TECO (text editor)

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TECO (originally T ape E ditor and CO rrector , later T ext E ditor and CO rrector ) is a text editor for computers from DEC . TECO was developed in 1962/63 by Daniel L. Murphy for the PDP-1 at MIT . Originally, TECO was used to process punched tapes.

TECO versions were available for all PDP computers, and TECO could also be used on the VAX under VMS thanks to the existing PDP-11 emulation. TECO is still part of the current OpenVMS version distributed by Hewlett Packard Enterprise .

Working with TECO is very cryptic, as it was optimized to control the editor with as few keystrokes as possible or to create powerful macros . As the name suggests, a large number of TECO commands are derived from common work steps at a time when programming was still practiced with the help of scissors, adhesive tape and punch cards .

TECO is the predecessor of Emacs , which was initially a collection of TECO macros that made it possible to edit texts in a full-screen mode with an immediate view of the changes. From 1986 there was such a graphic version of TECO itself with Video TECO; this mode was also found in later imitations by TECO.

TECO as a programming language

With its macro functions, TECO is a complete programming language. Alan Kotok wrote a Lisp interpreter in TECO during his studies . An essential element for the programming function are the Q registers , 36 memories (named 0–9 and A – Z) that can hold both text and numerical values. If a Q register contains text, this text can be further processed, output or - if it is a valid TECO command sequence - also executed. It is therefore possible in TECO to first generate program parts during the run and then to execute them.

A trivial example of a TECO program (summation of the numbers from 1 to 100) is 0uA0uB100 <% A + qBuB $> qB = $$ . The $ character that occurs here is the TECO representation of the Escape key , so you have to Escenter it here; Escseparates commands (if necessary) and terminates text input, EscEscexecutes the command chain.

Modern implementations

TECO can still run today on the various simulated PDP computers that are available for simulating historical computers as part of the SIMH project . There are also later implementations for various other operating systems, including Microsoft Windows , Linux, and macOS .

Individual evidence

  1. Daniel L. Murphy's homepage (English)
  2. TECO in the HP OpenVMS system documentation ( Memento of the original from June 13, 2011 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed December 18, 2009 @1@ 2Template: Webachiv / IABot / h71000.www7.hp.com
  3. TECO Manual V4. Retrieved October 8, 2018 .
  4. Tom Almy: Overview page about different TECO versions. Retrieved October 8, 2018 .