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The History of the "Undo" Function? 61

TheLocustNMI asks: "So, earlier today as I was typing out some magnum opus of a stored procedure, I highlighted to copy it, and hit SPACE instead of Ctrl-C. Without thinking, I hit Ctrl-Z to 'undo' my folly. Pausing a moment to reflect, I realized that I own countless hours of thanks to whomever came up with the "undo" button. In short -- my question is this -- where did it come from? What are the earliest implementations of the 'undo'? (a quick googling returns this page, a cornucopia of undo and history related treatises)"
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The History of the "Undo" Function?

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  • My guess would be that it's been around since the late '60s, if not earlier. It's something so useful, and so easy to implement, that I would be suprised if it hasn't been around at least that long.
    • It's not easy to implement. It's actually a lot of work. Suppose, for example, you're building a 3D animation system and every operation needs to be undoable. Every time you tweak a vertex, or intersect two polyhedra, or retesselate a primitive you need to have a way of undoing it. This isn't just a few lines of code. It means that every time you write some code to do anything you need to write code to undo it. This is a lot of work.
      • Well obviously the more complex the work the more complex the undo function. But nobody did 3D animation in the '60s. For simple text editing, it would be easy to implement, provided you had enough RAM to store duplicates of portions of the text.
  • by LowellPorter ( 466257 ) on Tuesday January 07, 2003 @11:33PM (#5037808) Journal
    The "undo" button before computers was white-out. You could never have enough of that stuff around. Especially if you were from a family like mine with several kids doing term papers.
  • by Anonymous Coward on Tuesday January 07, 2003 @11:39PM (#5037831)
    A better place to ask this question would be alt.folklore.computers on usenet.
  • by Picass0 ( 147474 ) on Tuesday January 07, 2003 @11:48PM (#5037874) Homepage Journal

    Seeing how things have been lately, it's worth finding an answer for this question before someone attempts to patent the idea.
  • Arabian Nights? (Score:3, Interesting)

    by MarkusQ ( 450076 ) on Wednesday January 08, 2003 @12:14AM (#5037960) Journal

    IIRC, there was an example in the Arabian Nights. Of course, this was long before computers but it still worked like magic.

    -- MarkusQ

    P.S. On a more serious note, I wouldn't be all that shocked to learn that 'undo' wasn't implemented on a computer before the 1970s. My main reason for thinking that is that it is relatively expensive, and really only useful in interactive environments. When you're editing your program by manually shuffling h-cards, there isn't much sense in having "undo".

  • by hari ( 15720 ) on Wednesday January 08, 2003 @12:55AM (#5038095) Homepage
    .. or do you find yourself saying "Control-Z" in your mind whenever you find yourself making mistakes while not sitting in front of a computer..spilling a glass of milk...etc

    • Not really, but I do find myself calling the apostrophe "rem" from my BASIC days. Yeesh.
      10 ' Hello world program
      20 ? "Hello World."
      Of course, things went different with the Commodore ...
      10 rem Hello world program
      20 pR "Hello World."
      But only if you had the Caps-Lock off.

      Wee ... Offtopic +1!

      • Of course, things went different with the Commodore ...

        10 rem Hello world program
        20 pR "Hello World."

        Hmmm...IIRC, line 20 would cause an error. I think that pR would translate to "print#", which required a channel number before the string. The abbreviation for "print" was still "?".
    • .. or do you find yourself saying "Control-Z" in your mind whenever you find yourself making mistakes

      Actually, Control-Z brings to mind the old DOS EOF character.

      The proper "undo" is either "u" or Control-Shift-_, depending on if you're a vi or emacs person.

      • Control-Z brings to mind the old DOS EOF character. The proper "undo" is either "u" or Control-Shift-_

        What about Command+Z, the Mac OS undo keystroke that Microsoft shamelessly copied into Ctrl+Z in the Windows OS?

    • .. or do you find yourself saying "Control-Z" in your mind whenever you find yourself making mistakes

      No, just when I'm getting ready to go to bed.
  • by tdelaney ( 458893 ) on Wednesday January 08, 2003 @01:09AM (#5038156)
    That's right people ... Apple did it first (at least in a consumer machine).

    The original Macintosh had "undo" functionality in its applications, right from the start.

    The Apple IIGS also had "undo" functionality.

    There may have been one or two individual applications before it (I don't know) but the Mac made "undo" ubiquitous.
    • by tdelaney ( 458893 ) on Wednesday January 08, 2003 @01:11AM (#5038163)
      Although, IIRC there wasn't originally a command key associated with it ... you had to go to the menu.

      "Command-Z" was chosen to match with the existing command keys of "Command-V" (paste), "Command-C" (copy) and "Command-X" (cut). All the major editing command keys were in the one location.
      • Hmm, I'm pretty sure it was always Command-Z, no mousing required, but it was before it was called the Command key. It was just that key with the weird symbol on it (personally I called it "funnykey" back in the mid-80s). The Jargon file lists it under "feature key [tuxedo.org]".

        I know on the IIgs and some Mac keyboards it was the same as the open-Apple key (I forget what the closed-Apple key was used for). On the original mac, though, I think it just had the symbol. A google search [google.com] on Apple's site turns up a number of images of keyboards among other things, though not one of the original Mac.

        So the question left is, was there a documented implementation of Undo on a computer before the original Mac? Perhaps in some old word processing programs? I know there were some I used on the Apple II, but I certainly can't remember what functions they had after 20-some-odd years.

        • by js7a ( 579872 ) <james@bov i k . o rg> on Wednesday January 08, 2003 @03:29AM (#5038548) Homepage Journal
          was there a documented implementation of Undo on a computer before the original Mac?

          Yes, MIT's Lincoln Reckoner [google.com] had multiple-level undo/redo in 1968. That used a screen editor, so it would be the kind of undo you are talking about, however it was probably inspired by IBM's APL line-based workspace editor.

          APL programmers had multiple-level undo/redo on their selectric typewriters around 1965. Each interaction was numbered, and you could select the number of the last interaction you wanted to keep. This would reset the entire workspace so that all variables, your program image, and options would be restored. This worked by saving the workspace each time a command completed, and was also useful for restoring sessions after interrupted connections.

          Single-level undo appeared much earlier -- the first IBM teletype line editors in the late 1950s had single-level undo.

          • How was the multi-level undo navigated/discovered? Was it sequential and blind (hit undo, see what you get) or was it random-access (like the History panel in Photoshop). Adobe probably has a patent on the History panel anyhow...
            • I guess Lincoln Reckoner was like EMACS is: you hit undo, and look to see what you got. I don't know what the granularity for undo of inserts was -- probably character-by-character or all-at-once.
      • Which is incredibly more convinient if you do not use a German keyboard, where z and y are switched. *sigh*
        I never saw this mentioned in the usability reports I read.
        • ... where the Z is located, well, I guess you can figure it out.
          • This would wo Ctrl+W... that'll be better :)
            To what language does AZERTY belong?
            • AZERTY is used in France and Belgium; in France and the soutern part of Belgium it's used with French, in the northern part of Belgium it's used with Dutch.

              The stupid thing is, there is even a difference between French azerty and Belgian azerty. All the letters are in the same place, but there are difference with regards to other characters like the backslash.

              BTW, not everyone uses azerty around here. Some folks, especially programmer types, use qwerty.

    • This is also the first place I remember it. But, was it Mac Write, or Word that had it first?

      Also, I'm sure someone will tell how Steve stole it from Xerox, IBM, Santa Clause, or the Tooth Fairy.

      I always wondered why it was Command-Z. Thanks for clearing that up.
    • The Brief DOS-based programmer's text editor in had a fine undo. Don't know whether this dates to before the Mac or not--perhaps not. You could select how many undos are possible in a row.
  • So, earlier today as I was typing out some magnum opus of an e-mail message in Outlook, I highlighted to copy it, and hit SPACE instead of Ctrl-C. Without thinking, I hit Ctrl-Z twice to 'undo' my folly. While the spaced-over text reappeared with the first Ctrl-Z, it disappeared again with the second Ctrl-Z. My typing was now undone forever, leaving me with a blank message. Pausing a moment to reflect, I realized that whoever came up with the "undo" button without providing a "redo" button only did a half-hearted job.

    btw, the "Done buns can't be undone" saying from Insomnia keeps on playing in my head...
  • by BornInASmallTown ( 235371 ) on Wednesday January 08, 2003 @10:00AM (#5039756)
    I use a graphical programming language from National Instruments [ni.com] called LabVIEW [ni.com]. It did not have the undo feature for over 10 years since its introduction, and I will never forget the sinking feeling of hitting the Delete key on accident only to see a whole page of graphical code lost forever!


    NI added undo to LabVIEW in the 5.0 release (ca. 1997) of the product. It was really funny how the marketing from NI revolved around that feature. "Now with UNDO!" You would think that promoting the introduction of a feature that is so ubiquitous in most other desktop software would be less than effective--that people would groan because they had expected it for so long. However, at one of their trade shows, the presenter mentioned the new UNDO and got a standing ovation.

  • Don't, things are sure to 'break' if you hit Ctrl+C.
  • The Xerox Alto system I first used around 1980 (and it wasn't new that year) had an undo function that worked in every program and could take you all the way back to the beginning of your session. If I remember you could have it work contiuously somehow, and it would undo all your work before your eyes.

    BTW, the system was also a WYSIWYG high res windowed display, with three button mouse, laser printer, removable (personal) hard drive, drag and drop file handling, ethernet with an internet (arpanet, actually) connection. The first thing I ever saw on it was someone in Rochester, NY playing a 3-D real-time multiplayer game (mazewars?) with someone in California.

    I have never quite recovered from the IBM PC downgrade.
    • Interlisp in all its incarnations had a module called DWIM (Do What I Mean) which caught typos and thinkos in your input and offered to correct them for you. It was at its smartest fixing spelling errors and inserting parentheses (it would guess '(foo)' when you typed 9foo0, for example).

      DWIM could be turned off, set so it asked you before changing anything, or set to automatically fix your inputs. That last setting would be completely intolerable without UNDO, which Interlisp also had, so even if DWIM guessed wrong, corrected your input to the moral equivalent of 'rm *', and ran it, you could still recover with UNDO and try again.

      The oldest Interlisp reference I can find is the 1978 Interlisp reference manual. Lisp was on Altos as early as 1973, hacked up by L. Peter Deutsch. For an academic take on UNDO, see this paper [nec.com] from ACM TOPLAS (courtesy of Citeseer).
  • You ever tried to pick up chicks by elaborating on the history of the undo command in a dark bar?

    Let me know how it works out.

  • The Atari ST series certainly weren't the first to support undo in applications, but they did have a dedicated "Undo" key (as well as a dedicated "Help" key). Far more useful to a new user than Ctrl-Z or F1 yet something that is still missing, even from most of the current range of expanded keyboards.
  • The Interlisp Editor [trailing-edge.com] had an "Undo" function in 1975. See the directory listing here [trailing-edge.com].
  • "Commit" = "Undo" (Score:4, Interesting)

    by dpbsmith ( 263124 ) on Wednesday January 08, 2003 @08:52PM (#5044285) Homepage
    I remember a rudimentary CAD program for the Apple ][+, circa 1982 or 1983. I wish I could remember the name...

    I personally first encountered "Undo" on the Mac in 1984. But this CAD program had a function... they didn't call it "commit." I don't remember the exact language they DID use.

    The idea was that you never had to worry about making mistakes, because every action you took was tentative, and would be shown to you as a preview before taking effect.

    So you'd give a command to draw a line, you'd see the line onscreen, and you could either accept it (in which case it became part of the drawing) or reject it (in which case it disappeared).

    The weird thing about all this is that logically, it is exactly equivalent to an "undo" function.

    And the even weirder thing is that while an "undo" function feels empowering and liberating... when the exact same function was presented as "tentative action, preview, accept/reject" it felt clumsy and laborious.

    To me, anyway.
    • I imagine it felt worse because you had to make sure you wanted to commit - the default action would presumably be to not commit (if you don't do anything), whereas with undo, you act as if what you have is correct, and only do something extra if you catch an error.

      Disclaimer: I've never used that program

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