thousend K (was: Reiability of wrong media (was: is out of 5-1/4" diskettes)

From: Hans Franke <>
Date: Mon Jan 25 07:07:47 1999

Tony's description:
> Let's start with the '360K' disk.
> It has 2 sides, 40 tracks, 9 sectors/track, 512 bytes per sector. The
> total number of bytes is therefore 368640 bytes.
> But since 1K = 1024 bytes, that's also 360K _exactly_. That's the
> formatted capacity, including the space taken up for the root directory, etc.
> Similarly for a '720K' disk. The only difference is that it has 80
> tracks, so it's exactly twice as much storage. _Exactly_ 720K

Taken and agreed.

> But the other sizes are more bogus... The '1.2 Mbyte' disk is 2 sides, 80
> tracks, 15 sectors/track, 512 bytes/sector. That works out as
> 1228800 bytes.
> Now, 1K = 1024 bytes, 1Mb = 1024*1024 bytes = 1048576 bytes.
> So a '1.2M' disk can also be considered as storing 1200K or
> 1.171875Mbytes. That's a little less than 1.2Mbytes, strictly.

Right, and you just missed the chance to give the explanetion.
see below.

> The '1.44Mbyte' disk has 2 sides, 80 tracks, 18 sectors/track, 512
> bytes/sector. That's 1474560 bytes. It's also 1440Kbytes or 1.40625Mbytes
> [...]

> The only way to get the commonly-used names is to take 1Mbytes as
> 1024*1000 bytes. There is no justification for this at all.

Justification ? I don't know, but there's an explanation - we
need some techno archeology - in the AT manual, the 1.2M drive
is nominated as having 1,200 Kbytes of storage - and AFAICT
after digging thru old magazines, IBM didn't advertise it
as 1.2M, only as 5.25" HD. Also, IBM did advertise the 1.44M
drive only as 1440 K 3.5" HD drive - I found also several old
disks that state 1440 K formated capacity on the box and label.

So, my guess is a sinister group of iluminati managed to
twist the systems to keep the people controllable (of course
they are part of the government).

Of course there is also another explanation, where a typical
technical half literate marketing guy combined his old school
knowledge that 1000 k is 1 M with the number 1,200 K (or 1,440 K)
to produce the more easy to advertise 1.2M FD.

And according to Occams Razor, where, whenever two theories
exist that fit the problem, the simplest is right, #1 has
clearly the preference (Or do you think tecnical half literate
marketing people are more likely than iluminati ?).

Have a nice WE

Ich denke, also bin ich, also gut
Received on Mon Jan 25 1999 - 07:07:47 GMT

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