21 Jan
1999
21 Jan
'99
8:56 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. 
21 Jan
21 Jan
9:11 p.m.
On Fri, 22 Jan 1999, Pete Turnbull wrote:
Yes, 1,000,000 bytes (a megabyte) + 440,000 bytes (.44 megabytes), ergo
1.44MB.
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.
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.
Well, I guess it depends on if you're going by the classical defintion of
a computer 'K' which is 1024 bytes (2^10), or what the literal meaning of
'megabyte' is, which is "one million bytes". Semantics!
Find me an authoritative reference that defines a megabyte as 1024 * 1024
bytes and I'll eat a pancake.
Sellam Alternate e-mail: dastar(a)siconic.com
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22 Jan
22 Jan
7:30 a.m.
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11:58 a.m.
M (1) Prefix mega; 1,000,000. (2) When refering to
computer storage
capacity, 1,048,576 (1,048,576= 2 to the 20th power)
Also
Mb 1,048,576 bytes.
Incidentaly, it also defines
Gb 1,073,741,824 bytes (=2^30 ARD)
Just on a side note, I always thought that the proper way to state
the abbreviations were MB and GB _not_ Mb and Gb. With the
caps B meaning Byte and the little b meaning bit. So 8Mb would
be 8 MegaBits while 8MB would be 8MegaBytes, ethernet would
be 10Mbps while fast SCSI is 10MBps (slight difference).
George
12:18 p.m.
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2:30 p.m.
On Fri, 22 Jan 1999, George Currie wrote:
Just on a side note, I always thought that the proper
way to state
the abbreviations were MB and GB _not_ Mb and Gb. With the
caps B meaning Byte and the little b meaning bit. So 8Mb would
be 8 MegaBits while 8MB would be 8MegaBytes, ethernet would
be 10Mbps while fast SCSI is 10MBps (slight difference).
There's a reason why I personally rarely reduce abbreviations all
the way to two characters. I usually use {K|M|G}b{y|i}t[e][s]. If
I leave it at just {K|M|G}, assume bytes.
--
Ward Griffiths
"the timid die just like the daring; and if you don't take the plunge then
you'll just take the fall" Michael Longcor
2:12 p.m.
On Fri, 22 Jan 1999, Tony Duell wrote:
Can you find a reference (other than an advert :-))
that defines it any
other way?
Anyway, I might accept that 1Mbyte = 10^6 bytes, particularly if you
happen to have a decimal or BCD machine :-) (this is classiccmp). But I
don't see any justification for making it 1024000 bytes. And that's the
only way you can have '1.44Mbytes' on a HD 3.5" disk
And we get the 10^6 error as well of course with the Atari STs, models
520 and 1040.
--
Ward Griffiths
"the timid die just like the daring; and if you don't take the plunge then
you'll just take the fall" Michael Longcor
25 Jan
25 Jan
2:15 a.m.
New subject: Atari Numbers (was: Reiability of wrong media (was: is out of 5-1/4" diskettes)
Anyway, I
might accept that 1Mbyte = 10^6 bytes, particularly if you
happen to have a decimal or BCD machine :-) (this is classiccmp). But I
don't see any justification for making it 1024000 bytes. And that's the
only way you can have '1.44Mbytes' on a HD 3.5" disk
And we get the 10^6 error as well of course with the Atari STs, models
520 and 1040.
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ard＠p850ug1.demon.co.uk -
dastar＠ncal.verio.com -
g＠kurico.com -
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pete＠dunnington.u-net.com