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A bit
about bytes
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One question I
hear all the time goes something like this:
"I just bought a new 40 GB
hard drive, but when I put it in my computer the computer only shows it
as being a 37.2 GB hard drive.
Why is that?"
For those of you that want
the straight answer, here it is:
40,000,000,000 divided by 1,073,741,824
multiplied by 1,000,000,000 = 37,252,902,985 or 37.2
GB
Well that's
confusing!
To understand the answer to
this question you need to understand a bit about bytes and
advertisement.
So let’s
start with the basics
A bit about bytes
Many people get confused or
misunderstand abbreviations like KB, MB, GB as well as Kb, Mb. When you
say Kilobyte what does that really mean? What’s the difference between a
Kilobit and a Kilobyte? These bits and bytes will often get used
incorrectly or people use them without knowing what they mean.
Here are the basics of the bit.
A computer is actually just a bunch
of switches that you turn on or off. Just like a light switch, the only
data that a computer can understand is, is it on or off.
But those two simple commands can be grouped into millions of
combinations and it is the way they are grouped that creates complex
data.
The basic unit is called the bit. This comes from
the b
in binary
and the it
in digit.
If a bit is on, it is represented by the number 1.
If the bit is off it is represented by the number 0.
Just like the letter j has little
meaning by itself, a bit by itself can only be on or off.
Bits are grouped together just like
letters to make more complex codes. When you add several letters
together, you make a word. When you add eight bits together you make a
byte.
The combination of eight bits gives
us 256 possible combinations of 1 and 0. This is what gives us numbers
and letters on the computer called the ASCII code. Just as letters are
the building blocks of language to make words, bytes are the building
blocks of language for a computer.
The eight bits or one byte 10000001
equals the capital letter A in the ASCII code.
When we abbreviate the word bit we
use a lower case “b”. When we abbreviate the word byte we use an
uppercase “B”. Bits and bytes can be expressed in larger measurements.
They are generally expressed in exponents of two known as binary code.
Now you know the basics of the bit
lets move on to what the kilo and giga stuff is.
Counting on toes
When I was in school everyone was
talking about the Metric System and how everything was going Metric. The
metric system uses the powers of ten when counting. This is made easy
because we have ten fingers and ten toes. The power of ten has been with
us our whole life.
We know 1X10=10; 10X10=100;
10X10X10=1,000 and so on.
This is called the power of ten.
In the metric system a unit of 1,000 is a called a
Kilo and 1,000,000 is a Mega. With this in mind 1,000 grams becomes a
Kilogram.
|
Units |
Prefix |
Power of 10 |
Number |
|
Thousands |
kilo |
103 |
Ten to the 3 power = 1,000 |
|
Millions |
mega |
106 |
Ten to the 6 power = 1,000,000 |
|
Billions |
giga |
109 |
Ten to the 9 power = 1,000,000,000 |
|
Trillions |
tera |
1012 |
Ten to the 12 power = 1,000,000,000,000 |
|
Quadrillions |
peta |
1015 |
Ten to the 15 power = 1,000,000,000,000,000 |
|
Quintillions |
exa |
1018 |
Ten to the 18 power =
1,000,000,000,000,000,000 |
|
Sextillions |
zetta |
1021 |
Ten to the 21 power =
1,000,000,000,000,000,000,000 |
|
Septillions |
yotta |
1024 |
Ten to the 24 power =
1,000,000,000,000,000,000,000,000 |
OK that’s easy enough. We use units of
10 everyday when we use money.
But remember a computer doesn’t have
any fingers or toes. It only knows two digits 0 and 1. When the computer
counts it counts in units of two.
Look out Luke,
Yottabytes
Because a computer only has two
digits to count with it would be vary difficult to write programs using
the decimal system. So instead we use the binary system or system of 2.
In the binary system 1X2=2; 2X2=4;
2X2X2=8 and so on.
This is called counting by the power
of two and is the beginning of the numerical system for computers.
We took the names Kilo, Mega and Giga
and so on from the Metric system. However, because the computer counts
in binary it uses power of two instead of ten. So instead of a kilo
being 1,000 for a computer a kilo is 1024
|
Abbreviation |
Name |
Power of 2 |
Formula |
|
b |
Bit |
20 |
Two to the 0 power = 1 (true) or 0 (false) |
|
|
Nibble |
22 |
Two to the 2 power = 4 bits |
|
B |
Byte |
23 |
Two to the 3 power = 8 bits = 1Byte |
|
|
Wyde or Halfword |
24 |
Two to the 4 power = 16 Bits |
|
|
Word |
25 |
Two to the 5 power = 32 Bits |
|
|
Double or Double Word |
26 |
Two to the 6 power = 64 Bits |
|
|
Quad or Quad Word |
27 |
Two to the 7 power = 128 Bits |
|
KB |
Kilobyte |
210 |
Two to the 10th power
= 1024 B = 1 KB |
|
MB |
Megabyte |
220 |
Two to the 20th power = 1,048,576 B = 1,024 KB
= 1 MB |
|
GB |
Gigabyte |
230 |
Two to the 30th power = 1,073,741,824 B =
1,048,576 KB = 1,024 MB |
|
TB |
Terabyte |
240 |
Two to the 40th power = 1,099,511,627,776 B =
1,073,741,824 KB = 1,048,576 MB = 1,024 GB |
|
PB |
Petabyte |
250 |
Two to the 50th power = 1,125,899,906,842,620
B = 1,099,511,627,776 KB = 1,073,741,824 MB = 1,048,576 GB |
|
EB |
Exabyte |
260 |
Two to the 60th power =
1,152,921,504,606,850,000 B = 1,125,899,906,842,620 KB =
1,099,511,627,776 MB |
|
ZB |
Zettabyte |
270 |
Two to the 70th power =
1,180,591,620,717,410,000,000 B = 1,152,921,504,606,850,000 KB
|
|
YB |
Yottabyte |
280 |
Two to the 80th power =
1,208,925,819,614,630,000,000,000 B = 1,180,591,620,717,410,000,000
KB |
|
** |
Zeptobyte** |
290 |
Two to the 90th power =
1,237,940,039,285,380,000,000,000,000 B =
1,208,925,819,614,630,000,000,000 KB |
|
** |
Yoctobyte** |
2100 |
Two to the 100th power =
1,267,650,600,228,230,000,000,000,000,000 B |
|
Warning
technical disclaimer below |
|
** (Note: Zepto and Yocto are
unofficial and does not follow SI order) |
The last two on the list Zepto
and Yocto are becoming more accepted but have not become official by
the ISO.
All numerical prefixes are defined by
the
International Standards Organization in a
document called ISO 1000,
"SI
units and recommendations for the use of their multiples and of
certain other units." |
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To put this in some perspective (or
not),
it would take approximately 86 trillion years
to download a 1-yottabyte file.
The entire contents of the Library of Congress would consume a mere
10 terabytes.
As stated
by
www.wordspy.com |
Dat’a Latabites
OK,
did you learn a lot?
What about our question? Have you figured out the answer?
Why would a hard drive (a computer component) be advertised as 40
Gigabytes when we know a computer only sees it as 37.2 GB?
The answer is that the computer is
not selling the hard drive, used car salesmen are. (Sorry Dad)
What I mean is; hard drives
manufacturers want to make you think you are getting more than they are
selling. When they put the 40 GB on the outside of the hard drive they
use the metric system. But your PC will only ever use the binary system
to read it.
To find out the binary size of the drive you must divide the metric size
40 GB by one gigabyte binary and multiply by 1,000,000,000.
40,000,000,000
Ah the power of advertisement.
Next month Ad-ware, Spy-ware and
Mal-ware brought to you by the people who do advertisements.
This article by Robert Mountain
Some information and
some quotes for this article came from:
www.wordspy.com
http://acronymsonline.com
http://www.edepot.com/science.html
http://www.whitman.edu
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