Digital Equipment VT420 User manual

First Edition, November 1989
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Copyright © by Digital Equipment Corporation 1989
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Rules,
which are designed to provide reasonable protection against such radio frequency
interference when operated in a commercial environment. Operation of this equipment in
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This document was prepared and published by Educational Services Development and
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Contents
About This Guide
Xl
1 A Look at the Terminal
VT420 Components ............... . . . . . . . . . . . . . . . . . . . . . 1
TerIIlinal .......................................... 1
Keyboard. . ... . .. . .... . . . .. . . . . . . . . . . .. . . . .. . . . . . . . 2
Your
Computer System ................................. 3
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Set-Up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Two Sessions ................................... . . . . 4
Windows................................ .......... . 4
Number of Lines on the Screen . . . . . . . . . . . . . . . . . . . . . . . . . 5
Page Memory
................................... '. . . . 5
Copy and Paste ....................... . . . . . . . . . . .. . . 5
Status Line ........................................ 5
Keyboard Indicator
Line .............................. 6
Screen
Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Screen Background
.................................. 6
Emulating VT Series Text Terminals . . . . . . . . . . . . . . . . . . . . . 6
Character Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Programming the Tenninal ................... . . . . . . . . . . . 8
iii

iv Contents
Installing Your VT420 Video Terminal
2 Installation
Site Considerations 0 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11
Installation 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • 0 • 0 0 0 • 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • 0 12
Cable Connections . 0 0 0 0 0 0 •• 0 • 0 0 0 0 •••• 0 • 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 18
Problem Solving 0 0 0 0 0 • 0 0 • 0 0 0 0 0 • 0 0 0 0 •• 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 22
3 Getting Started
Setting Up the VT420 for One or Two Sessions 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24
Setting Up for One Session (One Cable) o. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24
Setting Up for Two Sessions (Two Cables) .000000000000000 0 26
Setting Up for Two Sessions with SSU Software (One Cable) 00 28
Selecting the Correct Baud Rate 000 0 0 •• 0 0 • 0 0 00 0 0 0 0 0 0 00000 0 30
Selecting the Correct Terminal ID 0 0 0 0 •• 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 31
Using· Your VT420 Video Terminal
4 The Keyboard and Indicators
LK401 Keyboard 0.00000000000000000.000000000000000000 35
Main Keypad 0 0 • 0 0 0 0 • 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 36
Editing Keypad 00.000000. 0 0 0 0 0 •• 0.00000000. 0 0 0 0 0 0 000 39
Nmneric Keypad 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0" 0 0 40
Top-Row Function Keys 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 41
Compose Characters 0 0 0 0 0 0 0 0 0 0 0 0 0 •• 0 0 0 0 • 0 0 0 0 •• 0 0 0 0 0 0 0 44
Indicator Lights 0 0 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 44
Audible Indicators 0 0 0 0 • 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 • 45
Keyclick 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o. 0 0 0 0 0 45
Bell 00. 0 0 • 0 0 0 0 0 0 0 000000000.000 •• 0 0 0 ••••• 0 0 ••• 0 0 000 45
Keyboard Indicator Line . 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 46
Status Line 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • 0 0 0 0 0 0 0 0 • 0 0 0 47
Word Processing Keyboard. 0 0 • 0 .0000000. 0 • 0 0 •••••••••• 0 0 0 50

Contents v
5 Using S~t-Up
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Independent Setups for Two Sessions .................... 52
Entering and Leaving Set-Up ............................ 53
Set-Up Directory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Status Line and Keyboard Indicator Line ................. 54
Set- Up Cursor .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Action Fields
.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Set- Up Directory Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Selecting Set-Up Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Changing and Recalling Settings . . . . . . . . . . . . . . . . . . . . . . . . . . 58
How to
Change Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
How to
Save Your Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
How to Recall
Saved Settings .......................... 59
Global Set-Up
Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Two Sessions .................................. . . . . . 60
Display Set-Up Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
62
Selecting a Page Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Selecting the Number of Lines/Screen . . . . . . . . .. . . . . . . . . . . 62
Coupling the Cursor to the Display . . . . . . . . . . . . . . . . . . . . . . 63
General Set-Up Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Character Sets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Communications
Set-Up Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Keyboard Set-Up
Screen ................................ 74
Ta.b Set-Up Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6 Typing Additional Characters
What Characters Can I Type? .................. . . . . . . . . . . 79
How to Type a
Character Using the Compose Character Key . . . . 80
Invalid Sequences ...................................... 80
Canceling or Restarting a Compose Sequence . . . . . . . . . . . . . . 81
Hexadecimal Compose Sequences ......................... 81

vi Contents
7 Using Two Sessions, Windows, and the Copy and Paste
Feature
What Are Sessions? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
'I'w-o Sessions ......................................... 87
Opening Two Sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
If You Use Two Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
If You Use One Cable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Restoring an Interrupted SSU Session. . . . . . . . . . . . . . . . . . . . 93
SSU Screen and Error Messages . . . . . . . . . . . . . . . . . . . . . . . . 93
Which Session
is Active? ................................ 94
Number of LinesiScreen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
How to
Change the Number of LinesiScreen . . . . . . . . . . . . . . . 95
Windows............................................. 96
One Window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Two Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
How to Select One or
Two Windows . . . . . . . . . . . . . . . . . . . . . . 97
Keeping
the Cursor Visible ............................ 98
How to Change Window Sizes ...... . . . . . . . . . . . . . . . . . . . . 99
Panning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
How to Pan ........................................ 100
Copying
and Pasting Text ............................... 102
Copying Text
into the Paste Buffer ...................... 102
Pasting Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Notes About Copying and Pasting Text. . . . . . . . . . . . . . . . . . . 104
8 Printers and Modems
Printers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Connecting a Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Selecting a Print Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Normal Mode: Printing Pages of Text . . . . . . . . . . . . . . . . . . . . 106
Auto Print Mode: Printing Text from the Host System. . . . . . . 107
Printer Controller Mode: Letting the Host Control Printing . . . 107
Local Controller Mode: Setting Up the Printer. . . . . . . . . . . . . 107
Assigning a Printer in 'I'w-o Sessions ....................... 108
Printer Set-Up Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Contents vii
Modems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . ... . . . . . . 111
Connecting to a Modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
9 VT420 Programming Summary
2 Character Encoding .................................. 113
3 Keyboard Codes
..................................... 120
4 Emulating VT Series Terminals. . . . . . . . . . . . . . . . . . . . . . . . . 122
5
Using Character Sets ................................. 122
6
Page Memory ....................................... 128
7 Visual
Character and Line Attributes . . . . . . . . . . . . . . . . . . . . . 129
8
Editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
9 Rectangular Area Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . 131
10 Cursor Movement- and Panning. . . . . . . . . . . . . . . . . . . . . . . . . 132
11 Keyboard, Printing, and Display Commands. . . . . . . . . . . . . . . 133
12 VT420
Reports ..................................... 136
13
Resetting and Testing the Terminal ..................... 142
14
Session Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
A VT52 Mode Control Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
10 Solving Problems and Getting Service
Operating Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Power-Up Self-Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Error Messages ....................................... 145
Digital
Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
On-Site Hardware Services ............................ 147
Off-Site Hardware Services ............................ 148
Software Service ...................................... 148
How to
Get Service .................................... 148

viii Contents
A Specifications
Site Planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . 150
Operating Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
LK401 Keyboard ...................................... 152
B Supplies and Docu mentation
Modems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Cables .............................................. 154
Related Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Ordering Information
.. ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
C Communication
Cables .............................................. 156
XONIXOFF Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Modem Connections
and Disconnections .................... 159
Break Function ....................................... 160
Connector Signals ..................................... 160
Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Glossary
Figures
1-1 VT420 Video Terminal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3-1 Set-Up Directory ........................... . . . . . . 25
6-1 Hexadecimal Compose Keys. . . . . . . . . . . . . . . . . . . . . . . . . 82
C-1 Cables......................................... 157
C-2 6-Pin Connector Pinouts ........................... 160

Contents ix
Tables
4-1 Keyboard Indicator Line Fields. . . . . . . . . . . . . . . . . . . . . . 46
4-2 Status Line Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5-1 Set-Up Directory Features. . . . . . . . . . . . . . . . . . . . . . . . . . 55
5-2 Global Set-Up Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5-3 Display Set-Up Features .... . . . . . . . . . . . . . . . . . . . . . . . 63
5-4 General Set-Up Features. . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5-5 Communications Set-Up Features . . . . . . . . . . . . . . . . . . . . 71
5-6 Keyboard Set-Up Features. . . . .. . . . . . . . . . . . . . . . . . . . . 74
5-7 Tab Set-Up Features .............................. 78
6-1 Key Sequences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
8-1 Printer Set-Up Features ........................... 109
9-1 Alias Primary DA Responses From the VT420. . . . . . . . . . . 140
9-2 ANSI Modes for DECRQM, DECRPM, SM, and RM . . . . . . 140
9-3 DEC Private Modes for DECRQM, DECRPM, SM, and RM. 141
9-4 Control Functions forDECRQSS Requests ............. 141
10-1 Common Operating Problems ....................... 145
10-2 Screen Error Messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
C-1 6-Pin DEC-423 Connector Interface Signals (Comm 1 or
Com.m 2) ....................................... 161

This guide provides the information you need to install, operate, and
maintain your VT420 video terminal. The guide describes the North
American version of the VT420 video terminal. A worldwide version is
also available.
The guide also provides a
summary of the control functions that
programmers can use when writing applications for the VT420 terminal.
For more detailed programming information, you can order the VT420
Programtner Reference
Manual from Digital. See Appendix B for ordering
information and a complete list of related documentation.
Organization
This guide has 10 chapters, 4 appendices, and a glossary. If you are
already familiar with video terminals, you may want to go immediately to
the installation section, Chapters 2 and 3.
NOTE
A handy summary of keyboard functions appears at the back of
the manual.
• Chapter 1, "A Look at the Terminal," gives you an overview of the
VT420 terminal and its features.
Installing Your VT420 Video Terminal
• Chapter 2, "Installation," shows you how to install your terminal and
connect it to a host computer system, terminal server, or modem.
Depending on·
your installation, you can use the terminal with two
computer systems at the same time.
xi

xii About This Guide
• Chapter 3, "Getting Started," describes how to set your terminal's
operating features to match your installation.
Using Your VT420 Video Terminal
• Chapter 4, "The Keyboard and Indicators," describes the terminal's
keyboard and explains the general function of each key. The chapter
also describes the terminal's indicators and status lines.
• Chapter 5, "Using Set-Up," describes how to use the VT420 set-up
screens. You use set-up screens to examine and change the settings of
operating features from the keyboard.
• Chapter 6, "Typing Additional Characters," describes how to select
characters that do not appear as standard characters on your
keyboard (such as accented letters).
• Chapter 7, "Using Two Sessions, Windows, and the Copy and Paste
Feature," describes how to use two sessions and windows on your
VT420. Depending on your installation, you can log into two computer
systems and view information from both systems at the same time.
• Chapter 8, "Printers and Modems," describes how to use a printer or
modem with your terminal.
• Chapter 9, "VT420 Programming Summary," is a summary of control
functions
that programmers can use with the VT420 terminal. The
chapter shows the· character sets that are built into the terminal.
• Chapter 10, "Solving Problems and Getting Service," provides
suggested solutions for typical
operating problems and tells you
where to get more help.
Appendices
• Appendix A lists VT420 specifications.
• Appendix B provides ordering information for supplies and
documentation.
• Appendix C provides detailed information on communication with a
host computer system, including cables and connector signals.

About This Guide xiii
Conventions
The following conventions are used in this manual:
Cautions
Notes
Set-up features
Keyboard keys
Glossary entries
Provide information to prevent damage to equipment.
Provide general operating infonnation.
The names of features appear in bold type.
Example: Use the save feature in the Set-Up
Directory screen.
Set-up feature settings and fields appear in this type.
Example: The cursor is on the Global field in the
Set-Up Directory.
Appear in a Ibox I.
Example: Press the IReturn Ikey.
For ICtr11 key sequences, hold down ICtr11 and press the
other key.
Appear in italics when first used in text.
Example: The VT420 stores information in its page
memory.

This chapter introduces you to the VT420 video display terminal. The
VT420 is a general-purpose terminal that you use to communicate with a
host computer system. The chapter provides an overview of the terminal
and its basic operating features. The chapter also tells you where to look
in this guide for more iuformation about each feature.
VT420 Components
The VT420 has two main components, a monitor/terminal unit and a
keyboard (Figure
1-1). The monitor/terminal unit is simply called the
terminal in the rest of this guide.
Terminal
The VT420 uses a 359 mm (14 inch) monochrome screen. The VT420
screen can display 24, 25, 36, or 48 lines of text in 80 or 132 columns.
There are two connectors on the rear of the terminal, for connecting the
VT420 to one or two host computer systems. You can also use one of
the connectors to connect to a printer. Chapters 2 and 3 describe the
terminal's connectors.
The terminal's tilt and swivel base lets you adjust the screen to the
viewing angle you prefer.
1

2 A Look at the Terminal
Keyboard
The VT420 uses Digital's LK401 keyboard. The keyboard has four groups
of keys and two indicator lights. The main keypad looks similar to a
typewriter keypad. A cable connects
the keyboard to the right side of the
terminal.
Chapter 4 describes the LK401 keyboard.
Figure 1-1 VT420 Video Terminal

A Look at the Term inal 3
Your Computer System
You can use the VT420 with one or more computer systems. You have
several options for connecting your terminal to a computer. You can
connect the VT420 directly to acorn puter, or indirectly through a terminal
server
or modem. The system you connect to is called the host.
Nonnally, the keys you type on your keyboard send information to the
host. The host stores the information and displays it on the terminal's
screen. You can print the data by sending it to a printer connected to the
terminal.
You can use the VT420 with the application software on your host. For
example, your host may have applications that let you do word processing,
data entry, or programming.
Features
With a VT420, you can
• Select operating features from the keyboard.
• Use two computer sessions on one terminal.
• Display information from two sessions at the same time. You can
select two windows from the keyboard.
• Copy information from one session to another session.
• Display 24, 25, 36, or 48 lines of text in 80 or 132 columns.
• Store d~ta locally in page memory for display.
• Store frequently used commands and text in macros.
• Fill the screen with a dark or light background for viewing comfort.
• Align the screen.
• Check the terminal's operating status.
Set-Up
Set-up is a series of display screens that let you examine and change
the terminal's operating features from the keyboard. Each screen lists a
particular set of operating features for the terminal. For example, one
set-up screen lists communication features, while another lists keyboard
features.

4 A Look at the Terminal
Some features are for your convenience, and some are required by your
host computer system. Each set-up feature has a factory-default setting.
You
ca~ select the settings that are right for your system.
Chapter 5 describes set-up in detail.
Two SeSSions
When you use the terminal to communicate with a computer system, you
have established a session on that system. The VT420 lets you establish
two sessions and display data from both sessions at the same time. You
can connect the terminal to two different systems, depending on your
installation (Chap~er 2).
Here are some important tools you use to select and run two sessions:
Terminal comm ports set-up feature
SSU Enable command
Windows
~ (Session) key .
The procedure for selecting and running two sessions is simple. Here are
the basic steps:
1. Set the terminal comm ports feature to match your cable
connections to
the host system.
2. Use
the ~ key or the SSU Enable command to initiate two sessions.
3. Press the ICtr11 ~ keys to select two windows.
4. Use
~ to easily switch back and forth between two sessions.
Chapter 3 provides the detailed procedures for setting up your tenninal to
run two sessions. Chapter 7 describes how to use two sessions.
Windows
You can divide your screen into two windows. With windows, you can see
information from two sessions at the same time. There are two styles of
windows, full screen and split screen. The default is a full-screen window.
To change the window style, you simply press the ICtrlj ~ key combination.
When you divide the screen into two windows, you can adjust their
relative size by moving the border between them up or down. Chapter 7
describes
how to use windows.

A Look at the Terminal 5
Number of Lines on the Screen
The VT420 lets you select a font size to display 24, 36, or 48 lines on the
screen. You use the lines/screen feature to select the number of display
lines. Chapter 7 describes how to select the number of lines/screen.
Page Memory
The VT420 has off-screen memory to store data entered from the keyboard
or host system. The VT420 can store 144 lines of text.
The terminal's memory is called page memory, because you can divide the
144 lines into a different number of pages. By default, the terminal uses
6 pages of 24 lines each. If you run two sessions, the default format for
each session is 3 pages of 24 lines.
Pages create boundaries that affect the way the VT420 displays text.
To take advantage of page memory, your applications must be able to
recognize
these page boundaries.
See the page arrangement feature in the "Display Set-Up Screen"
section of Chapter 5.
Copy and Paste
The VT420 has a copy and paste feature that lets you copy information
displayed on the screen and send it to the host system. You can send the
copied text to the same session or to another session.
Chapter 7 describes how to copy and paste text.
Status Line
The VT420 displays a status line at the bottom of the screen. If you are
running two sessions, the terminal displays a separate status line at the
bottom of each session. The status line has several fields that provide
information about the terminal's operating status. For example, one field
shows
you the current position of the cursor as a set of screen coordinates
(row and column number). Applications may also use the status line to
send you messages.
Chapter 4 describes the status line.