[carapace]

Who recalls the provenance of this old legend about the fellow who challenged his pal to decode a certain floppy?

It was a bog-standard DOS boot disk (IIRC) that he could put in his machine and boot normally. But his pal put it in his computer and... nothing doing, no boot. Analysis of the floppy availed not. The challenge went unmet.

What did our hero do to make the floppy?

.esrever ni nups evird eht os ytiralop etisoppo htiw meht dehcattaer dna ,rotom eldnips evird eht ot seriw rewop eht deredlosed ,evird ksid eht denepo eH

[MisterTea]

This reminds me of a less interesting story:

My father bought a 386 for his work to replace a 286 which only had a 5.25 floppy drive. The 386 had both a 3.5 and 5.25 floppy drive so he quickly switched to the more sturdy 3.5 disks and moved a lot of work to the 3.5's.

Everything was working great until he got a second similarly spec'd 386. For some reason the machines couldn't read each others 3.5" disks. So he called his programmer friend who stopped by and did some testing. Both machines could format/read/write their respective disks no problem. So he formats and writes a test file to a disk from each machine and takes them home with him.

My father gets a call from him the next day: "call the vendor and have them give you a new 3.5 drive in the original machine" Turns out the heads in the original machines 3.5 drive were slightly misaligned mechanically to the tracks. This caused the disk to be perfectly workable in the bad drive but fail to read in any other machine.

[RuggedPineapple]

Somewhat related, but as 800k floppies got harder and harder to find, it became common to just cover one hole on a 1.44 mb floppy so the computers that used them (mostly old compact macs) would treat them as 800k disks. This is fine in the short term but since the tracks and what not don't line up quite right it'll usually degrade over time.

[Zardoz84]

This remembered me when I had a ZX Spectrum +3 as child. At some point, a belt broken and my father replaced with a different belt. So, it can't read anymore my old floppies. I can only use the floppies if I formatted again.

[1996]

The spoiler format is perfectly adapted to the content :)

[AndrewStephens]

Was this fellow a white haired gentleman in a velvet smoking jacket who travelled in a police box? He was always solving problems like that.

[dbt00]

Sometimes there's two of them, and they ytiralop eht esufnoc

[Dylan16807]

> Analysis of the floppy availed not.

It's not a very good puzzle if the only clue is "I dunno he looked at it real squinty and it didn't help."

Apparently any alternate formatting would have tripped up the friend.

[eps]

It's a good story and you are nitpicking.

[Dylan16807]

I was complaining about the framing, not the story. The story is fine as a story.

[carapace]

I didn't want to make up details. I'm asking if anyone recalls the origin ("provenance") of the original story.

IIRC, the friend did various things to the disk to try to figure out what was up.

Think how crazy this magic trick was: you can literally watch it boot a machine, but then put it in another machine and it's just garbage, that should be impossible...

[speps]

> He opened the disk drive, desoldered the power wires to the drive spindle motor, and reattached them with opposite polarity so the drive spun in reverse

[p1mrx]

There's a related practical joke, where the disk is made of antimatter.

[kgwgk]

Hint: If the hero had tried a Plan 9 boot disk on his machine it would have booted into Inferno :-)

[rightbyte]

Would that work for CDs too?

[duskwuff]

It'd take some doing. You wouldn't be able to burn a CD-R backwards without some extra steps; a "blank" CD-R contains some data in the pregroove to identify it as a recordable disc and specify some parameters to the burner. A reverse-rotating drive wouldn't be able to read that data, since it'd be backwards. :)

[szc]

I don't think so, CDs have a spiral track, so the spiral would also have to be reversed.

[Doxin]

Presumably if you'd also flip the phases on the head stepper and move any relevant endstops around you might be able to convince the drive to read disks inside-out.

Fairly sure it'd immediately give up due to pregroove shenanigans but it's an amusing idea.

[anakaine]

Tricky

[anthk]

Use rot13 instead of rev.

[mnw21cam]

It was relevant for the joke.