic instructions
• 18-bit word in memory
• Up to 128 input/ output channels
• Memory interrupt
• Indirect addressing and multiple indexing
• An elapsed time counter
• Patch plug adaptability to character and word length
• Patch plug adaptability to transmission and receiving speeds
performs:
• As central control for a DATANET-30 communication system
• As a communications controller for a GE-200, 400 or 600 Series General Purpose
Computer
• Arithmetic and data manipulation operations
• On a real time basis
capable of:
• Controlled transmission of data over common carrier facilities
• Serving as a communications control between remote terminals and a computer
• Unattended operation
• Using a variety of remote terminal devices including Teletype keyboard printers, a
computeral DATANET-760 Terminal
• Simultaneous transmission to remote terminals
[ID£1J£~~1YCJ ~®------------
-3-

• Simultaneous receiving from remote terminals
• Receiving and transmitting digital data over Teletype or telephone grade transmission
lines--private or leased--or public dial-up services, manual and automatic
• Operating with 5, 6, 7, 8, level codes, and other codes up to 20 bits
• Operating at standard transmission/ receive speeds (in bits per second} of 45; 50; 56. 25;
66. 2; 72. 6; 75; 110; 150; 300; 600; 800; 1050; 1200; 1800; 2000 and 2400
• Storing and retrieving data on a disc storage unit
• Storing and retrieving data on magnetic tape compatible with a computer
• Printing reports on a high speed printer or Teletype machine
performs the functions of:
• Message assembly
• Message formatting
• Message disassembly
• Message scheduling
• Multiple message broadcast
• Store and forward communication
• Communications network control
• Control of switched network lines
• Message accounting and traffic analysis
• Producing traffic statistics
• Basic message routing and switching
• Handling priority messages
• Handling variable message lengths
• Maintaining a high line loading
• Journal keeping
• Alternate routing on a station or center basis
• Inserting time and date
• Message acknowledgment
• Control of multipoint private lines
• Code conversion
• Speed conversion
• Format control and conversion
• Providing cost allocation on message or station basis
• Error control--operator and code
• Character and word parity checking
• Automatic program reload
• "End of Transmission" and "End of Text" code detection under program control
The capability to receive the transmission of data from remote terminals allows a DATANET-30
system to perform as a:
• Message switching center where messages and data are going from one remote terminal to
another
• Remote data processing where data from remote stations is processed at a central com-
puter, and as needed, reports are sent to remote stations. The DATANET-30 can be
programmed to handle data traffic for a data processing center with equal facility that
it handles the administrative traffic normally associated with telegraph switching centers
• Remote inquiry where an answer is generated by the computer and transmitted to the
station requesting
• Automatic data accumulation and distribution to/from a variety of points for batch pro-
cessing by a computer
• File updating where reports from remote stations are processed by a central computer
on a batch process basis
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A DATANET-30 system consists of a variety of equipment, the choice of which depends upon sys-
tem design and requirements. The following illustrations cover some of the combinations possible
with a DA TANET-30 to fill the communication requirements of modern business activities.
TELETYPE MESSAGE SWITCHING SYSTEM
The General Electric DATANET-30 switching center is a fully-automatic system designed to
perform, store and forward message switching. The DATANET-30 switching center can be used
to communicate with any of the following:
1. Direct-connected communication stations,
2. Multipoint private line connected stations,
3. Dial-up stations on public message networks,
4. Direct input/output with computer systems (core to core),
5. Indirect input/ output with computer systems (via magnetic tape or a disc storage unit),
6. Communication with other networks or portions of a network.
Functions
All the functions of transmitting to or rece1vmg messages (data) from a remote terminal, and
handling the messages enroute from origin to destination must be coordinated within the message
switching system. This coordination is accomplished by providing means for the functions of:
1. Message Accumulation--Messages are assembled and routed under program control.
2. Message Distribution--Messages are distributed under program control.
3. Automatic Multipoint Private Line Control (Party Line)--Polling and selection of stations
on the line is accomplished under program control.
4. In-Transit Storage--Storage is provided for message queueing.
5. Journal Storage--Storage is provided for recording message journals.
6. Intercept Storage--Storage is provided for messages for stations closed due to limited
time of operation, station malfunction, etc.
7. Message Accounting--Journal storage can be processed during off hours or low activity
periods to provide daily status reports, and data for network study.
8. Traffic Analysis--The number of messages per line per station per day can be counted.
The reports generated can then by typed out at the supervisory position. Such items as
average message length, number of multiple message broadcasts, and operator errors in
formatting may be included in the reports.
9. Multiple Message Broadcast--Individual messages can be routed to more than one out-
station as designated by the routing indicators.
10. Automatic Restart--System is capable of automatically restarting itself in case of
program malfunction.
11. Supervisory System Monitoring--One Automatic Send-Receive (ASR) and a Receive Only
(RO) Teletype device are used for system monitoring. Headers of misrouted messages
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can be printed out and corrected. The supervisor can send service messages to open or
close out stations and/ or to send data to intercept storage.
12. Format Conversion--Changing the order of spacing of data from the incoming order to the
desired outgoing order.
13. Error Control--A variety of error detection and correction schemes can be used. Oper-
ator error codes can be recognized and a recovery or re-start procedure set up for that
message. The DATANET-30 can be programmed to control the format of a message and
notify the operator of any format errors. Also, transmission errors can be recognized
through echoplex retransmission. Parity check of codes and block parity checks can be
used.
14. Alternate Routing of Messages--Supervisory changes in routing on a temporary basis in
case of line or terminal outage. Programmed automatic alternate routing is also possible.
15. Priority Messages--Messages may contain a "Priority Level Code" that can be recog-
nized by the DATANET-30 program. Thus hot messages or data can be handled before
routine administrative messages.
Operation
The operation of the switching center is fully automatic--under control of the program. The
sequence of transmission of terminals on a multipoint private line is also controlled by the pro-
gram. Each message contains a destination code--the name or number of the remote station
or stations where the message is going. After a message is received from a remote station, the
program interrogates the destination code of the message in memory, then transmits it to the
proper remote terminals. The DATANET-30 is programmed to handle all normal messages in
accordance with a standard format and standard routing codes for the system. A standard
incoming message format would be used for all incoming traffic, including rush messages, normal
messages, and service or control messages. The distinction between messages is made by the
mnemonic address code.
The system is capable of operation with only occasional manual intervention and control. The con-
trol is accomplished through the supervisory terminal to open and close stations by time of day
and enter other control messages. When a station is closed, the program forwards all messages
for the closed station to intercept storage.
The supervisory terminal normally consists of a keyboard/printer Teletype unit. This terminal
is used as a message intercept position for incorrectly routed or formatted messages. The super-
visor looks at the messages and decides what action is necessary, such as, correct the heading
and re-enter the message, ask for retransmission, etc. The terminal is also used to notify the
supervisor of line malfunctions and for printing out periodic status reports on the switching
center operation.
The detailed operation of each system will be developed according to individual system require-
ments, such as; routing, service and control codes, format, number of lines and remote terminals,
and the many other overall system operational requirements.
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SWITCHING CENTER SIZE
The number of communication lines to be connected to the DATANET-30 permits a broad defini-
tion for the size of a switching center and associated equipment. A switching center can be defined
as small, medium or large.
Small Switching Center
A small switching center would have an RDC 930 Removable Disc Unit and up to 10 communica-
tion lines of half duplex or full duplex operation. The amount of traffic is assumed to be in the
range of 1 million characters per day throughput. The RDC 930 Removable Disc Unit is especially
adaptable to this size system.
DATANET-30
RDU 930
Bit Buffer Units
Figure 2. System with RDC 930 Units
0
0
ASU#l
ROC 930
Removable
Disc
Units
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Medium Switching Center
The medium switching center would have an M225B Disc Storage Unit and up to 30 communication
lines of half duplex or full duplex operation. The amount of traffic is assumed to be in the range
of 4 million characters per day throughput. The M225B Disc Storage Unit provides the capacity
to operate this size system efficiently.
Supervisory
Position
DATANET-30
LJ-~··
Keyboard/Printer
Remote Station
CONTROLLER
Storage for
Queue, Intercept and
Journal Ledger
.QLJ
LLJ
DISC
STORAGE
UNIT
Keyboard/Printer
Remote Station
Figure 3. Medium Switching Center
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Large Switching Center
The large switching center would have more than one DATANET-30, one or more M225BX Disc
Storage Units with Dual Access Controllers, and more than 30 communication lines. The com-
munication lines would be of half duplex or full duplex operation with up to ten stations per line,
or private line. The amount of traffic is assumed to exceed 10 million characters per day
throughput.
DATANET-30
CSU
PIU
Bit Buffers
Dual
Access
DSU
Figure 4. Large Switching Center
DATANET-30
CSU
PIU
Bit Buffers
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DATANET-30 AS A REMOTE CONCENTRATOR
When many remote stations are located many miles from the DATANET-30 switching center, it
may be desirable to include one or more DATANET-30's to act as a concentrator for the more
distant remote terminals. This will reduce the number of long distant lines coming into the
switching center.
The remote concentrator is connected to the switching center via a "high speed" voice-quality
trunk line. The DATANET-30 can "pack" many messages received at slow speed (75-110 bps) and
transmit them. There are two main advantages:
1. Where the switching center would be overloaded if all remote terminals were directly
connected, the use of the remote concentrator will reduce the time delay in a message
from its origin to its destination. This is especially so if the remote stations were
connected by multipoint private lines since it would then be possible to connect them via
single lines on the remote concentrator.
2. Reduction in transmission line costs. If all remote stations were directly connected,
there would be many "parallel" telegraph lines; whereas with the remote concentrator,
there is one voice line.
Switching
Center
Figure 5. Communication Lines with a Remote Concentrator
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Functions
As a remote concentrator, the DATANET-30 takes traffic from low volume areas with low speed
terminal devices and depending upon the program, performs the following functions:
1. Message accumulation and distribution
2. Code conversion
3. Speed conversion
4. Multipri vate line control
5. Error control
6. In-transit storage
7. Unattended operation
Operation
The messages are accumulated from many remote terminals and held in the in-transit storage
until they can be transmitted at higher speed over a trunk line to a DATANET-30 switching center.
When messages are received by a DATANET-30 remote concentrator from another DATANET-30,
speed and code conversion are accomplished and the messages are transmitted out to the lower
speed terminal devices. Hence, an increase in line utilization is obtained between two DATA-
NET-30 centers and the low speed remote terminals. Traffic can be handled two ways:
The concentrator can act as a store and forward switching center between those remote
terminals connected into the concentrator.
The concentrator can be operating in the capacity of a relay station with the message switching
being done by a DATANET-30 functioning as a switching center. All messages would go one
way to the switching center and then back to the concentrator for transmission to one of the
remote stations.
THE NETWORK
The DATANET-30 can be built up to a network configuration by interconnecting several DATA-
NET-30 switching centers with high speed lines.
Figure 6. Nationwide Network
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