Floppies are indestructible

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4 total messages Started by fi... Bela Lubkin Tue, 26 Dec 1989 00:25

#655

Author: fi... Bela Lubkin
Date: Tue, 26 Dec 1989 00:25

44 lines
2456 bytes

Ho ho ho...

Once, in a fit of boredom, I decided to see how fragile floppy diskettes
really are.  Using an Apple //e, I formatted a 5.25" diskette and tested
it with a program that reads every sector and reports how many are
unreadable.  Unsurprisingly, all sectors were readable after formatting.

First I grasped the media with my thumb and forefinger, presumably
getting skin oils on it.  This had no effect.

Next I removed the media from its jacket.  Fortunately, Apple II drives
are able to mount a bare disk, if you're careful to insert it properly.  

I spit on the disk and wiped it on the rug; then carefully cleaned it
off (I didn't want to damage the drive).  This caused one or two bad
sectors.

I printed a document on the dot-matrix printer and slid the disk under
the printhead, printing characters all over both sides of the disk.
This caused the read rate (readable sectors/total sectors) to go down to
about 95%.

I stapled the disk several times, then removed the staples.  Read rate
went down to about 90%.

I filled a large measuring cup with water, rolled the disk up somewhat
to fit it in, and microwaved the whole assembly until the water boiled.
This reduced the read rate to about 80%.

Next I ironed the disk with a regular steam iron.  This *improved* the
read rate to a bit over 85% -- presumbly because it flattened out the
media, which had taken on the curved shape of the measuring cup.

Finally, I scorched the disk in several places with a cigarette.  This
significantly lowered the read rate (55%?), suggesting that cigarettes
are as bad for diskettes as for people...  ;-}

Of course, all it takes is one strategically placed bad sector to make
most filesystem formats unreadable (or at least a big pain to
reconstruct).

Bela Lubkin    * *    //  fi...@gorn.santa-cruz.ca.us  CI$: 73047,1112 (slow)
     @       * *     //  be...@sco.com  ..ucbvax!ucscc!{gorn!filbo,sco!belal}
R Pentomino    *   \X/  Filbo @ Pyrzqxgl +408-476-4633 and XBBS +408-476-4945

Re: Floppies are indestructible

#656

Author: mal... Sean Malloy
Date: Wed, 27 Dec 1989 05:32

28 lines
1780 bytes

In article <117....@gorn.santa-cruz.ca.us> fi...@gorn.santa-cruz.ca.us (Bela Lubkin) writes:
>First I grasped the media with my thumb and forefinger, presumably

>I spit on the disk and wiped it on the rug; then carefully cleaned it

>I printed a document on the dot-matrix printer and slid the disk under

>I stapled the disk several times, then removed the staples.  Read rate

>I filled a large measuring cup with water, rolled the disk up somewhat
>to fit it in, and microwaved the whole assembly until the water boiled.

>Next I ironed the disk with a regular steam iron.  This *improved* the

>Finally, I scorched the disk in several places with a cigarette.  This

This makes Fifth Generation Systems' claims about Fastback Plus (the ad where
they show a disk with a bullet hole in it claiming they got all the data
back anyway) a lot more plausible. With enough redundant storage on a disk,
you can get away with losing a part of the media.


	Sean Malloy {hplabs!hp-sdd, akgua, ucsd, nosc}!crash!malloy
		ARPA: crash!malloy@nosc
	Navy Personnel Research and Development Center
	San Diego, CA 92152-6800
		UUCP: {hplabs!hp-sdd, akgua, ucsd}!nprdc!malloy
		ARPA: mal...@nprdc.navy.mil

Re^2: Floppies are indestructible

#657

Author: ma... jim frost
Date: Sun, 31 Dec 1989 02:34

17 lines
1262 bytes

mal...@crash.cts.com (Sean Malloy) writes:
>This makes Fifth Generation Systems' claims about Fastback Plus (the ad where
>they show a disk with a bullet hole in it claiming they got all the data
>back anyway) a lot more plausible. With enough redundant storage on a disk,
>you can get away with losing a part of the media.

They've been claiming that since the first release.  One trade rag I
used to read actually tried it -- ran in through an electric stapler 5
times, removed the staples, and tried the restore.  Worked without a
hitch.

Unfortunately there used to be places where an unreadable sector made
the whole disk unusable (read: couldn't restore ANYTHING), but they've
fixed that now.

jim frost
ji...@saber.com

Re: Floppies are indestructible

#658

Author: Charles Green
Date: Wed, 03 Jan 1990 03:42

11 lines
1075 bytes

In article <117....@gorn.santa-cruz.ca.us> fi...@gorn.santa-cruz.ca.us (Bela Lubkin) writes:
>First I grasped the media with my thumb and forefinger, presumably
>getting skin oils on it.  This had no effect.

An experience I had with a mag tape someone had touched would indicate that,
although you can still read the existing data,
trying to write over the greasy spot will fail.
Dunno if the grease changes the coercivity of the oxide,
or if it "insulates" the media from the head, or what...
-- 
{decuac.dec.com,cucstud,sundc}!c3pe!charles	ex::!echo Boo:

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