Editing Time Sharing Option (section)

== Use ==
In computing, [[time-sharing]] is a design technique that allows many people to use a computer system concurrently and independently—without interfering with each other.<ref>{{cite web |title=Time-sharing |url=https://www.britannica.com/technology/time-sharing |website=Britannica.com |publisher=Encyclopaedia Britannica |access-date=20 December 2020}}</ref> Each TSO user is isolated; it appears to each one that they are the only user of the system.{{efn|However, users can, e.g., send each other messages.}}

TSO is most commonly used by mainframe [[system administrator]]s and programmers. It provides:
* A [[text editor]]<ref>{{Cite web|url=https://www.ibm.com/docs/en/zos/2.5.0?topic=subcommands-edit-command|title=EDIT command - z/OS 2.5.0 - TSO/E Command Reference|website=ibm.com}}</ref>
* [[Batch job]] support, including completion notification
* [[Debugger]]s for some programming languages used on [[System/360]] and later IBM mainframes
* Support for other vendors' end-user applications, for example for querying [[Information Management System|IMS]] and [[IBM DB2|DB2]] [[databases]]

TSO interacts with users in either a line-by-line mode or in a full screen, menu-driven mode. In the line-by-line mode, the user enters commands by typing them in at the keyboard; in turn, the system interprets the commands, and then displays responses on the terminal screen. But most mainframe interaction is actually via [[ISPF]], which allows for customized menu-driven interaction. This combination is called ''TSO/ISPF''. TSO can also provide a Unix-style environment on OS/390 and z/OS via the [[UNIX System Services]] [[Unix shell|command shell]], with or without ISPF.

TSO commands can be embedded in [[REXX]] and [[Object REXX|ooRexx]] execs or [[CLIST]]s, which can run interactively or in batch.

TSO eliminated the need to punch cards on a [[keypunch]] machine, and send [[punched card|card]] decks to the computer room to be read by a [[Punched card input/output|card reading]] machine.