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DADDY BOB'S COMPUTER Q & A
October 29, 2006
Q.
What comes after the Gigabyte, and how many
bytes are there in a Kilobyte, 1000 or 1024?
A.
Well, I'll start by answering the second one
first by saying, 1000 is technically
correct, but as used in today's computer
circles, both can be right. It all depends
on what kind of kilobyte you are referring
to. One definition uses what are called SI
bytes, powers of 10, and the other uses
Binary bytes, powers of 2.
Here is
an explanation of what this is all about. I
suspect that it will be more than you wanted
to know, but while I'm at it I might as well
cover it all.
1000
bytes (103):
This
definition follows the SI standard, and is
recommended for all uses by international
standards organizations using the
abbreviation "kB". The overwhelming
popularity of the 1024 definition means that
anyone using "kilobyte" to mean 1000 in
these situations, although technically
correct, is likely to cause confusion.
However,
it is common to use 1000 when kilobyte is
measuring values which are not based on the
powers of two as in networking,
telecommunications and most hard
drives and DVDs.
1024 bytes (210):
This definition is always
used when referring to
memory, when software refers
to storage capacity, and
other references based on
powers of two. This
definition has been outlawed
by the SI and most
other standards
organizations who instead
recommend the term
kibibyte (KiB).
Although the word "kibibyte"
is seldom seen in practice,
it is starting to be adopted
by software in which
precision is very important.
This definition is used for
nearly all discussions of
file storage sizes and
computer memory since
computer addresses are
naturally powers of two,
making it more practical to
make memory in power-of-two
capacities. Almost all
software manufacturers uses
this definition to express
storage capacity, including
Microsoft, which helps to
explain why the term
kilobyte is so commonly used
in error when it should
probably be kibibyte.
Now you can see one of the
reasons why Windows always
reports the hard drive
capacity as less than the
drive manufacturer. One uses
binary units (2x),
and the other SI units (10x).
See the
table below for a comparison of these two
definitions of bytes, and to answer the
other part of the question, a list of what
comes after the gigabyte.
The SI prefix names were derived like this:
kilo - from the Greek for thousand
mega - from the Greek for great
giga - from the Greek for giant
tera - from the Greek for monster
peta - from the Greek for five (thousand)
exa - from the Greek for six
zetta - from the Latin for seven. (The Greek
hepa for seven was considered but dropped for some
unknown reason. Possibly the fact that the
SI table was conceived by France has
something to do with its irrationality.)
yotta - from the Greek for eight
When the time comes that there is a need for
something larger than the yottabyte, who
knows what it will be called.
Although we are violating someone's standard
by calling 1024 bytes a kilobyte, I suspect
that many will continue to use kilobyte
whether referring to 1024 or 1000 bytes. It
just isn't worth arguing over the difference
unless you are a member of one of the
standards committees.
However, if you want to confuse someone, the
next time you are asked how much RAM memory
your computer has, just tell them 512
mebibytes, or 1 gibibytes. You will be
technically correct, but they'll probably
think you've lost it. |
