EDT is a character-based

text editor A text editor is a type of computer program that edits plain text. An example of such program is "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be used to c ...

from

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until ...

(DEC) running on

PDP-11 The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...

(

RSX-11 RSX-11 is a discontinued family of multi-user real-time operating systems for PDP-11 computers created by Digital Equipment Corporation. In widespread use through the late 1970s and early 1980s, RSX-11 was influential in the development of later ...

RSTS/E RSTS () is a multi-user time-sharing operating system developed by Digital Equipment Corporation (DEC, now part of Hewlett-Packard) for the PDP-11 series of 16-bit minicomputers. The first version of RSTS (RSTS-11, #Versions, Version 1) was implem ...

and

RT-11 RT-11 (Real-time 11) is a discontinued small, low-end, single-user real-time operating system for the full line of Digital Equipment Corporation PDP-11 16-bit computers. RT-11 was first implemented in 1970. It was widely used for real-time compu ...

), and later for its

OpenVMS OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers using Op ...

operating system. It can respond to single keystrokes, and uses

function key A function key is a key on a computer or computer terminal, terminal computer keyboard, keyboard that can be programmed to cause the operating system or an application program to perform certain actions, a form of soft key. On some keyboards/com ...

s to implement commands to the editor. EDT was introduced originally as a line-mode editor. The screen mode was developed first as the Keyboard Editor (KED) on RT-11 as part of the FMS-11 project by Darrell Duffy; EDT on the other operating systems was then enhanced to be compatible with KED. The editor contains both line mode commands and a screen based editor. In screen mode, the default action for the user is to directly update text as they type, with special commands available by pressing keypad commands. Arrow keys allow for simple navigation, while keypad commands allow for more complex navigation and searches. As with many user interfaces developed around this time, EDT uses the " Gold Key" style of input first developed for the

WPS-8 WPS-8 is a Word Processing System sold by Digital Equipment Corporation for use with their PDP-8 processors (including the VT78, VT278 DECmate, and PC238 DECmate II and PC24P DECmate III microcomputer systems). WPS-8 supports a variety of 24 ro ...

word processing system. "Gold Key" editing uses the PF1 keypad key as a prefix key allowing the introduction of a wide variety of commands using both the keypad keys and keys on the main keyboard. Pressing the PF2 keypad key gives on-screen help on the keypad and other key combinations: /-----------------------------------\ /-----------------------------------\ , ^ , DOWN , , , , , , FNDNXT , DEL L , , , , , , <---- , ----> , , GOLD , HELP , , , , , , , , LEFT , RIGHT , , , , FIND , UND L , , UP , v , , , , --------+--------+--------+--------, \-----------------------------------/ , PAGE , SECT , APPEND , DEL W , DELETE Delete character , , , , , LINEFEED Delete to beginning of word , COMMAND, FILL , REPLACE, UND W , BACKSPACE Backup to beginning of line , --------+--------+--------+--------, CTRL/A Compute tab level , ADVANCE, BACKUP , CUT , DEL C , CTRL/D Decrease tab level , , , , , CTRL/E Increase tab level , BOTTOM , TOP , PASTE , UND C , CTRL/K Define key , --------+--------+--------+--------, CTRL/R Refresh screen , WORD , EOL , CHAR , , CTRL/T Adjust tabs , , , , ENTER , CTRL/U Delete to beginning of line , CHNGCASE, DEL EOL, SPECINS, , CTRL/W Refresh screen , -----------------+--------, , CTRL/Z Exit to line mode , LINE , SELECT , , , , , SUBS , Press a key for help on that key. , OPEN LINE , RESET , , To exit, press the spacebar. \-----------------------------------/ Users can configure default actions or define key sequences for their editor by placing EDT commands in an initialization file which is executed upon starting the editor. DEC later developed TPU, a powerful language for designing text editors on its VMS systems. TPU was used to produce a new standard text editor,

EVE Eve is a figure in the Book of Genesis in the Hebrew Bible. According to the origin story, "Creation myths are symbolic stories describing how the universe and its inhabitants came to be. Creation myths develop through oral traditions and there ...

, as well as to rewrite EDT. EVE included an emulator of the EDT screen mode keypad for the benefit of those who were used to particular key functions. Both EVE and the TPU implementation of EDT are still distributed with

. Text editors based on the EDT user interface have been developed for other systems, including for instance sedt, an EDT-based editor for

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

systems.

References

{{Reflist

External links

A clone of Digital EDTRush Record/Charles Sandmann's portable Digital EDT clone
OpenVMS text editors