IBM 2265 User manual
Systems
Reference Library
IBM
System/36D
Component Description
IBM
2265
Display Station
Modell
IBM
2845
Display Control
This manual describes the functional and operating characteristics
of
the
I
IBM
2265 Display Station Model 1 and the
IBM
2845 Display Control. The
two units combine to form a display system
that
provides visual access
to
I
data stored in an
IBM
System/360. The
IBM
2265 Display Station Model 2,
which can be attached only
to
an
IBM
2772 Multi-Purpose Control Unit,
is
described in System Components: IBM 2770 Data Communications
System, Form GA27-3013.
File No. S360-09
Form
GA27-2731-2
Preface
This SRL publication assumes the reader has a knowledge
of
System/360 principles
of
operation. Therefore,
dis-
cussions
of
such System/360 considerations
as
instruction
and command structures, Channel Status Word and Pro-
gram Status Word locations and usage, varieties and pri-
orities
of
interruptions, and generalized capabilities such
as
I/O channel status and sense byte usage, command and
data chaining, length suppression, etc., have been kept
to
a minimum. This publication does not differentiate be-
tween the various models
of
System/360; i.e., main storage
capacities, subchannel allocations, sharing and nonsharing
of
I/O channel and processor circuitry, and
so
forth. The
reader
is
directed
to
the authoritative source for each
model
of
System/360,
System/360
Functional Character-
istics (by model). Other
IBM
publications that will be
of
use to the reader are:
Third Edition (January, 1970)
I
IBM
System/360
Principles
of
Operation, Form
GA22-6821
IBM 2701 Data
Adapter
Unit -ComponentDescription,
Form GA22-6864
IBM
System/360
Bibliography, Form GA22-6822
IBMMultiplexers and Communications Terminals
Installation Manual- PhysicalPlanning, Form
GA27-3006
Note: In this manual, "I/O (input/output) channel" refers
to a multiplexer channel. This device provides the data
path and controls between the central processor and the
2701 Data Adapter Unit. "Communications channel"
refers
to
the communications medium (telephone lines,
telegraph, microwave, etc.) used to transmit data, via
appropriate data sets, between the 2701 and the 2265-1/
2845 display system.
This
is
a major revision of, and obsoletes, Form A27-2731-1 and Technical Newsletter N27-2948.
The significant changes in this edition include the following:
1.
The title has been changed to reflect that this publication describes the 2265
Modell;
a
reference
to
the
publication
that
describes
the
2265 Model 2 has been added
to
the abstract.
2.
Line Addressing Feature 4802 has been removed and Line Addressing Feature 4801 has
been revised.
3.
Installation planning data has been replaced with a reference to the publication
that
contains
this data.
4.
Display station keyboard indicator and pushbutton names have been corrected.
Changes to
text
and tables are indicated
by
a vertical line
to
the left
of
the change; changed
illustrations are denoted by
the
symbol.
to the left
of
the caption.
Changes are periodically made
to
the specifications herein; before using this publication
in connection with
the
operation
of
IBM
systems, refer
to
the latest System/360 SRL
Newsletter, Form GN20-0360, for the editions
that
are applicable.
Text for this manual has been prepared with the
IBM
SELECTRIC @Composer.
A form is provided
at
the
back
of
this publication for reader's comments.
If
the form
has been removed, comments may be
addJ:essed
to:
IBM
Systems Development Division,
Product Publications, Dept. 520, Neighborhood Road, Bldg. 960-1, Kingston, N.Y., 12401.
©Copyright International Business Machines Corporation, 1967, 1968, 1970
Contents
Introduction 7 General Poll . 33
Highlights 7 Read Addressed Full
DS
Buffer
33
General Description 7 Write Addressed
DS
36
Programming Support 8 Erase/Write Addressed
DS
.
37
Features . 8 Write Printer .
38
Specify Features 8 Printer Request Condition . 40
Data Set Adapters 8 Simultaneous Keyboard and Printer Operations 40
Display Format Features 9 Write
DS
Li~
Address .
41
World Trade Language Features 9 Summary
of
Sequences and Responses 42
Voltage Features 9 2845 Display Control Sequences and Responses 42
Special
Features.
9 Start
of
Text (STX) 42
Alphameric Keyboard Feature (4766) 9 End
of
Text (ETX) . 42
1053 (Printer) Adapter Features 9 Cancel
(CAi,O
42
Line Addressing Feature (4801) 9 Positive Acknowledgment (ACK) . 43
Destructive Cursor Feature (3301) 10 Negative Acknowledgment (NAK) 43
Tab Feature (7801) . 10 End
of
Transmission (EOT) 43
System Configuration 10
No
Response 43
Data
Sets.
10 I/O Channel Sequence and Responses 44
U.S. (Domestic) Operation 10 Start
of
Text (STX) 44
World Trade
Operation.
10 End
of
Text (ETX) . 44
Typical Display System Operation 10 Positive Acknowledgment (ACK) 44
Operation with 1053 Printer
12
Negative Acknowledgment (NAK) 44
2265 Display Station Operator Controls and Indicators 12 Start
of
Heading (SOH) 44
Display Station Keyboard
13
End
of
Transmission (EOT) 44
Character Keys
13
Start
of
Text/End
of
Transmission (STX/EOT) 44
Control Keys
13
Line Feed (LF) 44
Special
Symbols.
13 Error Recovery Procedures
45
Cursor-General Description 13
NAK
Response
to
Addressing Sequence
45
Nondestructive Cursor Symbol (Standard)
13
NAK
Response
to
Text
45
Destructive Cursor Symbol (Feature)
16
EOT Response
to
Addressing Sequence
45
End
of
Message
(EOM) Symbol
16
EOT Response
to
Text .
45
Start
of
Message
(SOM)
Symbol 19
CAN
Response
45
New
Line (NL) Symbol
19
No
Response to Addressing Sequence or Text
45
Check Symbol
19
I/O Channel Commands, CCW's, and Ending Status
Control Key Functions .
20
and Sense Bytes 46
2265 Display Station Keyboard Operations 20
Manual Input 20 Installation Planning Data 49
Use
of
New Line (NL) Symbol
22
Correction
of
Errors from 2265 Keyboard 22 Appendix A. Feature Charts 50
2265-to-Printer Operation . 22
Tab Feature
Operation.
23
Display System Test Procedure (Wrap Test) .
23
Appendix B. World Trade Language Features 52
Introduction . 52
Principles
of
Operation
25
2265/2845 Character Sets . 52
USASCII Code Set
25
IBM
1053 Model 4 Printer Print Elements 53
Transmission Code Byte Structure
25
2265/2845 Labels, Indicators, and Switches 53
Block Diagram Analysis
25
IBM
2701 Data Adapter Unit .
25
Appendix C.
USASCII-8
to
Hexadecimal
Data
Sets.
25
Code Conversion 54
US
ASCII Communication Control Characters
27
2845 Display Control Modes
of
Operation
27
Control Mode
27
Appendix
D.
Timing Considerations 55
Text Mode
27
Interface Timing 55
Parity Checking
28
27tH
Line Timeout .
55
Addressing Sequence
28
Command Execution Timings .
55
2845 Commands and Command Operation
29
Specific Poll
to
2265 Display Station 30 Index 57
Specific Poll to 1053 Printer 30
Illustrations
Frontispiece
IBM
2265 Display Station (Design Model) 8 General Poll, Sequence/Response Diagram 34
IBM
2845 Display Control (Design Model) 9 Read Addressed Full
DS
Buffer, Sequence/
1 Typical Connection
of
an
IBM
2845 Display Response Diagram.
35
Control
to
a Remote Central Processor 10 Write Addressed DS, Sequence/Response
Showing Application in a Multidrop Com- Diagram
37
munications Network .
11
11
Erase/Write Addressed DS, Sequence/
2 2845 Display Station Keyboard
13
Response Diagram.
38
3 Example Display Showing SOM, NL, Check 12 Write Printer, Sequence/Response Diagram
39
Symbols, and Nondestructive Cursor (15 x 64 13 Write
DS
Line Address, Sequence/Response
Display Format)
21
Diagram
41
4 USASCII
-8
Code Set 26 14 2265 Feature Chart . 50
5 Ten-Bit
Format
of
Transmitted USASCII
15
2845 Feature Chart . 51
Characters
27
16 2265 United Kingdom Keyboard 52
6 Specific Poll
to
Display Station Sequence/ 17 2265 French Keyboard 52
Response
Diagram.
31
18 2265 German Keyboard 53
7 Specific Poll
to
Printer, Sequence/Response 19 Command Execution Timings .
56
Diagram 32
Tables
1 Functions
of
2265 Display Station Keys 8 I/O Channel Read Command Ending Status
(Nondestructive Cursor) 14 and Sense Bytes 48
2 Functions
of
2265 Display Station Keys 9 2265/2845 and 1053 Language Feature
(Destructive Cursor)
17
Character Differences . 53
3 Display Control Address Assignments 29 10 United Kingdom, French, and German
4 Remote Device Address Assignments . 29 Labels, Indicators, and Switches . 53
5 2265/2845
Commands.
29
11
USASCII-8 to Hexadecimal Code Con-
6 Display Line Addresses . 42 version Chart
54
7 Sample
CCW
Formats for Information Inter-
change Between 2845 and I/O
Channel.
47
IBM
2265 Display Station (Design Model)
IBM
2845 Display Control (Design Model)
The
IBM
2845 Display Control, coupled with an
IBM
12265 Display Station
Modell,
forms a display system that
provides rapid visual access (via communications facilities)
to
data stored in a remotely located System/360 Models
25
Ithrough
85
or 195. The 2265 Display Station
Modell
(hereafter called the 2265)
is
a high-speed display terminal
that operates under control
of
the compact 2845 Display
Control. The display system
is
designed
to
meet the
requirements
of
customers whose facilities are widespread
and who need a small number
of
display terminals at
each facility capable
of
two-way communications with a
centrally located computer.
For example, consider a company whose central
processing unit
is
located at company headquarters
in
Chicago and whose branch offices and warehouses are
scattered throughout the country. Each outlying loca-
tion may be equipped with a number
of
2265/2845 dis-
play systems commensurate with its business volume.
By
means
of
communications facilities (such
as
phone
lines, data channels, etc.), each display system can store
data in, and receive visual information from, the central
processor.
This system satisfies the needs
of
customers who
re-
quire relatively few displays or who desire
to
supplement
an existing display system.
It
is
ideally suited
to
applica-
tions that require immediate data acquisition capabilities
at
relatively low cost.
An
inquiry concerning an account, a transaction, a
production schedule, etc., can be entered quickly and easily
in the remote computer from the 2265 keyboard. After
being processed by the computer, the desired information
is
displayed
on
the 2265 screen in the form
of
visual data.
Here, the display information can be analyzed, modified if
necessary, and, when desired, returned to the computer
for further processing and storage.
The 2845 may also be equipped with a special feature
to
permit attachment
of
an
IBM
1053 Model 4 Printer.
The Printer may be used
to
produce a paper copy
of
data
sent from the central processor or
of
data displayed on
the 2265 screen.
HIGHLIGHTS
• Character presentation uses an advanced stroke-generation
technique
that
results in characters
of
unusual clarity
and smoothness.
• 2265 CRT uses Type P39 phosphor
to
produce a green-
tinted display.
Introduction
• Each 2265 has a capacity
of
960 characters, with an
optional display format
of
either
15
rows
of
64 charac-
ters or 12 rows
of
80 characters.
• Transmission speeds
of
either 1200 bps or 2400 bps.
• Optional attachment
of
an
IBM
1053 Model 4 Printer.
• Optional attachment
of
an alphameric keyboard which
may be located up
to
5 feet from the Display Station.
• Rapid cursor (character position marker) movement
is
provided in forward and backward directions.
•
By
operator control, the display screen can be erased
either a line at a time, a section at a time, or completely.
• Optional Tab feature.
• A nondestructive cursor is standard; a destructive
cursor
is
optional.
• Line addressing
to
permit selective writing
is
also
available.
• For World Trade customers, a 50-Hz power option is
available. Also available are keyboards for the following
languages:
United Kingdom English
French
German
GENERAL DESCRIPTION
The 2265/2845 display system consists
of
two separate
1units: the
IBM
2265 Display Station
Modell
and the
IBM
2845 Display Control. The 2845
is
a free-standing unit
which contains the storage and control logic necessary
to
interface with a 2265 and appropria.te communications
facilities. The unit provides for additional features such
as
the printer adapter and the 1200-bps or 2400-bps data set
adapters described below.
The 2845
is
designed for remote attachment
to
a
System/360-type I/O channel through an IBM2701 Data
Adapter Unit equipped with
IBM
Terminal Adapter Type
III. Program compatibility permits multidropping with the
IBM
2848 Display Control. Up
to
sixteen 2845's may be
attached
to
the same communications channel. The
relatively small size
of
each unit enhances the display
system's desirability in installations wherein limited space
is
a factor.
Introduction 7
The 2265 Display Station contains the 14-inch
cathode-ray tube (CRT) upon whose screen a maximum
of
960 alphameric characters can be displayed. The 2265
is
equipped with an alphameric keyboard to make it a
complete input/output (I/O) device. The keyboard
is
connected
to
the display station by a cable which permits
the keyboard
to
be positioned up to 5 feet away from the
display. Display station cover design
is
such that when the
display and keyboard are correctly positioned together
they appear
as
a single unit.
The face
of
the CRT (i.e., the display screen)
is
coated
internally with Type P39 phosphor
to
produce characters
having a green tint. By redrawing the displayed characters
I
approximately 50 times a second (technically, a refresh rate
of
approximately 50 Hz), a nonflickering image
is
formed.
Through use
of
an
advanced character-generation
technique, the electron beam
is
moved in a series
of
short
strokes to form each character.
By
deflecting the beam
(up to a maximum
of
40 times), blanking and unblanking
it
as
necessary, a character
is
drawn on the display screen.
The strokes required
to
compose each character are
predefined and are automatically generated via digital-to-
analog conversion by a character generator. Therefore,
character generation need not be considered when pro-
gramming the display system. The character generator
responds to the characters received from the 2845 and
produces the corresponding analog signals. These signals
are applied
to
a deflection yoke surrounding the neck
of
the CRT to control the luminous trace
of
the electron
beam. By blending together the strokes
that
compose each
character, characters
of
unusual smoothness are formed
on the display screen.
An antireflective display screen
is
used on the 2265
Dis-
play Station
to
minimize reflections from ambient light
sources and reflective objects. A manually operated bright-
ness control ensures comfortable viewing in installations·
'with
room light ambients
of
up
to
75
footcandles.
PROGRAMMING SUPPORT
2701 Teleprocessing (TP) applications
are
made easier and
more efficient by the use
of
the IBM-supplied programming-
support packages. The primary support packages consist
of
a pair
of
data-management access methods designed
specifically for the TP environments. These access methods
satisfy the programming requirements for a large portion
of
commonly used TP applications, including the 2848 and
2260. They operate under either a full Operating System
(OS) or the smaller Disk Operation System (DOS). The
2265/2845 can operate under these two programming
packages.
One
of
the access methods,
BT
AM
(Basic Telecom-
munication Access Method), provides the programmer
with simple, efficient access to the communication environ·
ment
so
that he can program the terminal in a manner
8
consistent with
that
used for conventional sequential-type
I/O devices.
BT
AM
controls data transmission; however,
it does not provide for elaborate message-queuing capability
or for actual processing
of
the message itself.
The second access method,
QTAM
(Queued Telecom-
munication Access Method), provides all the above-
mentioned capabilities
of
BT
AM.
In addition,
it
incor-
porates facilities for queuing messages on direct-access
storage devices (e.g., disk, drum, etc.).
QTAM
also pro-
vides capabilities for data-collection and message-switching
applications and may be used intact
both
for these functions
and for a large range
of
other
TP
uses. Like
BT
AM,
QT
AM
insulates the programmer from most
of
the programming
details
of
the 2701 and the attached terminal equipment.
The appropriate SRL publications should be consulted
for detailed information concerning the use
of
these access
methods.
In some cases, primarily because
of
special system con-
figurations or requirements, TP programming can be more
appropriately implemented
if
the user develops the I/O
channel command programs for the 270I/2845 operation.
This publication provides programming information about
the I/O channel commands used with the 2265/2845.
These commands can be implemented through the
EXCP
(Execute Channel Program) macro instruction offered in
each
of
the System/360 programming systems. This
publication includes sufficient information for user pre-
paration
of
the I/O channel program. Also, the user
of
the various programming-support packages will find this
publication helpful.
FEATURES
Several features may
be
installed in the 2265/2845 display
system. In certain cases, the feature
is
required
to
make
the system function. These features must be specified by
the customer and are, therefore, referred
to
as
Specify
features.
An
example
of
a Specify feature
is
the Display
Fonnat Feature. Other features are optional and, when
installed, expand the capabilities
of
the system. These are
referred
to
as
special features. An example
of
a special
feature
is
the Printer Adapter Feature. Although this
special feature
is
not essential
to
the display system oper-
ation, it does expand the system's capability
to
include
control
of
an output printer. Both types
of
features are
described more fully below. All features are summarized
in Figures 14 and
15
of
Appendix
A.
Specify Features
One each
of
the following features must be installed in
the 2845 Display Control. (The number appearing in
parentheses after the feature name
is
the feature number.)
Data
Set
Adapters
The 1200-bps (bits per second) and 2400-bps data set
adapters provide
all
the controls necessary to communicate
with the System/360 channel by means
of
appropriate data
sets and channels
via
an
IBM
2701 Data Adapter Unit.
These control functions include synchronization and
recognition
of
special communications-channel-line-control
characters, decoding and temporary storage
of
commands,
and transfer
of
data and control information between the
2845 display buffer and the attached data set. To interface
with the appropriate data set (see "Data Sets"), one
of
the
following data set adapters must be specified: I
Data
Set
Adapter(9012). This adapter permits attachment
of
the 2845 to a data set operating at a,speed
of
1200 bps;
it also provides the necessary clocking.
Data
Set
Adapter(9013). This/adapter permits attachment
of
the 2845
to
a data set operating at a speed
of
2400 bps.
Clocking must be provided by the data set.
Display
Format
Features
The characters displayed on the Display Station screen may
be presented in one
of
two display image formats. One
format displays
15
lines
of
64 characters each; the second
format displays 12 lines
of
80 characters each. With either
format, the total number
of
characters that may be dis-
played
is
960. One
of
the features described in the follow-
ing two paragraphs must be chosen
to
display the desired
format.
Display Format (9101). This display format uses a large
character with a horizontal character step
of
0.16 inch and
a vertical line step
of
0.32 inch to display
15
rows
of
64
characters
..
The resulting display frame measures nominally
10.3 inches by 4.6 inches.
Display Format (9102). This display format uses a some-
what smaller character than the 9101, with a horizontal
character step
of
0.13 inch and a vertical character step
of
0.26 inch to display 12 rows
of
80 characters. The resulting
display frame measures nominally 10.3 inches by 3.0 inches.
World Trade Language Features
World Trade models must have one
of
the World Trade
Language Features installed. The language feature provides
the 2265 and 2845 with equipment labels and a character
generator appropriate to the language specified. See
Appendix A for feature numbers and Appendix B for
World Trade label, indicator and switch translations, and
unique character codes.
Voltage Features
A voltage feature must be specified for U.S. (Domestic)
and World Trade models
of
the 2265 and 2845. These
features are summarized (with feature numbers) in
Figures 14 and
15
of
Appendix
A.
Special
Features
The following special features may be selected at the
option
of
the customer. (The number in parentheses
following the feature name
is
the feature number.)
Alphameric Keyboard Feature (4766)
This feature permits the operator
to
key in data
at
the
Display Station for display and/or transmission
to
the
central computer.
When
a 1053 Printer
is
attached
to
the
2845, the keyboard also permits a paper copy
of
the dis-
played data to be printed.
As
World Trade options, keyboards are available in
four languages.
When
a keyboard
is
selected, it
is
pro-
vided in the same language
as
specified under the World
Trade Language feature. (See Figures 16, 17, and
18
in
Appendix B for layout
of
keyboards.)
1053 (Printer)
Adapter
Features
A 1053 adapter feature controls the printing
of
informa-
tion by the
IBM
1053 Printer. The information
to
be
printed may originate
at
the central processor and be
addressed specifically
to
the Printer, or the information
may
be
that
which
is
currently being displayed on a
2265 Display Station screen. In the latter case, the 1053
Adapter Feature controls the transfer
of
displayed data
to
the Printer
to
obtain a permanent record
of
the data. The
following two adapter features are mutually exclusive, and
their sele.ction depends upon which Display Format Feature
is
installed.
1053AdapterFeature (7927). This feature permits
attachment
of
an
IBM
1053 Printer
to
a 2845 Display
Control equipped with Display Format Feature 9101.
It
allows printing
of
messages
of
up
to
240 characters from
the computer.
It
also allows printing
of
messages displayed
on a 2265 screen in the 15-rows-of-64-characters format.
1053AdapterFeature (7928). This feature permits the
attachment
of
an
IBM
1053 Printer
to
a 2845 Display Con-
trol equipped with Display Format Feature 9102.
It
allows printing
of
messages
of
up
to
240 characters from
the computer.
It
also allows printing
of
messages displayed
on a 2265 screen in the 12-rows-of-80-characters format.
Note: The 1053 Printer supplied for World Trade use with
the 2845 must have the appropriate World Trade language
feature. The print ball supplied contains characters unique
to
the language specified.
I
Line Addressing Feature (4801)
The line addressing feature permits the program to select
the location on the 2265 screen at which a display message
will start. The display starting locations coincide with the
first character position
of
each row (line)
of
the 2265
Introduction 9
screen. The line address
is
included
as
part
of
the message
transmitted under the Write Line Address command and
is
described under "Principles
of
Operation".
Destructive Cursor Feature (3301)
When
this feature
is
installed in the 2845, the destructive
cursor symbol replaces the standard nondestructive cursor
symbol
as
the display position marker. The destructive
cursor symbol appears on the 2265 screen
as
a horizontal
bar (
_).
The cursor marks the display position that the
next character will occupy. From the 2265 keyboard, the
cursor may be backspaced or advanced one space
at
a time,
moved up
or-
down, or moved to the beginning
of
the next
line. Any character occupying the position
to
which the
destructive cursor
is
moved
is
deleted. (Further infor-
mation concerning
both
the destructive and nondestructive
cursors
is
found under "Special Symbols.")
Tab
Feature (7801)
This special feature permits keyboard indexing
of
the
cursor. Depressing the
TAB
key initiates a search for a
colon. Upon detection
of
a colon, the cursor
"is
reposi-
tioned to the character position immediately following the
colon. When the nondestructive cursor
is
used, there
is
no
change in the display other than the repositioning
of
the
cursor. When the Destructive Cursor Feature
is
installed
any character located in the position immediately
follO\~ing
the colon
is
replaced by the destructive cursor. This
.replacement and the repositioning
of
the cursor are the only
changes in the display.
New Line (NL) characters have no effect
on
the tab
operation. Character locations
to
the right
of
an NL
character are also searched for the presence
of
a colon.
SYSTEM CONFIGURATION
Figure 1
is
a block diagram
of
a possible 2265/2845 con-
figuration. A basic system
is
the same except that the
1053 block would be absent. The 2265/2845 display
system
is
program-compatible with the
IBM
2848 Display
Control, Models 1,
2,
and 3, equpped with the Data Set
Adapter. The{efore, the 2848
as
well
as
the 2845 may be
attached
to
the same communications channel in a
multidrop (multistation) configuration.
10
DATA
SETS
One
of
the data sets described in the following paragraphs
is
required to interface the 2845 Display Control with the
communications channel.
U.S.
(Domestic) Operation
In U.S. (Domestic) operation, the 2845 Display Control
operates at 1200 or 2400 bps, point to point and multi-
point.
For 1200-bps operation, four-wire Telephone Company
or Western Union Type 3002 four-wire duplex facilities
with C1Conditioning*
is
required. Western Electric Data
Set 202DI*
is
specified. Clocking
is
provided by the 2845.
For 2400-bps operation, four-wire Telephone Company
or Western Union Type 3002 four-wire duplex facilities
with
C2
Conditioning*
is
required. Western Electric Data
Set
201
B1*
is
specified. Clocking
is
provided by the data
set.
World Trade Operation
Operation with the following data sets (modems) in a
point-to-point or multipoint configuration over four-wire
service
is
at 1200 bps only:
IBM
3976 Modem Model 3
I
IBM
3977 Modem Model
2.
Like modems must be used in a given configuration.
TYPICAL DISPLAY SYSTEM OPERATION
The 2265/2845 display system provides a rapid and
efficient means
of
two-way communication with the
remotely located central processor. The extent and
flexibility
of
data manipulation
is
a function
of
the Specify
and special features installed in a given display system.
Following
is
a brief description
of
a typical display system
operation. '
Assume, initially,
that
the Display Station screen
is
blank except for a Start
of
Message
symbol (
~)
in the
first character position and a character position marker
(-),
called a cursor, in the second character position in
the upper left corner
of
the display screen. The operator
simply keys in a message on the typewriter-like keyboard.
As
each key
is
depressed, the corresponding character
is
stored in a buffer in the 2845 and simultaneously
dis-
played on the 2265 screen.
As
each character
is
keyed in,
the cursor advances one display position. The cursor thus
serves
as
a marker
to
indicate the display position the next
character will occupy on the screen. When the message
is
*or equivalent
Note:
A maximum
of
sixteen
2845's
may
be
multi-dropped
on
one
communications
channel.
___
Communications
Channel
Figure
1.
Typical Connection
of
an
IBM
2845 Display Control to a Remote Central ProcessorShowing Application
in
a
Multidrop Communications Network.
complete, the operator visually verifies the message and
then depresses the ENTER key. At the same time, the
Ikeyboard locks and the ENTER PENDING indicator on the
keyboard lights. The next time the Display Station
is
polled
by the central processor, the completed message
is
auto-
Imatically transmitted to the processor. The ENTER
PENDING indicator remains lit until the polling operation
has been successfully terminated. When the indicator turns
off, the Start
of
Message
(SOM)
symbol disappears, the
keyboard unlocks, and the operator
is
free to key in another
message.
Under program control at the central processor, messages
may also be sent from the central processor
to
the 2845
and displayed on the Display Station screen. Characters
of
the message text are displayed on the screen, beginning at
the character position currently occupied by the cursor.
If
the Display Control
is
equipped with the Line Addressing
feature, the program may designate that the first character
be displayed in the first character position
of
a specified
line.
By
the use
of
various commands, the program may
erase
all
data from the Display Station screen or may
caUse·
all
data stored in the display buffer
to
be
transmitted to the
central processor.
Tlie
screen may also be erased by the Display Station
operator. In addition to being able to erase the complete
screen, the operator may selectively erase
all
data from the
cursor to the end
of
that line or from the cursor to the end
of
the screen. The operator may erase any character or
replace
it
with another simply by positioning the cursor
to the described character location and depressing the
I SPACE/ERASE-ADVANCE bar (to erase the character) or
Introduction
11
·depressing a different character key
(to
replace the charac-
ter). Rapid positioning
of
the cursor
by
the operator
is
also provided.
By
depressing the proper key, the cursor may
be moved up, down, left, or right.
The functions
of
the commands and keyboard keys are
described in detail later in this publication.
OPERATION WITH 1053 PRINTER
When a 1053 Printer is attached
to
the Display Control,
the data displayed
on
a 2265 screen can be printed
by
depressing the PRINT key on the 2265 keyboard. All data
from the first displayable character position
of
the screen
up
to
the character position occupied by the cursor (except
for those characters
to
the right
of
and
on
the same line
as
the NL character) are transferred
to
the Printer. Detection
of
the
EOM
symbol ends the print operation immediately
after the
EOM
symbol is printed. Because the
EOM
symbol
may be displayed
to
the right
of
an NL symbol, all charac-
ter positions
to
the right
of
an NL symbol are searched for
an
EOM
symbol even through the characters displayed in
these positions are
not
printed. (The
EOM
symbol itself
is
printed.)
If
an internal parity error occurs within the 2845 after
a keyboard print operation
is
initiated and before the
operation
is
terminated, a Check symbol
('
)
is
printed
as
the last character
of
the printed text. The Check symbol
notifies the operator
that
an internal parity error has been
detected,
but
does
not
identify the character(s) involved.
The parity error may have occurred in either the display
buffer
or
the printer buffer. In any case, all characters are
printed
as
they exist in the display buffer.
Remotely,
by
means
of
a Write Printer command, the
central processor may send a message
of
up
to
240
characters via the 2845
to
the 1053 Model 4 Printer. The
entire message
is
received and stored in the printer buffer
of
the 2845 before
it
is
transferred
to
the Printer.
If
an
error
is
detected during message transmission, transfer
to
the Printer is inhibited and the entire message must be
retransmitted. If, however, no errors are detected in
transmission, receipt
of
the final message character initiates
transfer
of
the message
to
the Printer and printing com-
mences.
As
in the keyboard PRINT key operation, detection
of
an internal parity error, either in the printer buffer or
display buffer
of
the 2848, causes a Check symbol
to
be
printed
as
the last character
of
the printed message. The
Check character simply indicates
that
an error has been
detected within the 2845
but
does
not
identify the
character(
s)
involved.
A message
of
up
to
240 characters may be sent by-the
central processor
to
the Printer via the 2845. A Printer
message
of
greater length may be sent
to
the Display
Station, with the operator instructed (as part
of
the
message)
to
execute a keyboard Print operation. Or,
th~
12
message may be sent in individual Write Printer trans-
missions
of
240 characters or less directly to the Printer.
During transmission from the central processor
to
the
Printer, data displayed
on
the display screen is
not
affected.
The 1053 Piinter, when controlled
by
the 2845,
is
equipped with a special print element
that
permits printing
of
the
SOM,
EOM,
and Check symbols. Therefore, all
characters are printed
as
they exist in the printer buffer.
However, the NL symbol
is
not
printed; rather,
it
causes
a carriage return/line feed (CR/LF) operation.
2265 DISPLAY STATION OPERATOR CON'FROLS
AND INDICATORS
Operator controls on the 2265 Display Station
(not
including those located on the keyboard) are a POWER
ON
switch/indicator, a POWER OFF switch, and a
Brightness control.
(A
single POWER ON/OFF switch
is
the only control on the 2845 Display Control accessible
to
the operator.)
The POWER
ON
switch/indicator is located
on
the front
right side
of
the 2265. Upon depression
of
this switch/
indicator, all voltages required for operation are supplied
to
the 2265 and 2845 provided the 2845 POWER ON/OFF
switch
is
set
to
ON.
When all power
is
on in
both
units,
the 2265 POWER ON switch/indicator lights. Voltages
necessary for operation are turned
off
in
both
units when
either the 2265 POWER OFF switch (located immediately
below the POWER ON switch/indicator)
is
depressed or
when the 2845 POWER ON/OFF switch is flipped
to
OFF.
(A 49V source, located in the 2845,
is
energized and
supplies 49V
to
the 2265 when the 2845 POWER ON/OFF
switch
is
ON regardless
of
the
condition
of
the 2265.
power switches. However, other voltages,
off
at this time,
are required
to
make
both
units operational.)
The Brightness control
is
located immediately above
the POWER
ON
switch/indicator on the 2265. Rotating
the Brightness control knob clockwise increases the
brightness
of
the characters displayed
on
the screen, thus
enabling the operator
to
adjust the brightness
to
a com-
fortable viewing level.
Two indicators are located
on
the 2265 keyboard. The
DATA SET READY indicator notifies the Display Station
operator
that
the attached data
sethas
power
on
and is
Iready
to
function. The ENTER PENDING indicator
informs the operator
that
an Enter operation
is
pending.
I
While
the ENTER PENDING indicator
is
lit, the keyboard
is
locked. The ENTER PENDING indicator lights when the
ENTER key
is
depressed and
is
extinguished when one
of
the following occurs:
1.
Polling
of
the Display Station
is
successfully terminated.
2. The RESET key is depressed before 2845 recognition
of
a specific or general poll.
13. Any other command (except Read Addressed Full
DS
Buffer) precedes the polling operation.
A TEST key enables the operator to quickly test the
display system. By observing the display screen, a judgment
may be made
as
to the operational status
of
the 2265 and
2845. The test procedure
is
described fully under "Display
System Test Procedure".
DISPLAY STATION KEYBOARD
Images
to
be displayed on the 2265 Display Station screen
may be initiated
at
the Display Station keyboard (Figure
2). Through use
of
the keyboard data character and
control keys, the operator may compose the text
to
be
displayed and may communicate with the 2845 regarding
disposition
of
the text.
.
Character
Keys
The characters that may be displayed consist
of
26
uppercase alphabetic characters, 10 numeric characters,
and 23 punctuation (or special) characters. Operation
of
any
of
the character keys causes the selected character
to
be displayed on the screen in the character position
occupied by the cursor.
Control
Keys
See
Tables 1 and 2 for a listing
of
the 2265 control keys
and their functions. Note that rapid cursor positioning can
Ibe performed by the SPACE/ERASE-ADVANCE and
BKSP
(Backspace) keys. That is, when any
of
these keys
are depressed
to
their final stop, the operation
of
the key
is
continuously repeated at about nine characters per
second
as
long
as
the key
is
held depressed (unless inter-
rupted by an I/O operation).
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Special
Symbols
The special symbols described in the following paragraphs
can be displayed on the screen
of
the 2265.
Cursor-General Description
The cursor
is
an automatically inserted visual display
position marker;
it
denotes the display position on the
2265 screen
that
the next character entered will occupy.
Two types
of
cursor symbols, nondestructive and destruc-
tive,
are
available
to
permit selection
of
the cursor best
suited
to
individual applications. Both are described below.
Nondestructive Cursor
Symbol
(Standard)
The nondestructive cursor symbol appears
as
_.
It
indicates
the character position
to
be occupied by the next character
entered on the display. The nondestructive cursor symbol
appears on the 2265 screen below the character line and
immediately below the character position the next character
entered will occupy. Since the nondestructive cursor
symbol occupies a display area below the character line,
it
may be moved about freely on the 2265 screen without
interfering with other characters. Table 1 explains the
effect that each 2265 keyboard key has on the nondestruc-
tive cursor symbol.
The movement
of
the nondestructive cursor symbol and
its position relative
to
other display characters during the
time the data
is
entered from the 2265 keyboard are
described under "Control Key Functions." Also,
see
Programming Note under "Destructive Cursor Symbol
(Feature)".
ENTER
DATA
SET
PENDING
READY
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II
SPACE/ERASE
A15vANCE
eFigure 2. Display Station Keyboard
Introduction
13
Table
1.
Functions
of
2265 Display Station Keys (Nondestructive Cursor)
Key
No
Shift
Shift
Single-Character Keys
Cause
symbol
to
be displayed. Keyboard locks.
No
character
is
entered.
Keyboard may be unlocked
by
depressing
RESET key.
Double-Character Keys
Cause
symbol on lower half
of
key
to
be
displayed.
Cause
symbol on upper
half
of
key
to
be
displayed.
ENTER
Places
EOM symbol in cursor position. Cursor does Same
not
move. Keyboard locks and
ENTER
PENDING
light
is
lit. Upon receipt
of
Specific Poll
or
General
Poll command, all data between.SOM
and
EOM
is
sent
to
computer.
If
this
data contains
an
NL
symbol, data between NL symbol and end
of
line
containing
it
is
not
sent.
If
EOM
is
placed
to
right
of
NL
symbol, all data
between SOM and
the
NL symbol immediately
preceding EOM is sent.
If
no SOM is displayed, a zero-length
message
is
transmitted.
After
successful
message
transmission resulting
from
a poll, cursor and EOM symbols remain
unmoved,
but
SOM
is
deleted. Keyboard unlocks
and ENTER PENDING light
is
extinguished.
\
If
Write Addressed
DS
or
Erase/Write Addressed
DS
command is honored before a
poll
command,
first
character
of
text
over-writes EOM symbol.
When
command
is
concluded, keyboard
is
unlocked and
ENTER PENDING light
is
extinguished. Enter
operation is ended.
If
Write
DS
Line Address command is honored be-
fore a
poll
command, EOM symbol
mayor
may
not
be
over-written depending
on
line addressed and
length
of
text.
When command is concluded, key-
board
is
unlocked and
ENTER
PENDING light
is
extinguished.
If
Read
Addressed
Full
DS
Buffer
command
is
honored
before a
poll
command, no change occurs on screen.
I When command is concluded, keyboard remains
locked and ENTER PENDING
light
is
on, indicating
Enteroperation still pending.
PRINT
Places
EOM symbol
in
cursor position.
Causes
all
Same
data
from
first
character poSition
in
first
line
to
and including
the
EOM symbol
to
be
printed
by
the
1053Printer. Exceptions are
NL
symbols and data
to
right
of
and
on
same
line
as
NL
symbols. How-
ever,
an
eOM
symbol located
to
right
of
NL
symbol
is
printed. Keyboard
is
locked during
print
opera-
tion.
If
2845 is
not
equipped
with
Printer Adapter Feature,
no operation occurs.
NEW
LINE
Cursor moves
down
one line.
If
it
is already
in
bottom
Places
NL symbol in cursor position.
DOWN line,
it
moves
to
top
line. Lateral position
of
cursor Cursor moves
to
first
character position
within
display remains constant.
of
next-lower display line.
If
cursor
is
already
in
bottom
line,
it
moves
to
first
character position
of
top
line.
Data between
NL
symbol and
end
of
line
is
left
undisturbed.
SHIFT
Permits
function
shown in
"Shift"
column
for
control
Same
keys,
or
enables selection
of
special character on upper
half
of
keys.
14
I
I
Table
1.
Functions
of
2265 Display Station Keys (Nondestructive Cursor) (Cont)
Key
No
Shift Shift
SPACE/ERASE Advances cursor one character position, with
no
Erases character position
to
right
of
cur-
ADVANCE* other modification
of
display.
If
cursor
is
already sor and advances cursor one character
in
last character position
of
bottom
line, it moves position.
If
cursor
is
already
in
last char-
to first character position
of
top
line. acter position
of
bottom
line, it moves
to
first character position
of
top
line.
BKSP
(Backspace)* Backs cursor
by
one position with
no
erasures. Same
If
cursor
is
in
first character position
of
screen,
it moves
to
last character position
of
screen.
START Cursor moves up one line
on
display.
If
cursor
is
1.
If
no
SOM
symbol
is
displayed else-
UP
in
top
line, it moves
to
last line. The lateral posi- where on screen, an
SOM
symbol
is
tion
of
the
cursor within
the
display remains placed
in
position occupied by cursor
constant. when key
is
depressed. Cursor
is
ad-
vanced one character position.
2.
If
an
SOM
symbol
is
already being
displayed when key
is
depressed, all
display data between existing
SOM
symbol and cursor (except data
on
same line as and
to
right
of
an
NL
symbol)
is
erased. Cursor moves
to
first character position following
existing
SOM
symbol.
3.
If
an
SOM
symbol
is
already being
displayed and if cursor
is
in
same char-
acter location as
SOM
when key is
depressed, cursor
is
advanced one
character position.
No
further
change occurs.
In
the
preceding cases, cursor
position identifies first character
that
will be transmitted by 2845 upon
depression
of
ENTER key.
4.
If an
SOM
symbol
is
already being
displayed and if cursor
is
to
right
of
and on same line
as
an NL symbol
when key
is
depressed, all display
data
is
erased starting with position
immediately following
SOM
symbol.
Erase continues, observing
NL
sym-
bols as
in
2, until
SOM
is
erased.
Cursor ultimately occupies same
position as when key was depressed.
RESET
Key
is
ineffective during time a command Same
(except Write Printer)
is
in
process.
Following the attempted execution
of
an
invalid keyboard operation, termination of
a command operation with
other
than STX/
EOT,
or
detection by 2845
of
an internal
parity error (resulting
in
keyboard lockup),
restores keyboard operation. When depressed
after ENTER key depression
but
before
Specific Poll
or
General Poll command
is
received, cancels Enter operation and
un-
locks keyboard.
No
change in displayed
image occurs.
When depressed after PRINT key has been
depressed, causes immediate end
of
print
operation and unlocks keyboard. Cursor
moves
to
display position immediately
following last character transferred
to
1053
Printer.
*Rapid cursor positioning may be performed with this key.
That
is,
if depressed to its final stop,
the
key's operation
is
repeated
at
about
nine characters per second
as
long as
the
key
is
held depressed.
Introduction 15
I
Table
1.
Functions
of
2265 Display Station Keys (Nondestructive Cursor) (Cont)
Key
No
Shift Shift
ERASE
DPLY
Erases entire display, places an
SOM
symbol Same
(Erase Display)
in
upper left corner
of
display (first display-
able character position), and cursor
in
second
character position.
ERASE
E0L
Erases
all
characters, beginning with position
in
Same
(Erase
to
End of Line) which cursor
is
located and continuing
to
end
of
that
line. Cursor does not move. ,
Erase
EOS
Erases
all
characters, beginning with position
in
Same
(Erase
to
End of Screen) which cursor
is
located and continuing
to
end
of
screen. Cursor does not move.
TEST Isolates 2845 data set and initiates internal Same
"wrap"
test.
TAB Initiates a search for a colon. Search begins Same
with cursor's present position. When a colon
is
detected, cursor
is
positioned
to
character
position immediately following colon.
No
characters are erased.
If
no colon
is
detected before end
of
screen
is
reached, cursor
is
positioned
to
upper
left corner
of
display (first displayable
character position).
NL
symbol has no effect on
tab
operation.
If
no Tab feature
is
installed, no operation
occurs.
Destructive Cursor Symbol (Feature)
The destructive cursor symbol appears on the screen
of
the 2265
as
a heavy horizontal bar
(-);
it marks the
display position
that
the next character entered will occupy.
Table 2 explains the effect
of
each keyboard key on the
destructive cursor symbol. When the destructive cursor
is
advanced, backspaced, or otherwise moved
to
a character
position containing a character, the character
is
erased.
The movement
of
the destructive cursor symbol and its
position relative
to
other display characters during the
time data
is
entered from the 2265 keyboard are described
under "Control Key Functions".
PROGRAMMING NOTE: Whether the nondestructive cursor
symbol
or
the destructive cursor symbol is being used
as
a 2265
display position marker, the
EOM
symbol will appear on
the
2265
screen in
the
position occupied by the cursor when the keyboard
ENTER key
is
depressed (as in manual input operations)
or
when
the PRINT key
is
depressed.
To ensure correct manual input operations when the
nondestructive cursor
is
used, the
EOM
symbol should be
deleted from the 2265 screen between message transfers.
This can be accomplished through programming (by issuing
an Erase/Write following a Poll command) or by the
operator at the keyboard (by overwriting the
EOM
symbol).
End
of
Message
(EOM) Symbol
Whether or not the 2845
is
equipped with the Destructive
Cursor Feature, the
EOM
symbol
(_)
designates the end
of
a message. In appearance it
is
identical with the
destructive cursor symbol. The
EOM
symbol
is
displayed
by depressing the ENTER key or the PRINT key or by
transmitting
-the
EOM
code from the I/O channel to the
2265. The latter course should be avoided since the
presence
of
both
an
EOM
symbol and a destructive cursor
symbol can be confusing to a viewer and can cause an
operation
to
be prematurely terminated. However, when
a message
is
transmitted from the I/O channel
to
the 1053
Printer, the
EOM
code should be transmitted
as
the last
character
to
denote the end
of
the message. The
EOM
code
is
printed by the 1053 Printer
as
an
EOM
symbol and
it also causes a 1053 carriage return/line feed function.
The differences between an
EOM
symbol and the
destructive cursor symbol are:
1.
The cursor denotes the display position that the next
character entered will occupy. The
EOM
symbol
denotes only the end
of
a message.
2.
The cursor advances
as
data
is
entered and can be moved
about the 2265 screen. The
EOM
symbol, when
dis-
played, remains stationary.
3.
The cursor
is
automatically inserted and
is
displayed
at all times. The
EOM
is
displayed only when the
ENTER or PRINT key
is
depressed or when its code
is
transmitted from the I/O channel
to
the 2265.
4.
Only one cursor symbol may be validly displayed on
a 2265 screen, whereas
it
is
possible to display
multiple
EOM
symbols.
While
the viewer must rely on operation observation
to
distinguish the destructive cursor from
an
EOM
symbol, the distinction within the 2845 Display Control
is
performed electronically.
16
Table
2.
Functions
of
2265 Display Station Keys (Destructive Cursor)
Key
Single-Character Keys
Double-Character Keys
ENTER
PRINT
I
NEW
LINE
DOWN
SHIFT
No
Shift
Cause symbol
to
be displayed.
Cause symbol on lower half
of
key
to
be displayed.
Keyboard locks and ENTER PENDING light
is
lit.
Upon receipt of Specific Poll
or
General Poll command,
all
data between
SOM
and
EOM
is
sent
to
computer.
If
this data contains an
NL
symbol, data between
NL
symbol and end
of
line containing it
is
not sent.
If
EOM
is
placed
to
right
of
NL
symbol,
all
data
between
SOM
and
the
NL symbol immediately
preceding
EOM
is
sent.
If
no
SOM
is
displayed, a zero-length message
is
transmitted.
After successful message transmission resulting
from a poll, cursor remains unmoved,
but
SOM
is
deleted. Keyboard unlocks and ENTER PENDING
light
is
extinguished.
If Write Addressed
OS
or
Erase/Write Addressed
OS
command
is
honored before a poll command,
first character
of
text
overwrites
EOM
symbol.
When command
is
coneluded, keyboard
is
unlocked
and ENTER PENDING lightisextinguished. Enter
operation
is
ended.
If
Write
OS
Line Address command is honored
before a poll command,
EOM
symbol
mayor
may
not be overwritten depending
on
line addressed
and length
of
text. When command
is
concluded,
keyboard-is unlocked and ENTER PENDING light
is
extinguished.
If
Read Addressed Full
DS
Buffer command
is
honored before a poll command, no change occurs
on screen. When command
is
concluded, keyboard
remains locked, ENTER PENDING light
is
on,
indicating Enter operation still pending.
Causes
all
data from first character position
in
first line
to
and including cursor
to
be printed by
1053 Printer.
Exceptions.re
NL
symbols and
data
to
right
of
and
on
same
Une
as
NL
symbols.
However, an
EOM
symbol located
to
right of
NL
symbol
is
printed. Keyboard
is
locked during print
operation.
If
2845
is
not
equipped
with
Printer Adapter Feature,
no operation occurs. .
Cursor moves down one line. If it
is
already
in
bottom
line, it moves
to
top
line. Lateral position of cursor
within display remains oonetant. Destructive cursor
replaces any character occupying character position
into which it moves. Previous position occupied
by
cursor
is
displayed as a
~.
Permits function shown in
"Shift"
column for
control keys,
or
enables selection
of
special character
on upper half
of
keys.
Shift
Keyboard locks. No character
is
entered.
Keyboard may be unlocked by depress-
ing
RESET key.
Cause symbol on upper half
of
key
to
be
displayed.
Same
Same
Places NL symbol
in
cursor position.
Cursor moves
to
first character position
of
next-lower display line. If cursor
is
already
in
bottom
line, it moves
to
first character position
of
top
line.
Data between NL symbol and end
of
line
is
undisturbed.
Same
Introduction
17
Table 2. Functions
of
2265 Display Station Keys (Destructive Cursor) (Cont)
Key
No
Shift Shift
SPACE/ERASE Advances cursor one character position. Cursor Same
ADVANCE* replaces character (if any)
in
position into which it
moves. Previous position occupied by cursor
is
displayed as a space.
BKSP*
(Backspace) Backs cursor by one position, erasing character (if Same
any) previously displayed
in
new cursor position.
If
cursor
is
in
first character position, it moves
to
last character position.
A space
is
displayed in position previously oc-
cupied by cursor.
START Cursor moves up one line
on
display.
If
cursor
1.
If
no
SOM
symbol
is
displayed else-
~
is
already
in
top
line, it moves
to
last line. where
on
screen, an
SOM
symbol
is
The lateral position
of
cursor in
the
display
re-
placed
in
position occupied by cursor
mains constant. when key
is
depressed. Cursor is ad-
vanced one character position.
Cursor replaces character
in
new position and 2. If
an
SOM symbol
is
already being dis-
a space
is
displayed
in
position previously oc- played when key
is
depressed, all
dis-
cupied
by
cursor. play data between existing
SOM
symbol and cursor (except data
on
same line as and
to
the
right
of
an
NL symbol)
is
erased. Cursor moves
to
first character position following
existing
SOM
symbol.
3. If an
SOM
symbol
is
already being
displayed and if cursor
is
to
right
of
and
on
same line as an NL symbol when
key
is
depressed,
all
display
data
is
erased starting with position immedi-
ately following
SOM
symbol. Erase
continues, observing
NL
symbols as
in
2, until
SOM
is
erased. Cursor ulti-
mately occupies same position as
when key was depressed.
In all cases cursor position identifies
first character
that
will be transmitted
by 2845 upon depression of ENTER
key.
RESET
Key
is
ineffective during time a command (except Same
Write Printer)
is
in
process.
Following attempted execution of an invalid key-
board operation, termination
of
a command oper-
ation with
other
than
STX/EOT, or detection by
2845
of
an internal parity error (resulting
in
key-
board lockup), restores keyboard operation.
When
depressed after ENTE R key
is
depressed
but
before Specific Poll
or
General Poll com-
mand
is
received, cancels Enter operation and
unlocks keyboard.
No
change in displayed image
occurs.
When
depressed after PRINT key has been
depressed, causes immediate end
of
print opera-
tion and unlocks keyboard. Cursor moves
to
display position immediately following last
character transferred
to
1053 Printer.
*Rapid cursor positioning may
be
performed with this key.
That
is,
if
depressed
to
its final stop,
the
key's
operation
is
repeated
at
about
nine characters per second
as
long as the key is held depressed.
18
I
Table
2.
Functions
of
2265 Display Station Keys (Destructive Cursor) (Cont)
Key
No
Shift Shift
ERASE
DPl
Y (Erase Display) Erases entire display. Places an SOM symbol
in
Same
upper left corner
of
display (first displayable
character position), and cursor
in
second char-
acter position.
ERASE
EOl
Erases all characters, beginning with position Same
(Erase
to
End
of
Line) immediately following
that
in
which cursor
is
located
and
continuing
to
end
of
that
line.
Cursor does
not
move.
ERASE EOS Erases all characters, beginning with position Same
(Erase
to
End of Screen) immediately following
that
in
which cursor
is
located and continuing
to
end
of
screen.
Cursor does
not
move.
TEST Isolates
2845
data
set and initiates internal Same
"wrap"
test.
TAB Initiates a search for a colon. Search begins Same
with position immediately following cursor.
When a colon
is
detected, cursor is positioned
to
character position immediately following
colon. If any character
is
already being dis-
played
in
this position, it
is
replaced
by
the
cursor.
No
intervening characters are erased
or
modified.
If no colon
is
detected before end
of
screen,
cursor
is
positioned
to
upper left corner
of
display (first displayable character position).
If
any
character
is
already being displayed
.
in
this position, it
is
replaced
by
cursor.
Nl
symbol has no effect on tab operation.
If no Tab feature
is
installed, no operation
occurs.
New Line (N
L)
Symbol
Start
of
Message
(SOM) Symbol
The
SOM
symbol (
~)
is
used
to
indicate the beginning The NL symbol
(~
), when displayed on the 2265 screen,
prohibits the transfer
of
all
data displayed between the
of
data that
is
to
be transferred from a display buffer to
the I/O channel during a Specific Poll or General Poll
operation.
If
data
is
to
be transferred during one
of
these
operations, the
SOM
symbol must be displayed on the
2265 screen before the data to be transferred. Upon
successful completion
of
either operation, the
SOM
symbol
is
automatically deleted from the 2265 screen. Deletion
of
this symbol signifies to the 2265 operator that the data
has been successfully transferred from the display buffer
and that another message may
be
entered.
The
SOM
symbol
is
made to appear on a 2265 screen
by depressing the START key on the keyboard
of
the
2265 or by transmitting the code configuration
of
the
symbol from the I/O channel to the 2265. For additional
information concerning the
SOM
symbol, refer
to
the
description
of
the above operations under "Principles
of
Operation" and "2265 Display Station Keyboard Oper-
ations."
NL symbol and the end
of
the display line containing the
symbol during a Specific Poll or General Poll operation.
The NL symbol may be either keyboard- or program-
inserted;
it
enables transfer
of
only a portion or portions
of
data displayed on the 2265 screen during either
of
the
above operations. The effect
of
depressing the
NEW
LINE
key
is
described in Tables 1 and 2.
Check Symbol
The Check symbol ( , )
is
used to indicate detection
of
a
parity (YRC) error in transmission
of
data to the 2845
display buffer during a Write operation. When a character
with incorrect parity
is
detected by the 2845 Display
Control during a Write operation, a Check symbol
is
dis-
played in place
of
the character in error. The Check
symbol carfruso be displayed by transmission
of
the code
configuration for the Check symbol from the I/O channel
to the 2265.
Introduction 19
A single parity bit
is
assigned
to
two characters in the
2845 buffer storage.
As
a result,
if
a buffer parity error
is
detected within the 2845, two Check symbols are
dis-
played on the 2265 screen since' either character.may be
in error. See Figure 3. Due to the storage method used,
these Check symbols appear exactly eight lines apart in
the
15
x 64 display format (6 lines apart in the 12 x 80
display format) and in the character positions immedi-
ately following the characters in which the parity error
occurred.
If
either
of
the display positions following the
possible characters in,error contains a character, the
Check character will replace that character.
If
the
15
x 64
display format
is
used, a parity error occurring in the
eighth display line will display one Check character on
that line only. A second Check character
is
not
displayed
elsewhere on the screen since no 16thline
is
displayed.
Upon display
of
the Check characters, the keyboard is,
in effect, locked. That is, the next attempted keyboard
entry locks the keyboard, and the character
is
not entered
into the display buffer nor displayed. Thus the operator
receives a positive indication that an error has been
detected. Following operator verification
of
the cause
of
the locked keyboard, the keyboard
maybe
restored
(unlocked), and keyboard entry resumed, by depressing
the RESET key.
IPROGRAMMING NOTE:
If
a Read Addressed Full
DS
Buffer
command is begun before the keyboard has been stored (RESET
key depressed), a
CAN
character
is
automatically transmitted
following the display buffer contents. No
CAN
character
is
trans-
mitted if
the
RESET key
is
depressed before the read buffer oper-
ation is started. When an internal parity error is detected
by
the
2845 in any character stored in the display buffer, the error is
identified
by
display
of
the check character.
If
an internal parity .
error is detected after the ENTER key is depressed and the Display
Station
is
polled, the
CAN
character is transmitted following the last
character
of
text.
CAN
is
transmitted even though the parity error
did
not
occur in one
of
the characters
of
the Display Station message.
The operator may intervene at any time after the ENTER key
is
depressed
but
before a poll command
is
recognized by the 2848 ifa
check character is noted on the display screen. By depressing the
RESET key, the operator interrupts
the
Enter operation.
If
the
character in error
is
not included in
the
Display Station message
(error affects other data displayed
on
the screen), the ENTER key is
again depressed. These actions prevent the
CAN
character from
being transmitted in the message. However,
if
the check character
appears in the Display Station message, the operator may correct
the error by inserting the proper character and again depressing the
ENTER key.
CONTROL KEY FUNCTIONS
The actions
that
occur when certain control keys are
depressed are described in Tables 1 and 2 for both the
nondestructive and destructive cursor. The display
symbols associated with control key functions, where
applicable, are
as
follows: .
1.
SaM
symbol
~
2.
NL symbol
~
20
3.
Nondestructive cursor
_:
This symbol
is
displayed
immediately below the next displayable position, thus
ABC
_ .
If
the D character key
is
depressed, the
new display will appear
as
ABCD
_ .
4. Destructive cursor
-:
The small horizontal bar
is
the
destructive cursor symbol and denotes the next
available display position, thus
ABC
-.
If
the D
character key
is
depressed, the display will appear
as
ABCD-
The control keys, described in Tables 1 and 2, all
appear on 2265 Display Station keyboards even when the
feature associated with the key
is
not
installed in the
associated 2845 Display Control. For example, the PRINT
key
is
present on the 2265 keyboard even though the
attached 2845
is
not equipped with the Printer Adapter
feature. The data in Tables 1 and 2 for each control key
includes a description
of
the effect
of
depressing the key
when the associated feature
is
not present.
2265 DISPLAY STATION KEYBOARD OPERATIONS
Manual
Input
The following describes the procedures for manually
entering data into the display buffer (from the keyboard)
for transfer
to
the I/O channel during a Specific Poll or
General Poll operation:
1.
Position the cursor in the character position where the
message
is
to begin. Refer to Tables I and 2 to select
a keyboard keyes) that will facilitate positioning the
cursor.
2.
Depress the SHIFT key and simultaneously depress
the START key. This causes the
SaM
symbol
to
be
entered in the display buffer and to appear on the 2265
screen in the character position previously occupied
by the cursor. The cursor
is
advanced
to
the next display
position.
3. Key in the message
to
be transferred
to
the I/O channel.
The message data will appear on the 2265 screen
as
the
character keys are operated. The cursor symbol auto-
matically advances
as
data
is
displayed on the 2265
screen.
4.
After the entire message
is
displayed on the 2265 screen
and
is
Visually
verified, depress the ENTER key. This
causes all the keys on the keyboard except all ERASE
keys, the RESET key, and TEST key
to
be locked, and
initiates an Enter operation. The ENTER key causes the
2845
to
respond
to
a poll command by sending the
display message to the central processor.
5.
Upon successful completion
of
the poll, the keyboard
is
I restored, the ENTER PENDING indicator
is
extinguished,
and the SaM symbol
is
deleted from the screen. These
actions notify the operator that the Enter operation has
concluded with a successful transmission
of
the message.
Another message may now be entered at the Display
Station.
This manual suits for next models
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