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SubjectRe: patch for sd.c: fix MB vs. GB
On Mon, Dec 28, 1998 at 07:03:34PM -0500, C S Hendrix wrote:
> In message <Pine.LNX.3.95.981228174336.233A-100000@chaos.analogic.com>, "Richar
> Is it acceptable? Depends on your POV.
>
> > 18 * 160 * 512 = 1,474,560
> > / 1024 = 1,440
> > / 1024 - 1.40625
> >
> > It looks to me as though the world has been dividing megabytes by 1,000
> > to get gigabytes all along.

Sorry to respond to the wrong poster, I'm missing the previous post.

People have been fiddling the definitions for a while. Somehow the 1440K
floppy became a 1.44 meg for some bizare reason and it stuck.

The hard drive world is even worse. They deal in 'decimal megabytes'. I kid
you not. That is the term used in the WD manuals. They claim that because
CHKDSK reports space in 'decimal megabytes' [1,000,000 bytes], they should
report hard drive capacities in the same. Of course, CHKDSK does no such
thing. CHKDSK reports bytes, with 1000 separators and makes no claim about
megs or gigs at all.

The truth is that one of the hard drive manufacturers decided one day to
redefine the megabyte and hard drive capacities have been overstated by
4.8576% ever since. In fact, I can pinpoint when it happened - I bought a
Western Digital Caviar 200MB drive many years ago when 200MB drives were
top of the line. (The drive was actually 202MB). About 2 weeks later I
noticed that pricelists were quoting a WD 212 meg drive. I bought one of
those for another system for the same price and was most annoyed to
discover that both drives are 989/12/35 (sometimes 987/12/35) yet magicaly
one is bigger than the other. Of course 989*12*35*512 is 212674560 which is
202MB in reality, 212MB in hard drive manufacturer land.

The difference in sizes is now into the 100's of megabytes.

Also, some people (like hard drive salesmen) will try persuade you it has
something to do with formatted capacity - bullsh*t - it's purely marketing.

The 1.44MB floppy is half way in between. Very weird.

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