When was the undo invented?
October 6, 2006 9:33 AM   Subscribe

When was the undo invented? Is it a computer thing, or did a mechanical undo exist before that?
posted by lorbus to Computers & Internet (16 answers total)
 
Well, before computers, it wasn't really an "undo." It was called "using the eraser," or "white-out," or something like that. Or am I missing something?
posted by danb at 9:36 AM on October 6, 2006


I was going to say what danb said. This is an interesting question but you need to clarify it. By "undo" do you mean an operation which brings back the system to a previous state?

In that case would the "previous channel" button on TV remote controls count?
posted by vacapinta at 9:39 AM on October 6, 2006


Some of the earliest "programmable" devices were directed by ropes passing through a series of gears with various cam systems to create changes in direction, etc. I don't think the "undo" model we know of now fits well into this linear scale, although winding the rope back up was the only way to "reset" them.
posted by prostyle at 9:42 AM on October 6, 2006


On typewriters, there is a nifty function that erases a character. It's called correction tape.
posted by Not in my backyard at 9:49 AM on October 6, 2006


Best answer: A mechanical "undo" can also be viewed at several levels, and over several lengths of time. At the most basic level, and over the longest time (relative to the device or system's lifetime), a mechanical device can be overhauled, which is a set of repair activities intended to return the device to a state of operational readiness akin to that which it had when new.

In shorter time frames, many mechanical devices are reversible, meaning that their effects on greater systems of which they are a component can be either positive or negative for the function they perform. Pumps and motors are frequent examples of this class of device, and their "undo" action can be nearly instantaneous.

But in a greater sense, because of the laws of thermodynamics, nothing can be truly be undone, in computers, or in mechancial or physical systems, and it is only a conceit of ours as observers that such a concept as "undo" even exists. We imagine that time's arrow can fly in an opposite direction, but imagining does not make it so.
posted by paulsc at 9:49 AM on October 6, 2006 [2 favorites]


Response by poster: Sorry for my lack of clarification.

Pencil traces remain even after erasing...

I meant undo as something dedicated to returning to a previous state.
posted by lorbus at 9:54 AM on October 6, 2006


Response by poster: Paulsc breaks it open!
Undo is an illusion.

Great answers so far guys, now I'm more interested than ever.
posted by lorbus at 9:58 AM on October 6, 2006


I have an old mechanical adding machine, the kind with the hand crank on the side.

There's a button to clear errors in the current entry before the crank is cranked to enter the entry. So it can undo machine state on that section of the machine (actually return it to a known state) while retaining state on the totaling section. Same as clearing so one can re-enter before hitting the add button on an electronic calculator. Would that qualify as an undo?

There is no single button to take a step back once an entry is cranked into the totalling section. But, it is possible to simply make a following reversing entry to return the totalling part of the machine to it's state before the incorrect entry. I'm sure people must have done this all the time in actual practice. Is that an undo?
posted by scheptech at 10:08 AM on October 6, 2006


I remember typwriters sometimes had a ribbon called "lift-off tape" or something similar that when used with the appropriate ribbon (film rather than ink) would physically lift the character off the page with almost no trace remaining. This seems more of an undo than correction tape or similar devices. This was atleast as far back as the 1970's and perhaps even the 60's
posted by TedW at 10:20 AM on October 6, 2006


Best answer: Well, the main question is when it reared its very useful head in the computer world. I would suggest that 'undo' is a function of having non-expert users of systems, and as concept, was ushered in with the advent of the GUI and consumer, to-task applications such as word processors . Before that, users were necessarily experts (or at least very proficient) in the applications they used, and 'undid' mistakes by executing another command, rather than hitting an automatic key combo that rolled back their last action. Given that non-expert users would often not be sure how to completely restore something they had changed (i.e. find and replace of hundreds of words or complex formatting) the 'undo' as a concept needed to come into being to stop thousands of IT support people going insane.

As for mechanical 'undos' - not really possible, given that when you manipulate data, you're dealing with electrons. I suppose there may have been some kind of 'reset' lever on mechanical looms, for instance, but that would have simply returned the loom (or whatever) to its default starting position, rather than undoing some of the weaving.
posted by Happy Dave at 10:38 AM on October 6, 2006


I would suggest that 'undo' is a function of having non-expert users of systems, and as concept, was ushered in with the advent of the GUI and consumer, to-task applications such as word processors.

I dunno. I have hazy memories of having an "undo" function on the version of vi I was using back ~1982, but maybe I'm dreaming that. Anybody out there know for sure?
posted by Opposite George at 6:50 PM on October 6, 2006


Little kids are an Undo for housework.
posted by flabdablet at 9:01 PM on October 6, 2006


Undo existed in the computer well before GUIs. The first time I saw was in ancient EMACS and I do mean ancient.
posted by rdr at 9:05 PM on October 6, 2006


Best answer: Probably the earliest functional "undo" capabilities that I recall being broadly adopted in the computer world didn't happen until the early 1980's, when transactional lock features were added to various commercial Relational Database Management Systems (RDBMS), as a means of insuring database integrity in distributed processing systems.

Transactional locks are all about "undo." Basically, they are ways by which every part of a multi-step process necessary to logically update a database is written first to a transactional log, and then, only after passing some built-in verification logic in the database, are the changes written as a set, to the database. If anything happens to the machine running the RDBMS before pending transactions can be processed, the pending transactions can be "replayed" from the log to automatically update the RDBMS on restart, or, using the logs, transactions can be "backed out" of systems logical to "undo" all the changes as a related set.

The adoption of transactional logging and locks was also influential for file system developers, who used similar ideas to create robust "journaling" file systems, such as XFS, for highly robust system applications, beginning at about the same time.
posted by paulsc at 10:07 PM on October 6, 2006


Words starting with "un" often represent undos - dress/undress, lock/unlock, ....

Though sometimes both acts are independantly lexicalized - open/close. (any more?)
posted by MonkeySaltedNuts at 4:47 PM on October 7, 2006


Response by poster: Thanks for the great answers, the undo dates back a lot longer than I expected!
posted by lorbus at 5:34 AM on October 16, 2006


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