Re: GB vs. MB

Kevin Lentin (
Wed, 27 Nov 1996 16:35:22 +1100 (EST)

Rob Hagopian Wrote ...
> > (Harald Koenig) writes:
> >
> >> I like the disk size message in sd.c but since 1MB == 1024*1024 ==
> >> 2^20,
> >
> >It isn't as simple as that.
> >
> >1MB of RAM is, indeed, equal to 1024*1024 bytes.
> >But 1.44MB floppy has 1.44*1000*1024 bytes.
> >With hard disks, your mileage may vary.
> I don't know of too many SCSI floppy drives though... :-)
> I think that linux should report what's true, not what the marketers shove
> down our throats. A megabyte is 2^20, it should be reported as such.

The change to measuring in millions occured about 5 years ago if memory
serves correctly. I bought a Western Digital IDE drive as a 200MB drive.
And indeed it was 200MB, around 212 million bytes. A week later I bought a
212MB Western Digital for around the same price and was surprised that they
would change the model by 5%. Turned out to be the same drive but they had
redefined the megabyte. Since then, all drive manufacturers have had to
make the same change to compete [WD may not have been the first. They were
the first that _I_ came across].

If you read WD's drive documentation you will see that they explain these
anomolies (eg BIOSes that report in true MB) by saying thet hard drives are
measured in 'decimal megabytes' which are one million bytes. They claim
they are justified in doing so because CHKDSK reports drive sizes using
that unit. This is not true. CHKDSK reports bytes. The drive manufacturers
drop the last 6 digits and attribute an action of theirs to a feature of
CHKDSK. They're wrong, of course.

I still prefer to see computers using 2^20 for a MB even if the drive is
advertised otherwise. The 1.44MB thing is just plain stupid but what can
you do? In that case it's a half decimal, half base-2 megabyte. It's more
like 1.44 thousand K. Complete absurdity.

[     Kevin Lentin               Email:      ]
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