IBM 2790 User manual

File No. 2790-09
Order No. GA27-3015-1
Systems Referen e Library
Component Des ription!
IBM 2730 Data Communi ation System
The IBM 2790 Data Communi ation System is a two-way ommuni ation
and produ tion reporting system. This publi ation des ribes the 2790
system units along with its apabilities, features, and appli ations. This
publi ation presumes a tele ommuni ations ba kground and IBM
System/360 experien e. The purpose of this publi ation is to assist
programmers and systems analysts in designing and operating the 2790
system.
This publi ation des ribes the 2790 system using the 2715 Transmission
Control Unit as the system ontroller. The IBM 1800 Data A quisition
and Control System, whi h ould also be used as the system ontroller,
is not des ribed in this manual. Information about the following units
is in luded in this publi ation:
IBM 2715 Transmission Control Unit IBM 2796 Data Entry Unit
IBM 2791 Area Station IBM 1035 Badge Reader
IBM 2793 Area Station IBM 1053 Printer
IBM 2795 Data Entry Unit
The following IBM publi ations are re ommended for use with this
manual:
IBM 35 7/1030/2 790 Badge Specifications, GA21 -9028
IBM System/360 Bib iography, GA22-6822
IBM Te eprocessing Bib iography, GA24-3089
IBM 2740 Communications Termina : Component Description,
GA24-3403
IBM 2740/2741 Communications Termina -Operator's Guide,
GA27-3001
IBM System/360 Operating System, Basic Te ecommunications
A ccess Method, GC 30-2004
IBM System/360 Disk Operating System, Basic Te ecommunications
Access Method, GC30-5001
IBM System/360 OS/DOS P anning for Improved BTAM Support o f
Remote BSC Stations, GC30-1005

Preface 2790 SRL Publications Availability Guide
This manual des ribes the IBM 2790 Data Communi ation
System with the IBM 2715 Transmission Control Unit as
the system ontroller. For information about the IBM
1800 system used as a system ontroller, see Systems Ref
eren e Library manual, IBM 1800 Data Acquisition and
Contro System Functiona Characteristics, GA26-5918-7
(with TNL N26-0241) or later edition.
Before using this manual, you should have a ba kground
in tele ommuni ations and experien e in using the IBM
System/360. This manual is designed for use as a ompre
hensive referen e manual by programmers and systems
analysts. Information about the following 2790 system
units is presented:
IBM 2715 Transmission Control Unit
IBM 2791 Area Station
IBM 2793 Area Station
IBM 2795 Data Entry Unit
IBM 2796 Data Entry Unit
IBM 1035 Badge Reader
IBM 1053 Printer
For information about programming the System/360
to operate with the 2790 system, see Systems Referen e
Library manuals: IBM System/360 Operating System,
Basic Te ecommunications Access Method, GC30-2004;
IBM System/360 Disk Operating System, Basic Te e
communications Access Method, GC30-5001; and IBM
System/360 OS/DOS for Improved BTAM Support o f
Remote BSC Stations, GC30-1005.
Manuals related to this publi ation are referen ed in the
Publi ations Availability Guide.
I
Second Edition (March 1970)
This is a major revision of, and obsoletes, G 27-3015-0. Significant new material
has been added throughout, and existing material has been changed extensively;
therefore, the entire manual should be reread.
Changes are periodically made to the information herein; any such changes will
be reported in subsequent revisions or Technical Newsletters.
This manual has been prepared by the IBM Systems Development Division, Publi
cations Center, Department E01, P.O. Box 12275, Research Triangle Park, North
Carolina 27709. form for reader’s comments is provided at the back of this
manual. If the form has been removed, comments may be sent to the above address.
©Copyright International Business Machines Corporation 1969, 1970

Contents
Introduction
Typical pplications ..............................
ttendance Recording ........................
Material Control ....................................
Production Control ..............................
Data Entry U n i t s
2795 Data Entry U n it ..............................
Badge-Card Reader ..............................
2795 Data E n t r y ..............................
Selection S w it c h ..............................
Phone J a c k ..........................................
Error Indicator/Reset Button .
Request L e v e r ....................................
2796 Data Entry U n it ..............................
2796 Data E n t r y ..............................
Data Entry Unit Transaction Selection .
Transaction Expansion ........................
Area S t a t io n s
2791 rea S tation ....................................
Transmission Capability .
Card Reader ..........................................
Badge R e a d e r ....................................
Transaction Selection Switches
Control K e y s ....................................
Manual E n t r y ....................................
Visual D isp la y ....................................
Operator Guidance Panel .
rea Station ddresses ........................
2791 Data E n t r y ..............................
dapters ................................................
2793 rea S ta tion ....................................
IBM 2715 Transmission Control Unit
2715 TCU F un ction s ..............................
Models of Operation with System/360
2715 Machine Features ..............................
Standard Features for Models 1 and 2
Selective Features for Models 1 and 2
Selective Features for 2715 Model 1 .
Selective Features for 2715 Model 2 .
Configuration Parameters .
2715 General Characteristics .
Multiplexer Channel dapter (Standard on
2715 Model 1 ) ...............................................................................31
C om m ands.................................................................................... 32
Binary Synchronous Communications dapter
(Standard on 2715 Model 2 ) .......................................................33
Real-Time Clock ( R T C ).............................................................35
Day Number .................................................................................... 35
CE/Operator P an el .............................................................................. 35
2790 d a p ter.....................................................................................39
Data-Handling C a p a c ity .............................................................39
2715 Operational Characteristics ...................................................... 40
Data Management ........................................................................ 40
Data Format.................................................................................... 41
2715 Control Requests .................................................................. 43
2790 ERP Message F o r m a t ...................................................... 53
Restart-Number L oggin g ............................................................ 54
Core Storage.................................................................................... 54
System/360 R e se t ........................................................................ 54
2715 Performance........................................................................54
Error P roced u res.............................................................................. 57
Error at the 2795/2796 Data Entry Unit or 1035
Badge R eader.................................................................................... 57
Error at the 2791 rea S t a t io n ................................................57
I
Length C h e c k ........................................................................57
Digit C heck.................................................................................... 58
Other 2790 Transmission Line Error Checks .... 58
Error at the Transmission Control U n it ...........................................58
2715 Error Recording .................................................................. 58
2715 D iagn ostics ........................................................................ 59
Multiplexer Channel Error Recovery Procedures . . . 59
Programming Considerations ............................................................ 61
System O peration...............................................................................61
OS and DOS S u p p ort...............................................................61
| User Job Planning F o rm s .................................................................. 62
rea Stations and Data Entry Unit Table (Figure 32) . . 62
Transaction Group Table (Figure 3 3 ) ..................................... 64
Transaction List Table (Figure 3 4 ) ........................................... 64
Glossary................................................................................................71
Index ........................ 73
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Illustrations
Figure Title
1 Typical 2790 Data Communications System .
I 2 IBM 2790 Configuration ................................................
3 IBM 2795 Data Entry U n i t ..........................................
4 IBM 2796 Data Entry U n i t ..........................................
| 5 DEU Badge and 80-Column Card Punch Information .
6 2795 Data Entry as ssembled in the 2715 TCU
7 2796 Data Entry as ssembled in the 2715 TCU
8 Segm entation..................................................................
9 IBM 2791 rea Station......................................................
10 cceptable rea Station Character Set and Card Code .
11 Operator P a n el...................................................................
| 12 Sample L e tterin g.............................................................
13 2791 Data Entry as ssembled in the 2715 TCU
14 IBM 1053 and 2740 Printer Character Set . . . .
15 Loop ttachment and Shift Register ..............................
16 IBM 2793 rea Station ......................................................
17 IBM 2715 Transmission Control U n i t ........................
18 Line Transfer S w itc h ......................................................
Figure Title Page
19 Line Transfer Switch-Third U nit..................................29
20 Point-to-Point Line Initialization Examples .... 33
1
21 Multipoint Line Initialization Examples........................34
22 CE/Operator P anel............................................................36
23 Transmission Line Utilization C hart ............................. 38
24 Transaction Control B y t e ................................................41
25 Message Format-System/360 to 2740/1053 . . . 43
26 Message Format- S or DEU to 1053 44
27 Control R e q u e sts ........................................................... 45
28 Example 2740 P r in to u t................................................47
29 Read Deferred Data and Reinitialize Disk Sequence . 51
30 Example 2740 Printout of an Unsoliciated Message . 53
31 Simplified Example of User T a b l e ..............................65
32 S and DEU Table F o rm ................................................66
33 Transaction Group Table F o r m ................................... 67
34 Translation List Table F o r m ......................................... 68
35 Data Entries........................................................................69
Page
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IV

Introduction
Manufa turing fa ility management’s need to redu e oper
ating ost through more immediate awareness of the status
of plant operations is in reasing. The IBM 2790 Data Com-
| muni ation System (Figure 1) is a two-way data ommuni
ation and produ tion reporting system. It is a highly
flexible two-way data ommuni ation system designed to
meet the expanding requirements for in-plant data ommu-
| ni ations and produ tion monitoring. The 2790 system
provides for rapid transfer of information from various area
stations (AS’s) and data entry units (DEU’s) to a entral
omputer for re ording, pro essing, and analyzing.
The AS’s a ept alphameri data from standard
80- olumn pun hed ards; they a ept numeri data from
pun hed identifi ation badges and manual entry units. The
DEU’s a ept ten positions of numeri data from pun hed
| ards or pun hed badges; they also a ept information from
manual entry units. The AS and DEU information is trans
mitted by area stations to a transmission ontrol unit
(system ontroller). The transmission ontrol unit (TCU)
ommuni ates with an IBM System/360 via a lo al (multi
plexer hannel) or a remote (binary syn hronous trans
mission line) atta hment.
Either an IBM 2715 Transmission Control Unit or an
IBM 1800 Data A quisition and Control System with an
1800/2790 Adapter may be used as the system ontroller
for the 2790 system. For further information about the
IBM 1800 performing as the system ontroller, see Systems
Referen e Library manual, IBM 1800 Data Acquisition and
Contro System Functiona Characteristics, GA26-5918-7,
with TNL N26-0241, or a later version.
The IBM 2790 system onfiguration onsists of a entral
pro essor (IBM System/360), a transmission ontrol unit
(IBM 2715), area stations (IBM 2791 or IBM 2793), data
entry units (IBM 2795 or IBM 2796), and other I/O devi es.
The 2790 system onfiguration onsists of as many as 100
AS’s onne ted in a loop onfiguration, starting and ending
at the TCU. Adja ent units of the 2790 Data Communi
ation System are onne ted by a twisted-pair able (ex ept
the IBM 1035 Badge Reader and IBM 1053 Printer whi h
atta h to the area station by multiwire able). For example,
the units may be installed at intervals of 1000 feet by using
#22 AWG twisted-pair wire, or up to 4500 feet by using
RG 130/21 oaxial able (Figure 2). DEU’s an be atta hed
to an AS. Conne tion between a DEU and an AS is estab-
Data Entry Units
Figure 1. Typical IBM 2790 Data Communication System
Introduction 5

Up to 100 Area Stations
Up to 1024 Data Entry Units
Up to 32 Data Entry Units per 2791 Model 1 or 2793 Area Station
Up to three 1035 Badge Readers per 2791 Model 1 Area Station
One 1053 Printer per 2791 Model 1 or 2793 Area Station
| Up to 35 Area Stations per segment
Up to 1000 wire feet of two-wire communications line between Data Entry Units and Area Stations (No 22 AWG Twisted Pair) or 4500 feet using RG1 30/21 Coaxial Cable
Up to 1000 wire feet between Area Stations or between 2715 and Area Stations (No 22AWG Twisted Pair) or 4500 feet using RG130/21 Coaxial Cable
| See the Installation Physical Planning Manual GA27-3017-1 or later version for distances with other wire sizes
• Figure 2. IBM 2790 Configuration
I
lished by a two-wire ommuni ations line whi h may also
be up to 4500 feet. No lo ally supplied power is required
at the 2795 and 2796 Data Entry Units.
The IBM 2790 Data Communi ation System supplies
the latest information to the data pro essing enter, thus
diminishing the time gap between the organization of data
and its availability for use.
Some of the appli ations of the 2790 system are:
Produ t Control
Material Control
Labor Control
Tool Control
Quality Control
Attendan e Re ording
The advantages of the 2790 system over previous data
olle tion systems are:
6
1. The 2790 system is apable of high-speed data
transmission (approximately 900 hara ters per
se ond partitioned among the a tive terminals
on the loop).
2. Guidan e lights on the 2791 Area Station inform
the operator of the next operation the system
ontroller expe ts.
3. The 2790 system has the ability to ontrol a large
number of devi es (up to 100 area stations, 1024 data
entry units, 100 IBM 1053 Printers, and 300 IBM 1035
Badge Readers).
4. The DEU’s are inexpensive, an be atta hed to the
AS by a two-wire ommuni ations line, and require
no lo ally supplied power.
TYPICA L APPLICATIONS
The following dis ussion illustrates a 2790 system perform
ing typi al appli ations in a manufa turing plant.

Attendance Recording
The IBM 2790 system may be onfigured in two ways for
attendan e re ording. Where high-rate attendan e re ording
is required, the IBM 2791 with either the resident badge
reader or remote IBM 1035 may be used to provide a re ord
of the employee’s man number. (The system automati ally
inserts the time and lo ation into ea h transa tion.)
In other appli ations (with lower required entry rates),
the IBM 2795 or 2796 may be used.
Material Control
When raw material, pur hased parts, or assemblies are with
drawn from sto k, the IBM 2790 system provides an up-to-
date re ord of material on hand. A 2795 DEU or 2796 DEU
is installed in ea h sto k room. A prepun hed ten- olumn
ard or badge ontaining a file-re ord identifier for su h
information as material, part number, quantity, and sto k
room lo ation is inserted in the DEU. Ten olumns of
numeri data together with variable fields are transmitted
to the data pro essing system, updating the parts inventory.
Production Control
The ontrol of produ tion requires management to know
the status of work flow through the various steps of the
manufa turing pro ess. Data entry units installed at appro
priate ma hine lo ations and he kpoints an be used to
re ord dynami ally the time spent on ea h operation, work
pile-ups, quantity of parts flow, et . This data re orded on
the system is available to management for he king the
progress of an individual order through the shop, and work
ompleted for ea h step of the operation. It an also be
used to determine the need for additional apa ity at spe ifi
steps of the operation, or the need to shift work load to new
areas. Information on the status of shop loads an be used
in determining standard lead times for produ tion s heduling.
Introduction 7

Data Entry Units
The 2795 DEU and the 2796 DEU (designed for ruggedness
and simpli ity) are operator-oriented devi es for use in a
fa tory. The 2795 DEU is a small me hani al unit
(approximately 7 in hes by 10 in hes) ontaining a badge-
ard reader, two 10-position rotary swit hes, a phone-ja k,
an error indi ator/reset button, an entry flag, and an entry
request lever, all pa kaged in a single ompa t unit for
ben h or wall mounting (Figure 3). Wall mounting requires
| a ustomer-furnished shelf or bra ket.
The 2796 DEU ontains all the fun tions of the 2795
DEU plus two additional 10-position rotary swit hes, four
ro ker-thumbwheel swit hes, and a monitor key(Figure 4).
The DEU is onne ted to the AS by a ustomer-furnished
two-wire ommuni ations line, and ontrolled by the AS.
2795 DATA EN TRY UNIT
The 2795 DEU in ludes the following features.
Badge-Card Reader
A badge- ard reader lo ated on the top of the DEU reads
ten digits of numeri information pun hed as shown in
Figure 5.
The badge- ard reader an read ten olumns of numeri
data from either end of a pun hed ard or ten olumns of
numeri data from a 357/1030 style badge. Cards to be
read on a DEU should not have a 9-edge orner ut; a
9-edge orner ut may ause reading problems.
The DEU’s read 0 through 9 pun hes and blanks. If no
0 through 9 pun h is in a data olumn, the DEU reads that
olumn as a blank. If a data olumn is double pun hed, the
DEU reads the pun h losest to the 9-edge and ignores the
other pun hes in the olumn.
This numeri information is provided by the following
ombinations of pun hes in a standard 80- olumn ard, or
in the equivalent positions (Figure 5) of an identifi ation
badge.
Entry Flag Carcf/Badge Slot
Error Indicator/Reset Button
Phone Jack Entry
Request
Lever
Figure 3. IBM 2795 Data Entry Unit
Data Entry Units 9

Entry Flag Card or Badge Slot Error Indicator/
Reset Button
Monitor Key and
Phone Jack on
Left Side
Rotary Switches Rotary Switches
Figure 4. IBM 2796 Data Entry Unit
80 Column Card
Numeric Data
Col 71-80-Card fed 80
olumn end first, fa e
towards operator
Col 10-1-Card fed ol
umn 1 end first, fa e of
ard away from
operator
Identification Badge
Numeric Data
IBM 013 Badge Pun h
olumns 13 through 22
Registration Punches
Col 66—“9” and “11”
pun hes
Col 15—“9” and “11”
pun hes
Registration Punches
IBM 013 Badge Pun h
olumn 8—“9” and “11”
pun hes
2795 Data Entry
A 2795 data entry as assembled in the 2715 TCU onsists
of 12 digits of data plus transa tion-header information
(see Figure 6):
Digit 1—Type of DEU.
Digit 2—Setting of right-hand rotary swit h.
Note: Su h information as devi e address, area station
address, and left-hand rotary swit h setting are also
transmitted to the system ontroller. The system
ontroller onstru ts a transa tion header from this
information and prefixes it to the transa tion ontaining
the data entry.
Selection Switch
Note: Detailed information about the badges used for
the 2790 system is given in the Systems Referen e
Library Manual, 357/1030/2790 Badge Specifications,
GA21-9028.
A 10-position rotary swit h is lo ated on ea h side of the
DEU frame. These swit hes are apable of transmitting
numeri digits 0 through 9 to indi ate su h things as
status, names, or numbers. The transmitted digits are
10

It
Reading
Order
013 Badge
Punch
Columns
Registration Punches
Data
(Data Shown Reads 0123456789)
1
Corresponding
Card Rows
♦
Insert Column 80 End
of Card with Face
to Operator
Registration Punches
Data Punches (Data Shown Reads 1 234567899)
Registration Punches 15
Data Punches
(Data Shown Reads 9987654321)
Li
from Operator
• Figure 5. DEU Badge and 80-Column Card Punch Information
displayed through the indi ator openings in the front panel
of the DEU. The nomen lature designation of these swit hes
is optional ex ept for digits OX (X is any right-hand swit h
setting), whi h are reserved for learing and testing the oper
ation of the unit.
A holder is provided on the front over of the data entry
unit for insertion of sheets to indi ate the swit h nomen
lature or to provide operator instru tions.
Phone Jack
A telephone ja k on the left over is provided for the use of
a portable telephone handset for voi e ommuni ation via a
ustomer-provided voi e- ommuni ation network.
Error Indicator/Reset Button
In ase of an erroneous transmission, an error indi ator/reset
button on the top of the data entry unit snaps into view;
Data Entry Units 11

Transaction Header (8 Bytes)
123456 7 8
Transaction
Length
Transaction
List Number
*
Area
Station
Address
Device
Address
Tens
of
Hours
Units
of
Hours
Tens
of
Minutes
Units
of
Minutes
>
r --------------------
fJ
Binary Time-of-Day in EBCDIC
* Left-hand rotary switch setting is referenced to the user
transaction tables, and the transaction list number from
the table is placed in byte 2 of the header
Data Entry (12 Digits)
12345678910 11 12
ID Right- l l 1
Card or Badge Columns
Code Hand
Rotary 71 72 73 74 75 76 77 78 79 80
(0) Switch 13 14 15 16 17 18 19 20 21 22
(EBCDIC)
Figure 6. 2795 Data Entry as ssembled in the 2715 TCU
the entry request lever remains in the lat hed position; and
the ard or badge annot be removed from the reader. This
signals the operator that retransmission of the re ord is
required. The operator resets the terminal by pressing the
error indi ator/reset button. The indi ator/reset button is
also used to reset the terminal whenever a reset is required.
Entry Request Lever
Pushing down the entry request lever initiates a request to
the area station for servi e and furnishes the motive power
required to read the information entered by the operator.
The operator initiates the request for servi e by positioning
the lever in the lat hed position, whi h is indi ated by
“green” in the entry flag window.
The request lever annot be fully positioned if the ard or
badge is improperly registered. When the request lever is
lat hed in the request position, the ard or badge annot be
removed from the ma hine. When the omplete transa tion
has been re eived by the system ontroller, the request lever
is returned automati ally to its start position and the entry
flag is returned to its bla k position (ready for the next
entry).
2796 DATA EN TRY UNIT
The 2796 ontains all of the features of the 2795 plus three
additional features:
Rotary Switches. Two additional ten-position rotary
swit hes are provided, for a total of four swit hes.
Rocker-Thumbwhee Switches. Four ro ker-thumbwheel
swit hes lo ated on the front over permit manual entry of
four digits of numeri data.
Monitor Key. The monitor key lo ated on the left over
allows a key holder to add an approval to a given transa tion.
Approval is a omplished through the transmission of a
unique hara ter that is a tivated by using a key in a
three-position lo k swit h. The key must be returned to
the enter position to be removed. With the lo k turned
lo kwise, a 1 is transmitted; in the enter, a 2 is trans
mitted; and turned ounter lo kwise, a 3 is transmitted.
12

Transaction Header (8 Bytes)
12 3 45678
Transaction
Length
Transaction
List Number
*
Area
Station
Address
Device
Address
Tens
of
Hours
Units
of
Hours
Tens
of
Minutes
Units
of
Minutes
V
r mms J
Binary Time-of-Day (EBCDIC)
* Upper left-hand rotary switch references a transaction
from the user's transaction table The transaction list
number from the table is placed in byte 2 of the header
Data Entry (18 EBCDIC Digits)
Digit
Digit
12 3 4567 8 9
Monitor Upper
------------------ 1 i ------------------
Card or Badge Columns
Key Right 71 72 73 74 75 76 77
(1,2,or 3) Rotary
Switch 13 14 15 16 17 18 19
10 11 12 13 14 15 16 17 18
Lower Lower ■
Rocker Thumbwheel Switches
78 79 80 Left Right
20 21 22 Rotary
Switch Rotary
Switch 1234
Figure 7. 2796 Data Entry as ssembled in the 2715 TCU
2796 Data Entry
A 2796 data entry as assembled in the 2715 TCU onsists
of 18 digits of data plus transa tion-header information (see
Figure 7):
Digit 1—Monitor key setting and type of DEU.
Digit 2—Setting of upper right-hand rotary swit h.
Digits 3 through 12—Contents of ard or badge. Blanks
are transmitted for these positions if a ard or badge
is not entered as part of the data entry.
Digit 13—Setting of lower left-hand rotary swit h.
Digit 14—Setting of lower right-hand rotary swit h.
Digit 15 through 18-Setting of four ro ker-thumbwheel
swit hes.
Note: Su h information as devi e address, area station
address, and upper left-hand rotary swit h setting are
also transmitted to the system ontroller. The system
ontroller onstru ts a transa tion header from this
information and prefixes it to the transa tion ontaining
the data entry.
DATA EN TR Y UNIT TRANSACTION SELECTIO N
The ombination of the area station’s address, the data
entry unit’s address, and the setting of the left-hand (upper
left-hand for 2796) rotary swit h sele ts the proper trans
a tion list from the user’s transa tion-list table. The trans
a tion list provides the ontrols to pro ess the data entry.
All 2795’s assigned to a given AS must use the same
transa tion list for orresponding rotary-swit h settings
(transa tion ode). All 2796’s assigned to a given AS must
Data Entry Units 13

use the same transa tion list, different from the transa tion
list for 2795’s assigned to the AS^for orresponding
rotary-swit h settings (transa tion ode). Therefore, if
both 2795’s and 2796’s are atta hed to a given area station,
the transa tion number sele ted on the 2795’s referen es
one transa tion list and is subje t to ertain ontrol steps
and routing, while the orresponding transa tion number
sele ted on the 2796’s referen es another transa tion list
and is subje t to different ontrol steps and routing.
Transaction Expansion
The DEU transa tion sele tion may be expanded beyond
the nine transa tion odes on the left-hand rotary swit h by
using “transa tion expansion.” Transa tion expansion allows
the right-hand (upper right-hand for 2796) rotary swit h to
supply a se ond digit to the transa tion ode, allowing a
maximum sele tion of 81 different transa tions.
DEU transa tions sele ted by transa tion expansion
must be single data entry transa tions.
Transa tion expansion is a prerequisite when using the
routing apability provided by the Expanded Capability
feature.
Transa tion expansion is a tivated when the programmer
defines the transa tion odes in the transa tion group
(TGROUP) ma ro. See IBM System/360 Operating System,
Basic Te ecommunications Access Method, GC30-2004; or
IBM System/360 Disk Operating System, Basic Te ecommu
nications Access Method, GC30-5001.
14

Area Stations
The area station is designed to serve as a primary ommuni
ation terminal for a work area or fa tory floor. The basi
fun tions of the AS are to: (1) a ept data from the various
input devi es and transmit it to the transmission ontrol
unit, and (2) a ept data from the TCU and forward it to
output devi es. Two types of area stations, the IBM 2791
and IBM 2793, are available:
IBM2791 IBM2793
(Mode 1 and Mode 2)
1000-foot able trans
mission apability
(#22 AWG twisted
pair)*
Card reader—80- olumn
Badge reader—10- olumn
9 transa tion sele tion keys
12-key manual entry
6 digits of display
Time-of-day display (when
manual-entry digits are not
being displayed)
Operator guidan e
Monitor key
1000-foot able trans
mission apability
(#22 AWG twisted
pair)*
2795/2796 Atta hment
basi (atta hment
for first 8 DEU’s)
Features (Model 1 only :
IBM 1035 Badge Reader
atta hment
IBM 1053 Printer atta h
ment
Digital devi e read-in (OEM)
2795/2796 Atta hment—
I basi (atta hment for
first 8 DEU’s)
2795/2796 Atta hment-
additional (3 atta h-
I ments; 8 DEU’s per
I atta hment)
2791 A REA STATION
Features
2795/2796 Atta hment-
additional (3 maximum)
IBM 1053 Printer atta h
ment
The 2791 Area Station omes in two models. The 2791
Model 1 is a ombination of an input station and a ontrolle]
for external devi es. The 2791 Model 2 is an input station
only; it does not ontrol external devi es. The 2791 is
*Refer to the Systems Reference Library manual, IBM 2790 Data
Communication Sy tem In tallation Manual-Phy ical Planning,
G 27-3017, for maximum length of other wire sizes.
either ben h- or shelf-mounted. As many as 100 AS’s may
be onne ted to a transmission ontrol unit by means of a
high-speed (about 500,000 bits per se ond) two-wire
transmission line. The area stations are onne ted serially,
starting and terminating at the TCU in a serial loop onfigu
ration.
Area Station Nomenclature
Commonly used words with a spe ifi meaning for the 2790
system are:
Data Entry. A single blo k of data entered by an operator
at the area station using a single data-entry devi e. For the
ard reader, a data entry onsists of a ard; for the badge
reader, a badge; and for the numeri keyboard, one to six
digits.
The maximum-length data entry is 81 hara ters—
onsisting of 80 olumns from the ard reader, plus one
EBCDIC (Extended Binary Coded De imal Inter hange Code)
hara ter used to re ord the setting of the monitor key. This
information hara ter is in luded with every data entry from
resident ard reader, badge reader, manual entry devi e, and
Digital Devi e Read-In feature. It is not in luded with data
entries from 1035 Badge Readers.
Note: Su h information as devi e address, area station
address, and transa tion key setting are also transmitted
to the system ontroller. The system ontroller on
stru ts a transa tion header from this information and
prefixes it to the transa tion ontaining the data entry.
Mu tip e-Input Transaction Steps. The Area Station List
(ASLIST) ma ro instru tion an designate a transa tion
step to re eive multiple data entries. For a transa tion step
designated as a multiple-data-entry step, the transa tion step
and guidan e light remain the same for the multiple data
entries. The operator ends the transa tion step by pressing
the Next Guidan e key. (Any one transa tion is limited to
a maximum of 247 bytes of data.)
All but the first data entry of a transa tion may be
spe ified as multiple input. If multiple input is spe ified
for the first data entry, an invalid user table assembly o urs.
Transaction. A user-defined series of data entries whi h will
be olle ted by the system ontroller and may be routed to
the pro essor and/or other output devi es. A transa tion is
entered by the Area Station operator under guidan e from
the system ontroller.
rea Stations 15

Figure 8. Segmentation
Transaction Code Character. An eight-bit hexade imal data
byte transmitted from the area station to the system on
troller indi ating whi h transa tion key has been depressed
by the operator, and other ontrol onditions.
Transaction Expansion. The apability of sele ting one of
81 possible transa tions using the normal transa tion
sele tion swit hes (1-9) followed by an expansion digit
(1-9). The transa tion expansion digit an be entered from
the ard reader, the resident badge reader, the digital read-in
devi e, or the manual keyboard; however, only one devi e
type an be designated for ea h transa tion sele tion
swit h.
For the ard reader, resident badge reader, and the
digital read-in devi e, the expansion digit is the first digit
(monitor key ex luded) transmitted within the first data
entry of a transa tion. For the manual keyboard, the
transa tion expansion digit is also the first digit trans
mitted; however, be ause the first digit transmitted from
the manual keyboard is the one that appears in the left
most visual display position, manual keying must ontinue
until the transa tion expansion digit has rea hed that
position. This an be a omplished by keying the digit
six times or by keying the digit and then using the remain
ing five positions for data.
Area station transa tions sele ted by transa tion expan
sion may be multiple-input data entries.
Note: Digit zero is an invalid transa tion expansion
digit.
Transa tion expansion is a prerequisite for message
routing. Transa tion expansion is a tivated when the pro
grammer defines the transa tion odes in the transa tion
group (TGROUP) ma ro. See IBM System/360 Operating
System, Basic Te ecommunications Access Method,
GC30-2004; or IBM System/360 Disk Operating System,
Basic Te ecommunications Access Method, GC30-5001.
Guidance Pane A 36-position lighted display matrix
(four olumns, nine rows), of whi h 31 positions are
available to the ustomer to give spe ifi instru tions to the
area station operator. The 32nd position is reserved for the
Sele t Transa tion display. Positions 33 through 36 are
operational indi ators.
Guidance Character. An eight-bit data byte transmitted
from the system ontroller to the area station to indi ate
the operator-guidan e light to be lighted, the devi e to be
read, and the state of the In-Pro ess light.
Transmission Capability
The 2791 and 2793 Area Stations are onne ted serially by
a two-wire able. The area stations are designed so that if
one area station is turned off or otherwise loses power,
operation of the loop is not affe ted. The adja ent area
station on the loop supplies power, via the loop onne tion,
to a portion of the ina tive area station, thus maintaining
loop operation. The transmission-line rate is about 500,000
bits per se ond.
16

Transaction
Nomenclature Badge Reader
Operator Guidance
Lights
Manual Entry
Keyboard
Card Reader
Control Keys
Figure 9. IBM 2791 rea Station
The transmission line is divided into four segment. This
transmission-line segmentation (Figure 8) permits a ess to
area stations on other segments even though one or more
segments be ome inoperable.
The 2790 transmission line provides 13 time-multiplexed
hannels of data, all operating on urrently. Eight of these
hannels operate at an effe tive data rate of approximately
100 hara ters per se ond per hannel; the other five oper
ate at approximately 20 hara ters per se ond per hannel.
The lower-speed hannels are used to send data to IBM 1053
Printers. The higher-speed hannels are used for all 2790
system input devi es and for broad asting time of day to the
2791 visual display.
De ete-B anks Option
The delete-blanks option is a ustomer option that is wired
by the ustomer engineer when the area station is installed.
When the option is wired ON, blank olumns from the AS
badge reader, 1035 Badge Reader, or Digital Devi e Read-In
feature are deleted from the data transmitted to the system
ontroller. When the option is wired OFF, the hara ter
X‘40’ is sent to the system ontroller for ea h blank olumn.
Card Reader
The ard reader is lo ated on the right front (Figure 9) of
the area station and a epts alphameri and spe ial hara 
ters (Figure 10), translating them to Extended Binary Coded
De imal Inter hange Code (EBCDIC) for transmission to
the system ontroller. Blank olumns are not transmitted to
the system ontroller. End of ard (EOC) is sensed by either
reading an EOC hara ter or by sensing the end of the ard.
Card-reading rate is approximately 60 hara ters per se ond.
Cards are inserted in the ard re eiver, fa e up, olumn-one
end first. An upper left orner ut is required to ensure that
the ard has been entered properly.
Badge Reader
The badge reader in the area station is lo ated in the upper
front of the station (Figure 9). The badge reader reads ten
olumns of numeri information. Information from the
badge moves onto the ommuni ations network from high
order to low order (013 Badge Pun h olumn 13 to
olumn 22). Blank olumns in the badge are transmitted
to the system ontroller unless the delete-blanks option
is a tivated.
rea Stations 17

Character Card Punch EBCDIC
0123 4567 Hexadecimal
A12-1 1100 0001 Cl
B12-2 1100 0010 C2
C12-3 1100 0011 C3
D12-4 1100 0100 C4
E12-5 1100 0101 C5
F12-6 1100 0110 C6
G 12-7 1100 0111 C7
H12-8 1100 1000 C 8
1 12-9 1100 1001 C9
J 11-1 1101 0001 D1
K11-2 1101 001 0 D2
L11-3 1101 0011 D3
M11-4 1101 0100 D4
N11-5 1101 0101 D5
O 11-6 1101 0110 D6
P 11-7 1101 0111 D7
Q11 -8 1101 1000 D8
R11-9 1101 1001 D9
S0 -2 1110 0010 E2
T0-3 1110 0011 E3
U0-4 1110 0100 E4
V0-5 1110 0101 E5
W0-6 1110 0110 E6
X0-7 1110 0111 E7
Y0 -8 1110 1000 E8
Z0-9 1110 1001 E9
00m i oooo F0
11m i o oo i FI
22n n o o io F2
33n n o o n F3
441111 0 100 F4
551111 0101 F5
661111 0110 F6
771111 0111 F7
881111 1000 F8
991111 1001 F9
a12-0-1 1000 0001 81
b1 2 -0 - 2 1000 0010 82
c12-0-3 1000 0011 83
d12-0-4 1000 0100 84
e12-0-5 1000 0101 85
f1 2 -0 - 6 1000 0110 8 6
912-0-7 1000 0111 87
h1 2 -0 -8 1000 1000 88
i12-0-9 1000 1001 89
Character Card Punch EBCDIC 0123 4567 Hexadecimal
i12-11-1 1001 0001 91
k 12-11-2 1001 0010 92
112-11-3 1001 0011 93
m 12-11-4 1001 0100 94
n 12-11-5 1001 0101 95
o 12-11-6 1001 0110 96
P12-11-7 1001 0111 97
q12-11-8 1001 1000 98
r12-11-9 1001 1001 99
s11-0-2 1010 0010 A2
t11-0-3 1010 0011 A3
u11-0-4 1010 0100 A4
V11-0-5 1010 0101 A5
w11-0-6 1010 0110 A6
X11-0-7 1010 0111 A7
y11-0-8 1010 1000 A8
z 11-0-9 1010 1001 A9
912-2-8 0100 1010 4A
12-3-8 0100 1011 4B
<12-5-8 0100 1101 4D
[phone]E
112-7-8 0100 1111 4F
&12 0101 0000 50
! 11-2-8 0101 1010 5A
$11-3-8 0101 1011 5B
*11-4-8 0101 1100 5C
)11-5-8 0101 1101 5D
}11-6-8 0101 1110 5E
11-7-8 0101 n n 5F
-11 0110 0000 60
/0-1 0110 0001 61
/0-3-6 0110 1011 6B
%0-4-8 0110 1100 6C
—0-5-6 0110 1101 6D
>0-6-8 0110 1110 6E
? 0-7-8 0110 1111 6F
2-8 0111 1010 7A
#3-8 0111 1011 7B
@4-6 0111 1100 7C
■5-8 0111 1101 7D
=6-6 0111 1110 7E
"7-8 0111 1111 7F
* EOC 12-4-8 —
* Blank No Punch —
* Not transmitted
Figure 10. cceptable rea Station Character Set and Card Code
Badges are manually inserted (horizontally, fa e up,
guide-hole first). Badges that are inserted improperly are
not a epted. Properly inserted badges are retained at the
badge-reading station until ompletion of a orre t trans
mission. Data-transfer rate of the badge reader is approxi
mately 100 hara ters per se ond.
Transaction Selection Switches
The transa tion sele tion swit hes are ten pushbutton
swit hes lo ated on the left front of the area station
(Figure 9). Sele ting any of the first nine swit hes lo ks
the swit hes until the last swit h (Release) is pressed.
Sele tion of any one of the first nine swit hes by the
operator generates an eight-bit hara ter that identifies the
type of transa tion hosen. The system ontroller an
assign (at the user’s option) different meanings to ea h
swit h based on the area station address.
Control Keys
The Area Station ontains four spe ial purpose ontrol
keys: Enter, Clear, Next Guidan e, and Monitor.
18

Enter Key (ENTR
The Enter key enters the data that was keyed via the
manual keyboard into the system as a data entry.
Clear Key
The Clear key lears an una epted data entry from the
area station, extinguishes the Error lamp, releases the
media ( ard or badge), and lears the display. The operator
presses the Clear key to lear display before entering data
through the keyboard.
Next Guidance Key
The Next Guidan e key signals that the last data entry
of a multiple data entry transa tion step (“M” transa tion
step) has been entered and alls for the next guidan e step.
This key is also used to relight the original guidan e light
on a data entry step after an error light has been turned on,
ex ept on the first data entry of a multiple step transa tion.
Monitor Key
The Monitor key is lo ated on the lower left over. This
key is a key-lo k swit h that allows the key holder to add
an approval to a given transa tion. Key OFF sends a 0 as
the first digit of the data entry; key ON sends a 1 as the
first digit of the data entry.
TRANSACTION
SELECTION
SWITCHES
CUSTOMER
TRANSACTION
NOMENCLATURE
OPERATOR
GUIDANCE
NOMENCLATURE
1ATTENDANCE
2 WORKSHOP BADGE
3MAN
NUMBER
4CARD
5
6
7
8SELECT
TRANSACTION
9ON LINE REPEAT/CLEAR IN PROCESS CARD IN
CARD READER
RLS OPERATIONAL INDICATORS
0 e 3D3 n
VISUAL DISPLAY
Manual Entry F igure 11. Operator Panel
The 12-key numeri keyboard lo ated at the lower front
provides for the entry of de imal numeri s 0 through 9,
-, and =. As ea h key is pressed, the number or spe ial
hara ter is displayed to the operator for verifi ation. Up
to six positions are displayed for any one data entry. After
verifi ation, an Enter key is pressed to transmit the data to
the 2715 TCU at approximately 100 hara ters per se ond.
Additional data entries from the keyboard may be hained
into one transa tion under 2715 user-table ontrol (trans
a tion list steps).
Visual Display
A six-position visual readout is lo ated on the lower front
over. As many as six digits of numeri data an be verified
in the visual display before transmission. Valid hara ters
are 0 through 9, blank, -, and =. The time of day is displayed
when manual entry is not in use. The time-of-day display is
valid if the On Line light is on. The time may not have been
updated if the On Line light is off.
Operator Guidance Panel
The operator guidan e panel (Figure 11) has three se tions-
transa tion sele tion area; operator guidan e nomen lature;
and operational indi ators.
Transaction Selection Area
Adja ent to ea h transa tion key is an area in whi h the
ustomer may provide nomen lature in language appropriate
to his industry or appli ation. This area des ribes a parti ular
transa tion that is handled if the adja ent button is pushed.
User options at the system ontroller an vary key assign
ments between 279 Fs.
Operator Guidance Nomenclature
This se tion of the operator guidan e panel onsists of a
4 by 8 light matrix in whi h one re tangle of the 32 is
illuminated as a result of de oding the low-order five bits of
the guidan e hara ter. The light panel des ribes in the
ustomer’s own words a tions to be taken by the operator—
that is, the type of badge, ard, or other signifi ant informa
tion relative to the expe ted data entry. Of the 32 guidan e
hara ters, 31 are available to the ustomer. The 32nd one
is dedi ated to “sele t transa tion”, whi h notifies the op
erator that a new transa tion may be sele ted. (The Release
transa tion pushbutton must be pressed before a new trans
a tion an be sele ted.)
The programmer defines whi h guidan e lights are turned
on for a transa tion when he defines the transa tion list
| (TRLIST) ma ro. See Systems Referen e Library manuals,
rea Stations 19

IBM System/360 Operating System, Basic Te ecommunica
tions Access Method, GC30-2004; or IBM System/360 Disk
Operating System, Basic Te ecommunications Access
Method, GC30-5001.
Operator Guidance Pane Mask. The ustomer makes the
guidan e panel mask (overlay) to suit his own needs. The
mask an be made by photographi pro esses or by standard
offi e opying equipment using heavy-duty proje tion trans
paren y paper. Figure 12 shows various lettering effe ts
that ould be used in a guidan e panel mask.
Full-size guidan e panel templates are in luded at the
end of this manual to aid in laying out the masks. The num
bers within the boxes identify the lights as they are refer
en ed by the transa tion list ma ros. The nomen lature for
the Release transa tion swit h, the Sele t Transa tion light,
and the operational indi ators should be in luded on ea h
guidan e panel mask.
Operational Indicators
The third se tion of the guidan e panel onsists of the
operational indi ators: On Line, Repeat/Clear, In Pro ess,
and Card In Card Reader.
On Line Indicator. Indi ates that the area station is opera
tional. The area station is operational as a result of:
1. Power on
2. Area station syn hronized with system ontroller
and unit not bypassed
3. System ontroller available to re eive data.
Note: If the 2715 system ontroller is in a “stop 2790
input” status, but available for write operations to the
loop terminals, a dash symbol is displayed in the visual
display. The dash is displayed in the first position to the
left of the high order time digit. The dash alerts the
operator that the 2715 is not available to re eive data,
but an send data to 1053 Printers on the loop.
4. CE Mode swit h on CE panel in operator position
5. CE Transa tion swit h off
6. Area station not in diagnosti mode.
In Process Indicator, illuminated following the 2715’s
a eptan e of the first data entry of a multiple-entry trans
a tion. The indi ator remains on until the entire transa tion
is omplete.
Card In Card Reader Indicator. Notifies the operator that
a ard has been inserted into the ard reader. The ard will
not return until either the data has been a epted or the
Clear key has been pressed.
Area Station Addresses
The area stations are assigned addresses when they are in
stalled. The area station (AS) addresses are (80 hex)
through (E3 hex). The AS sends its address with ea h data
entry. Ea h devi e tied to an AS has a preassigned devi e
address as follows:
Badge Reader . . .
Card Reader . . .
Keyboard ....
Digital Devi e Read-In
1035 Badge Reader .
1053 Printer . . .
Data Entry Units . .
2791 Data Entry
The area station data entry varies a ording to whi h devi e
entered the data. Figure 13 shows the data entry for ea h
devi e.
Adapters
2795/2796 A ttachments
Two DEU atta hment features, 2795/2796 Atta hment
Basi and 2795/2796 Atta hment Additional, provide for
atta hing up to 32 data entry units. The 2795/2796
Atta hment Basi , whi h provides for atta hing the first
eight DEU’s, is an optional feature for the 2791 Model 1
and a standard feature for the 2793. The 2795/2796
Atta hment Additional, whi h provides for atta hing addi
tional DEU’s in up to three groups of eight, is an optional
feature of both the 2791 Model 1 and the 2793.
The DEU atta hment (adapter) provides the s anning
to sele t any one of the 32 possible data entry units re
quiring servi e. The adapter servi es the devi es on a
blo king basis—that is, one devi e at a time until the mes
sage is ompleted. Upon ompletion of a message from a
DEU, the s an ontinues until another devi e requires
servi e. The operation is then repeated. The adapter de
odes and generates the input-devi e address, de odes the
ontrol ode, and generates the proper ontrol-response
hara ters. The DEU atta hment a epts data from the
DEU and translates the data to the proper hexade imal
hara ter for transmission to the 2715. The valid hara ter
set is limited to de imal numeri s 0 through 9 and blank.
1053 Printer Attachment (Optional on 2791 Model 1 and
2793
The 1053 Printer Atta hment (adapter) allows the onne tion
of one 1053 Model 1 to ea h area station. The adapter de
odes and generates the devi e address, de odes and a ts
upon the ontrol ode, generates the proper response har
a ters, and a epts EBCDIC hara ters from the transmission
line and translates them to the tilt/rotate ode for the 1053
Printer operation. This adapter will translate 44 EBCDIC
upper ase hara ters (see Figure 14). The adapter also
. . . . (80 hex)
. . . . (84 hex)
. . . . (88 hex)
. . . . (8C hex)
. . . . (81-83 hex)
. . . . (40 hex)
. . . . (C0-DF hex)
20