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CHAPTER 1
INTRODUCTION TO EDT
1.1 OVERVIEW
EDT is an interactive text editor available on five DIGITAL operating
systems: TOPS-20, VAX/VMS, RSTS/E, RSX-11M, and RSX-11M-PLUS. You
can use EDT with most kinds of text files -- letters, memos, or
complex computer programs. With EDT you can create files, insert text
into them, and edit and manipulate that text. You can also edit and
manipulate text in existing files. This manual describes EDT for the
TOPS-20 operating system.
EDT has a number of features to assist you in your editing work:
o Three types of editing: keypad, line, and nokeypad. You can
move from one mode to another during the same editing
session.
o An online HELP facility. You can use this any time during
your editing session without affecting your work.
o A journal facility. The journal file protects your editing
work in case of a system interruption.
o to files and buffers. You can work with as many files and
buffers as you need during your EDT session.
o Startup command files. These enable you to preset and
customize the characteristics of your editing sessions.
o The key definition facility. You can create additional
keypad editing functions to customize your editing work and
extend the capabilities of keypad editing.
o EDT macros. You can use EDT macros to customize your editing
work and extend the capabilities of line editing as well as
keypad and nokeypad editing. Macros can be saved for use in
later editing sessions.
o The tabbing facility. This feature enables you to create
layered text formats.
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INTRODUCTION TO EDT
EDT has two screen modes: keypad and nokeypad. You can use these
modes on VT100 type and VT52 terminals. Check Appendix C to find out
if the screen modes are supported on your terminal. Although both
screen modes can perform the same functions, keypad editing has
greater flexibility than nokeypad mode. However, with a good
understanding of nokeypad commands, you can extend the capabilities of
keypad mode by creating definitions for additional function keys
definitions. Keypad editing is described in Chapter 3, nokeypad
editing in Chapter 5.
If your terminal cannot accommodate screen mode, you will be using
line mode, which is described in Chapter 4. Screen mode users will
find some line mode commands useful, particularly those that access
other files and buffers during your editing session.
1.2 AN OVERVIEW OF THE EDT EDITING SESSION
To use EDT, you must type a system command that calls up the EDT
Editor and tells it the name of the file you want to edit or create.
EDT starts, by default, in line mode. As soon as you see line mode's
prompt character, the asterisk (*), you are ready to begin editing.
If you have a VT100 type or VT52 terminal, you can shift to screen
mode to do your editing work. To shift to keypad mode, type the line
mode CHANGE command. (To shift to nokeypad mode, you first type the
SET NOKEYPAD command and then the CHANGE command.)
From this point on, your work can include adding and deleting text,
correcting mistakes, moving text around in a variety of ways, or
locating pieces of text.
When you finish your work, you have the choice of saving the new
version of your work or eliminating all record of your editing
session. If you want to save your work, EDT copies the text you were
editing to an external file. If not, EDT simply erases all trace of
the editing session.
1.3 TYPES OF EDT COMMANDS
EDT commands can be divided into three main groups and one subgroup.
The main divisions are keypad, line, and nokeypad. Although the SET
and SHOW commands are line mode commands, they are considered a
special subgroup since they can affect how EDT operates in all three
modes. Keypad commands are generally called keypad functions to
emphasize that you do not type letters to tell EDT to perform an
operation, but instead press the key or keys that have been assigned a
particular editing function.
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INTRODUCTION TO EDT
1.3.1 Keypad Editing Functions
In keypad editing, you press keypad or keyboard keys to tell EDT which
editing function to perform. The position of the cursor on the screen
tells EDT where to begin performing the operation. When you start
using keypad mode, you will rely on the preset function keys. Later
on, you can create your own definitions for EDT function keys.
1.3.2 Line Editing Commands
Line editing commands consist of English words that you type in
response to EDT's asterisk prompt (*). In addition to command words,
there are qualifiers and specifiers that determine how the commands
are processed and the extent of the operation. The major specifier --
range -- tells EDT which line(s) you want the command to affect. Line
mode commands use the physical text line as the basis for operation.
Text manipulations are performed on a single line or group of lines.
Line mode commands enable you to move text to and from external files,
as well as from one place to another within the various locations set
up in your EDT session.
1.3.3 Nokeypad Editing Commands
Nokeypad commands, like line mode commands, consist of English words
and abbreviations. Some commands also take specifiers. The main
specifier in this mode is "entity," which tells EDT what portion of
the text to process.
Nokeypad commands perform the same operations as keypad functions, but
there are more entities and commands available in nokeypad editing.
By defining your own keypad function keys, you can take advantage of
these additional capabilities when you edit text in keypad mode.
1.3.4 The SET And SHOW Commands
SET commands are line mode commands that set a variety of operating
elements for your EDT session. These commands have no effect on the
text you are editing; rather, they modify the way EDT behaves. For
example, you can use SET commands to change the way EDT performs
searches or to reduce the amount of text that EDT displays on your
screen.
SHOW commands are line mode commands that tell you the status of
various elements of your editing session. Each SET command has a
corresponding SHOW command to tell you which setting is in effect.
Additional SHOW commands tell you which buffers currently exist in
your session, your input and output file specifications, the
definitions of keypad function keys, and the EDT version you are
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INTRODUCTION TO EDT
currently using.
1.4 SPECIAL FEATURES
EDT's special features include online HELP information and the
recovery system. You can use the key definition and macro facilities
to extend EDT's capabilities. Other facilities include startup
command files and formatting using the tab commands.
1.4.1 The HELP Facility
EDT's online HELP facility allows you to get help during your editing
session without discontinuing your work. In keypad mode you can get
information on key functions by pressing the HELP keypad key and then
the function key you want to know about. For information on line and
nokeypad commands, you use line mode's HELP command. Details on using
the HELP facility are given in the chapters for each mode: Chapter 3
for keypad, Chapter 4 for line, and Chapter 5 for nokeypad. In line
mode you can use EDT's command recognition features to assist you.
These are also described in Chapter 4.
1.4.2 The Journal Facility
EDT's journal facility enables you to recover your EDT session if it
is interrupted due to a problem at the system level. EDT saves a file
containing all your editing commands whenever an unexpected
interruption to your work occurs. You can have EDT process this
journal file to restore your work to the state it was in before the
interruption. Chapter 2 tells about the journal facility and shows
how to use it.
1.4.3 Startup Command Files
With startup command files you can preset various elements of your EDT
session. These special files consist of line mode commands. The
commands that most frequently appear in a startup command file are SET
and DEFINE KEY. EDT automatically processes all the commands in the
file as soon as you type the system command to start editing your
text. Details on startup command files appear in Chapter 7.
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INTRODUCTION TO EDT
1.4.4 Key Definitions For Keypad Function Keys
You can add to the preset keypad function keys by creating your own
definitions for keypad keys or keyboard key sequences. Key
definitions are based on nokeypad commands. You can combine several
commands into one key definition. Chapter 7 contains information on
how to define keys as well as some applications that use defined keys.
1.4.5 Macros
You can add to the list of preset line mode commands by creating
macros. Macros are groups of line mode commands that function as a
single line mode operation. The macro name becomes an EDT line mode
command for the remainder of your session. When you type the macro
name, EDT performs the operations included in that macro. You can use
macros to change SET commands or process a group of DEFINE KEY
commands. Macros are explained in Chapter 7.
1.4.6 Tabbing
EDT has several commands that perform tabbing operations in the screen
modes and one tabbing command for line mode. These commands enable
you to indent lines to format text such as outlines and indented
computer programs. See Chapter 7 for an explanation of the tabbing
facility.
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