Talk:Undo

History of Undo
Anyone have any idea of when undo was first implemented and how Ctrl-Z became associated with the command?


 * It comes from the Macintosh, possibly the Lisa. The Edit menu was laid out in a standardized fashion with Undo, Cut, Copy, Paste and Clear (Delete) the command key equivalents were assigned to be the bottom left four keys on the keyboard (Z, X, C, V) and the backspace for delete. These keys are nearest to the modifier (command) key used to invoke them and so were presumably chosen to be easily reachable for these very common operations. The X for Cut and the C for Copy also have the benefit of being somewhat mnemonic.58.168.23.95 (talk) 14:26, 8 April 2008 (UTC)


 * Undo definitely predates the Mac. It was on the AtariWriter program for example in, I think, 1981-- and was not new then. But those key sequences could well do, though they may have been present on the Xerox Parc machines, I don't know. SimonTrew (talk) 13:08, 30 April 2009 (UTC)


 * It now appears to be in the article. Certainly the Xerox Parc work influenced the Lisa/Mac work. But I think it was the Mac that, through the necessity of scarce resources and thus requirement to use the standard Toolbox, made Undo universal across all applications on the platform. All the Apple software (MacWrite, MacPaint, etc) and Microsoft software (Word, later Excel, etc) as well as the personal databases and later music and video editors all universally supported it, tied to the same key combo. --Sam (talk) 13:38, 3 March 2018 (UTC)

Discussion on ctrl-z and other ctrl- commands
I needed the redo command and had to research ctrl-y to add it to the undo article. Anyone have a complete list of ctrl-? commands (ctrl-c, ctrl-v, ctrl-x, ctrl-y, ctrl-z, etc.) and would be interested in creating a page baised on them? (Sorry, Warren S. Black blackjnk@yahoo.com - haven't taken the time to create an account here, yet. ;) —Preceding unsigned comment added by 71.219.143.182 (talk) 07:59, 29 February 2008 (UTC)

Wikipedia itself
Do article edits have an undo function? Can this be explained in this article? BrainyBabe 14:20, 13 February 2007 (UTC)
 * Reverting article edits is explained at Help:Page history. I would not add this to this article as I would want to avoid mixing namespaces. &mdash; Tobias Bergemann 15:33, 13 February 2007 (UTC)
 * Thanks for explaining.BrainyBabe 16:40, 13 February 2007 (UTC)
 * Shouldn't there be italic font at the top of the page saying something like "for the wikipedia feature see Wikipedia:Undo? Please reply to MY talk page because this page isn't on my watchlist. TheBlazikenMaster 12:35, 28 March 2007 (UTC)

Undo Models
"Non-linear undo can be further subcategorized into direct selective undo vs. script interpretation undo vs. cascading undo." That's nice. What are those then? The page makes no mention. I'm guessing that a "cascading undo" also undoes any subsequent actions that have the explicitly undone action as a prerequisite...

Warren Teitelman should be credited
Warren Teitelman had already written about undo and had implemented it before 1976

https://saltworks.stanford.edu/assets/mb938wh0570.pdf — Preceding unsigned comment added by Edw2323 (talk • contribs) 00:35, 22 February 2014 (UTC)

Emacs
Emacs certainly did multi-level undo before 1980. And likely it was based on earlier software (teco?). Also Emacs has an unusual multi-level model where there is no different Redo command. Instead Undos are actually actions added to the undo stack, and any non-undo action would move the undo pointer back to the end of the stack. So undo,undo,'x',undo,undo,undo would do 2 undos, then insert an 'x', then undo the insertion, and then 'redo' both the first undos.Spitzak (talk) 20:49, 26 January 2018 (UTC)