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Why do you drag a disk image the trash?
History behind the shortcut

By:David K. Every
©Copyright 1999

Someone asked me via email, "Why do you drag a disk image to the trash? Where did that behavior come from?" When you understand the history, it makes the behavior more clear -- and helps people understand why it isn't as inconsistent as people think.

In original Macs you only had a floppy drive and no hard drive -- all disk images were removable. Floppy drives were expensive and most people only had one. The normal behavior for "Ejecting" a disk (1) was to eject the disk, but to not forget about the image -- you didn't want to have the image of the disk go away, normally you wanted to keep a shadow image of it around on the desktop.

(1) This was the Menu Item "Eject", under the special menu. It had a shortcut behavior of Command-E for eject.

The reason that people wanted to normally have a "shadow image" of disks around was because that allowed users to work with more than one disk at a time. Even though you inserted a new disk you could still see the original (in ghostly form). Since you could still see the original, you could drag files or folders from one disk to the other to do file or folder copies -- and the Mac would happily ask you to insert the proper disks (in sequence) to do the copy. This shadow image allowed for "direct manipulation", and most people "got it" right away -- it was pretty intuitive. The Mac was smart enough to know that if you double clicked or tried to open something that was on a shadow-image that it would ask you to insert the correct floppy so that it could proceed. It was all so logical, and almost everyone that tried the Mac just loved the Mac because of its intuitiveness.

The Mac way was better than the PC way of typing commands. The Mac way saved users from having some complex copy utility (mode) or a command. Every Command Line (DOS) of the time used a different syntax for whether they wanted the command to be a "TO" as in "copy source [to] destination", or a "FROM" command as in "copy destination [from] source" (without the brackets to give you a clue), so users were usually getting it wrong (not to mention the complexity of pathnames and forward versus backwards slashes and so on). Of course you could run utilities, or set parameters to make things behave differently, just to make sure nothing was as consistent as the Mac.

The Mac way was still a little bit painful on a Mac128. The Mac's floppy had a whopping 400K of storage, or up to 3 times more storage than the 160K (or later 320K) that PC's floppies had. Since the Mac used about 1/2 of its RAM memory for the System and Finder, it only had a little bit of memory left -- so a file copy was done 64K at a time, with the machine ejecting one disk and asking you to please insert the other, up to 10 times on a full disk. This got much better with the Mac512's, which had far more memory (512K), and disks could be copied in a few swaps -- but then things got worse again with the Mac 512KE when Apple doubled the disks capacity to 800K (a little while later PC's got 720K Disks, and even started going to the 3 1/2" floppy that Apple had popularized). The "Please Insert Disk X" dialog was a well known site to us dinosaurs that used Macs in '84 and '85.

But there was still a "hole" -- what if you didn't want all these "shadows" of every disk that you'd ever inserted lying around cluttering up your desktop? Those shadow images could get confusing and untidy. Each disk image not only cluttered the desktop, it took a little memory away -- and with only 128K of memory (in those early days), memory was precious and these images could add up. So sometimes you wanted to eject a disk AND forget about the image. What to do?

Well the Mac needed a separate command called "Put Away" (2).

(2) This was moved to the file menu, since it could be used for files as well as disks. Also I don't think they wanted it too close to the "Eject" to avoid confusion or accidental selection of the wrong item.

The "Put Away" command would move a file or folder that was on the desktop to wherever on the floppy disk the file had originally come from. And "Put Away" on a Disk image would eject that disk AND it would forget about the Image (remove the shadow image from your desktop) -- it meant what it sounded like, that you were going to put the disk away (and not use it anymore). Again, all this was very intuitive, and most people "got it" right away. It was logical.

But part of the Macs advantage went beyond just having logically arranged and easy to find menus (with the most common ones have keyboard shortcuts) -- though both those concepts were new. The Mac also tried to use direct manipulation (intuitive actions) to make things even easier. You didn't have to just select the close menu to close a window, you could go right onto the window itself and hit a little close box control -- directly manipulating it. The Mac didn't even have commands to move a window, you just selected on the window and moved it directly (with the mouse). And so on. Many common actions had a "direct manipulation" equivalent. So how to do that with "Eject and Forget" or the "Put Away" action? Well the answer was fairly obvious -- why not just drag the disk to the trash can (3)? Meaning you want to "trash" the image of the disk (not the data itself). Not perfect -- but pretty good.

(3) Remember, you wouldn't want to make "dragging a Disk to the trash" actually erase the disk, since erasing a disk is very rarely used and a very destructive behavior (to avoid accidental data loss you don't want to make too easy to do). So since that behavior wasn't used for anything else (and wouldn't make sense as anything else), and you were trying to "trash" or eliminate the image of the disk (just not the data on the disk) it was the most sensible direct-manipulation shortcut for doing that -- and Put Away was a common enough action that you really did want a shortcut. Reasonable compromise when you think about it.

Of course most Mac users would scratch their heads when first told of that shortcut -- "that won't hurt anything?" -- but it was a SHORTCUT! The proper way was to use the "Put Away" menu, or the shortcut key (added later) for the Put Away menu (Command-Y). The irony is that the shortcut was so surprising that users remembered it immediately. You told people once about dragging a disk to the trash (to forget about the image) and they remembered that behavior, and forgot about the menu or keyboard shortcut -- mainly because users were a little surprised that the behavior didn't delete everything on the disk without warning (like other computers of the time would have done, if they had User Interfaces). So the shortcut stuck, and it was because the action was so curious that it was so memorable -- and now no one remembers the real way a disk was supposed to be "put away".

Later Additions

By 1985 or 1986 it was becoming more common to have Hard Drives to do file / folder / floppy copies -- and it wasn't worth worrying about direct disk-to-disk copies very often. Later still we got 'removable' hard disks (Syquest's, Zip, Jazz) and CD-ROM Discs -- and the drag-to-trash to "Put Away" behavior just carried over.

System 7.5 or Mac OS 8, had far larger removable storage, it was far less common to want to keep a shadow image of a floppy, CD, or removable disk around. Most people that were copying floppies would just copy the whole disk to the hard-drive first, then back from the new disk (from hard drive image) -- this was faster than disk swapping anyway. Copying the many MegaBytes of storage on most removable drives (through a Finder Copy) just didn't make much sense. So Apple finally changed the old behavior -- instead of "Ejecting" a disk leaving the shadow image around, the default Eject became the exact same thing as "Put Away".

For a few OS versions you could Option-Eject (or some similar shortcut key) to keep a shadow image around, for those few that still wanted to do that, but when I tried it under 8.5, I could no longer find references or the key sequence to do that -- so it looks like the old behavior is gone.


Most people don't remember why things evolved as they did. For a brief while (when working on Copland / Maxwell -- the Original System 8) Apple added a behavior where when you selected a disk the trash can changed to look like a floppy/disk being ejected -- the idea was that was more intuitive. I think after a few user studies showed that the Trash can suddenly changing (whenever you selected or started dragging a disk) was just as disconcerting (or more so) than the behavior itself. So that fix was wisely dropped.

There are some interesting lessons to be learned about legacy and "intuitive" in all this.

  1. Bad behaviors are forever
    OK, not really, but behaviors do hang around for a lot longer than they make sense. Yanking them away confuses people, so it is often better to stick with a bad User Interface rather than to have to retrain everyone (or field the 1,000's of tech support calls that you will get complaining when you remove something).
  2. Inconsistent and shocking can be very memorable
    The reason the shortcut (drag-to-trash) stuck, is because it was so shocking and to some seemed illogical and inconsistent at first (but made sense when explained). It wasn't THAT bad, but it was enough of a surprise to stick in peoples minds -- so much so that it displaced the proper behaviors (menu command / keyboard shortcut).
  3. System Requirements change
    What makes sense in the days of $500 400K floppy drives (as primary storage) may be less sensible in the days of a $99 100 MB removable disks. Things change.

Either way, I don't mind the "drag-to-trash" behavior -- and think the Mac is a (barely) better system with it. The behavior is somewhat an anachronism but it isn't isn't as bad of interface as people think (or as much as some Anti-Mac people imply). Let's face it, if it was THAT bad then no one would have used it, and everyone would have used the menu or shortcut key sequence instead.

Created: 01/01/98
Updated: 11/09/02

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