21 Jan
1999
21 Jan
'99
6:56 p.m.
On Jan 21, 21:07, Sam Ismail wrote:
Subject: Re: Reiability of wrong media (was: is out
of 5-1/4" diskettes
On Thu, 21 Jan 1999, Megan wrote:
As Megan pointed out, the maths is wrong. A "1.44MB" disk has 80
cylinders, two sides, 18 sectors per track, sector size 512 bytes.
80 * 2 * 18 * 512 = 80 * 18 * 1024 = 1440KB
That's where the "1.44" number comes from.
And a Megabyte is normally held to be 1024 * 1024 (megabyte would, I agree,
be different, 1000 * 1000). But "1.44MB" refers to 1.44 * 1000 * 1024,
which is a ridiculous way to count. 1440KB = 1.406MB.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
I think the problem with '1.44 Mb' is
that IBM chose to refer to
the exact number of bytes without using the power-of-two term
properly.
For example... on pdp-11s, the virtual address space is always
referred to as 64 Kb... but the actual max (byte) address is
65535. If we were to follow what it appears IBM did, we would
have been referring to 65.5 Kb.
No, a megabyte is not a power of two number. A megabyte = 1,000,000
bytes. So 1.44 megabytes = 1.44 million bytes = roughly 1,440,000 bytes.
So 1.44MB disk drive is not a misnomer.