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I have the vague recollection of "Panic Ejecting" floppy disks by lifting the latch on the drive after immediately regretting a command I had typed. At the time, I was young, impulsive, and blessed with only enough computing knowledge to be dangerous.

This likely happened first on the school's TRS-80 Model III, though it is possible I also did the same with my Commodore 64 or a friend's Apple ][.

The most likely scenario, if my memory is accurate, was typing "SAVE" at the BASIC command line when I meant to type "LOAD". Programming BASIC one tended to SAVE the program often, creating a type of "muscle memory". This could lead to quickly typing SAVE, and committing an experimental change to disk, when what you really wanted to do was revert.

For this specific example, how effective would it be punching out early / hitting the Eject as soon as you realized your mistake?

For similar experiences of regretting a disk command on early 8-bit systems, how successful might this be for other scenarios?

  • We did the same thing on our Apple IIc...I have no idea if it worked, but my brother swore by it if he died in Castle Wolfenstein, so at least anecdotally, it worked – Quasi_Stomach Apr 7 at 16:58
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    Castle Wolfenstein is the canonical 80s example of yanking a disk from the drive to prevent the game from deleting your save file when you died. Runner-up is Floyd in Planetfall saying "Oh, boy! Are we going to try something dangerous?" when you saved the game. – Jim Nelson Apr 7 at 17:04
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    NOTE: "data loss?" is not a yes/no question. If the command you typed is going to cause some number of blocks to be written, that will take some time. Depending on when you unlatched the drive, none or some or all of the blocks may be overwritten. Suppose it's "some." Will you be able to find the ones that weren't overwritten, and read them? That isn't a yes/no question either. The degree of difficulty will depend on how the file system works, on luck, on your tools and/or skills, and I don't know what all else. – Solomon Slow Apr 7 at 17:36
  • @Jim, but Floyd wanna play Hider go Seeker! – Geo... Apr 7 at 18:58
  • Ultima III is another culprit. At least in the earliest ports, it auto-saves as soon as one character dies. If the last one dies, continuing with that saved game becomes impossible. Very annoying. A list of hints for the games in the German "64er" magazine even stated that, when going to the hidden land Ambrosia "don't yank out the disk" because what happens looks similar to your whole party dying. – TeaRex Apr 8 at 7:08
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I did that all the time on the Apple II. The reason it worked was that some time was needed for the motor to spin up to the correct speed, and that the Disk II didn't really have an "eject" mechanism, but that you could very directly mechanically lift the read-write head from the surface of the disk.

That meant that if you were quick enough to lift the latch just when the drive light turned on, you could prevent a write with 100% percent success rate.

Important for some games.

The possible failure mode is that some sector would be half-written, and therefore it wouldn't be possible to read it again, but that never happened to me.

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    I definitely remember doing this on PCs with 5.25" drives as well (not often, but when I'd done something dumb [not uncommon] and immediately realized it [less common]). Mechanical open/close FTW! I remember being frustrated by a 3.5" drive that wouldn't let me do it -- the mechanism was still mechanical, but it had a lock or something it would put in place when the drive was spinning. :-| – T.J. Crowder Apr 8 at 14:59
  • @T.J.Crowder I always wondered if the PC drives had a shorter spin-up time than the Apple II drivers. I think I never tried this stunt with a PC drive. – dirkt Apr 8 at 16:39
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Theoretically, yes.

The disk needs time to spin up to speed before reading or writing can occur. While it varies between platforms and drives, it's at least a couple hundred milliseconds. That's arguably just enough time to realize you shouldn't have hit enter, and to pop the drive latch. Especially if you subconsciously realize it before you even hit enter and then hit enter anyway, like I usually do.

But if you're not fast enough, you can absolutely end up writing garbage to the disk if you interrupt it mid-write.

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    Even if you corrupt the disk, it might be better than nothing. Wiping out the first few sectors of a file is a lot worse that wiping out the whole file, especially if you are up to the challenge of reconstructing the blown up portions to salvage what you can... – Geo... Apr 7 at 19:01
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    it also needs to seek to the proper sector. That gives you a few more milliseconds to react – Jean-François Fabre Apr 7 at 19:47
  • If a game for the C64, Apple II, or other system that allows direct control over the drive electronics were designed to ensure instant invalidation of information on disk. If loading a game required that some track be entirely valid, and the head was left sitting on that track, it would probably take less than 1/60 second to start invalidating data on that track. If there was no need for the "scribble data" to be readable, there would be no need to wait for the drive to be up to speed. – supercat Apr 8 at 20:43
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    Depending on the machine, it might need to spin up, seek to the directory (probably in track 0), wait for the head to settle and the disk to rotate to the correct position, read one or more sectors, then seek to the relevant track, and wait again, before it could begin to write anything. IIRC, all that could take a few seconds, so I wouldn't be at all surprised to find you could open the drive door first. Would be risky, though! – gidds Apr 8 at 23:13
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As a former floppy disc repair technician, you can indeed do this, but you risk damaging the read-write heads and/or the alignment of the heads, rendering the drive unusable until it is repaired or replaced.

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  • Didn't most 5.25 drives (slim style drives below half height excepted) mechanically link the drive locking lever with the head lift mechanism? – rackandboneman Apr 8 at 19:40
  • In that case, whilst the media is still spinning, the drive would keep you from being able to open it, thus the write operation would continue anyway, so no point in trying to stop it. If one were to try to force it, even more damage would certainly occur. – Bjorgen Eatinger Apr 8 at 20:46
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    I used drives with several different types of drive door, and all of them not only let you open the drive at any time, but also unloaded the head as part of the door-open mechanism. So doing that while the drive was running shouldn't cause any physical damage — though of course it could corrupt the data if it was writing at the time. – gidds Apr 8 at 23:17
  • Those must have been very old drives, which did not also attempt a partial eject of the disc itself. I worked in the area of the factory performing drive head alignment, and most of the drives that came in for me to repair, had been tampered with in the manner described above. It's just not a good idea. – Bjorgen Eatinger Apr 10 at 2:04

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