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SEE OUR COMPUTER GLOSSARY!!

This is the boring stuff.  Everybody wants to just jump in the car and start driving, just like everyone wants to just flip the switch and compute.  But, like cars, there should be a license requirement before you log on so that you know what you’re doing. You should know   (1) the size of your computer’s files and (2) the structure that those files are stored in.  The first so that you will know how fast you’re filling up your drives, the second so that you can find whatever you’re created.

I apologize in advance, because there’s no way to make this stuff interesting.  But it’s necessary.  You have to have an idea about the size of your files, graphics, videos, MP3 and other digital items and also the size of the drives and other peripherals required to handle them most efficiently.  Whether it’s the amount of RAM on your main board, your hard drive, DVD burner, flash drive or network backup drive, they’re all expressed in the measurements which follow.  So, like it or not, you have to have at least a relative basic understanding of bits and bytes:

A bit (short for BInary digiT) is the smallest unit of data in a computer.  A bit can have a binary value of either 0 or 1.  Binary means that there are only two logical (i.e. on/off, true/false) choices. Until the value is actually determined, it can have two states. [To learn about other systems with more than two choices per digit, go to BASE-X.]  With respect to the physical storage of bits on a computer’s hard disk drive, the binary value reflects whether the bit is on (magnetic) or off (not magnetic). Click HERE for more explanation.  Think of it like this:  if you wrap lots of copper wire around a rod, then connect each end of the wire to the two poles of a battery, the rod will be magnetized and pick up iron.  When you take one of the wires off of the battery, it’s no longer a magnet.  You’ve turned it on and then off.  There are only those two choices.  That’s binary system (bi = two), and it also demonstrates the relationship between electricity and magnetism, a recurring computer principle.  For more about how your computer computes with binary code, click HERE.

[To confuse the issue slightly more, there’s quantum computing, where the values of data can both (i.e 0 and 1) exist together at the same time (“superposition”) and are known as “qubits”.  But that’s another entirely separate area.  Click on the definitions above if you want to understand this somewhat philosophical data principle.]

A byte is composed of 8 bits.  Similar to the bit, the value of a byte is stored on the hard drive as either above or below a designated level of electrical (therefore magnetic) charge in a single capacitor.  Half a byte (4 bits) is called a nibble.  [Sometimes, the term octet is used for an 8 bit unit instead of a byte.]  Also, in many systems, 4 - 8-bit bytes form a 32 bit word (and sometimes a half-word 16 bits long)]. 

A kilobyte is 1024 bytes (Why exactly 1024 bytes?  Because binary computers count in twos, so 1024 is the closest power of 2 to 1000 (2 to 10th power). Click HERE for more information about this). A megabyte is approximately 1 million bytes (actually, it’s 1,024 kilobytes or 1,048,576 bytes, see the comparison charts below).  Similarly, a gigabyte is 1024 megabytes (1024 megabytes, 1,048,576 kilobytes, 1,073,741,824 bytes); and a terabyte is 1024 gigabytes.   A petabyte is 1024 terabytes.  An exabyte is 1024 petabytes.  And a zetabyte is 1024 exabytes.  The largest current unit of measurement for computer data is the yottabyte, which is 1024 zetabytes. 

As mentioned above, making matters even more confusing, there is terminology distinguishing the above approximations with the exact unit measurements.  For example, a a Pebibyte is exactly 2 to the 50th power, or 1,125,899,906,842,624 bytes and a Mebibyte is exactly 2 to the 20th power, or 1,048,576 bytes.  A mebibyte is 1024 Kibibytes and precedes the Gibibyte as a unit of data storage measurement.  [These exact measurements were introduced by the International Electrotechnical Commission (“IEC”) [see Associations] back in 1998 for those instances where exact data measurement is required.]

A BINARY DIGIT IS A

BIT

8 BITS  IS A

BYTE

  1,000 BYTES     IS A

KILOBYTE

1,000 KILABYTES       IS A

MEGABYTE

1,000 MEGABYTES       IS A

GIGABYTE

1,000 GIGABYTES       IS A

TERABYTE

1,000 TERABYTES       IS A

PETABYTE

1,000 PETABYTES       IS A

EXABYTE

1,000 EXABYTES        IS A

ZETABYTE

1,000 ZETABYTES       IS A

YOTTABYTE

APPROXIMATE

000

,000

,000

,000

,000

,000

,000

,000

YOTTABYTE

ZETABYTE

EXABYTE

PETABYTE

TERABYTE

GIGABYTE

MEGABYTE

KILOBYTE

EXACT

2^80

2^70

2^60

2^50

2^40

2^30

2^20

2^10

YOBIBYTE (YiB)

ZEBIBYTE (ZiB)

EXBIBYTE (EiB)

PEBIBYTE (PiB)

TEBIBYTE (TiB)

GIBIBYTE (GiB)

MEBIBYTE (MiB)

KIBIBYTE      (KiB)

You may find this interesting:  To put the size of a zettabyte in perspective, analyst firm IDC says that the amount of data generated last year totaled about 800,000 petabytes (at 1 million gigabytes each), which is the equivalent of a stack of DVDs that extend from the earth to the moon and back.  The total amount of data projected to be created in the year 2020 is predicted by IDC to be 35 zetabytes, which can be represented by a stack of DVDs reaching halfway to Mars.

BITS VS. BYTES:  Remember that the bytes discussed above are measures of storage, not speed. However, when you see numbers expressed in bits, you’re generally looking a measures of speed.  For example 1,024 bits = 1 Kilobit; 1,024 Kilobits = 1 Megabit; 1,024 Megabits = 1 Gigabit; 1,024 Gigabits = 1 Terabit, and so forth.  Speed is generally expressed in “per second,” as in “10 Gbps” means “10 Gigabits per second”.  For example, a 10 Gbps connection speed would allow you to transfer 75 Gb of stored data (the equivalent of about 110 full CDs of music), over the course of one minute.

As a rule of thumb, a standard page of typewritten text takes up about 2 kilobytes of storage. 500 megabytes would be the equivalent of 500 pages of text. A simple sentence might be composed of 120 bytes, represented by the 120 characters (i.e. letters, digits, spaces, punctuation) in the string.

Generally speaking, you can fit lots of text and numbers into relatively few bytes.  But graphics, music, video and animation can really use up the bytes, requiring more hard drive space to store and play and more power to process.  Luckily, hard drives are at the lowest price in recent history and the addition of drives for storage or backup are quite inexpensive.

GENERAL DISTINCTION:

Data SPEEDS are usually described in terms of BITS:

1,024 bits = 1 Kilobit

1,024Kb = 1 Megabit

1,024Mb = 1 Gigabit

1,024Gb = 1 Terabit

Data STORAGE is usually described in terms of BYTES:

8 bits = 1 byte

1,024 bytes = 1 Kilobyte

1,024KB = 1 Megabyte

1,024MB = 1 Gigabyte

1,024GB = 1 Terabyte

So, for example,  a 10 Gbps connection would allow you to transfer 75GB of data over the course of a minute, or the equivalent of about 110 full CDs worth of music.
 

SO WHAT DO WE MEAN WHEN WE SPEAK OF A 32-BIT OR A 64-BIT COMPUTER OR OPERATING SYSTEM?  Simply stated, 32-bit computers process data in 32-bit chunks, while 64-bit computers process data in 64-bit chunks.  (Yep, that’s the same bits discussed in detail above.)  But this doesn’t mean at all that a 64-bit processor is twice as fast as a 32-bit processor.  It’s not.  First, because a 32-bit processor processes a 64-bit number in two steps rather than one.  Second, because 64 bit code is much more complex and larger and therefore may actually be slower due to higher memory consumption and something called “cache misses.”  How fast 64-bit hardware runs depends a lot on how much RAM is installed on the computer.  The good news is that, while 32-bit computers hit the limit of 4GB RAM (2^32 addresses), the 64-bit computers can access 1.7 billion GB of RAM (2^64 addresses).   While it’s taken a while for computers to make the 32 to 64 bit jump, predominantly because there wasn’t really good software available for 64-bit systems, now we have Windows 7 and 8 64-bit and a number of programs written in 64-bit, and the migration should be quite fast, becoming pretty much prevalent after 2012.  For more, click HERE

What happens if I try to install a 32-bit program on Windows 64-bit, or vice versa? Because Windows has a built-in technology known as WOW (Windows-on-Windows”), the operating system can usually automatically handle either version of a program on most versions of Windows, automatically and seamlessly.

AND WHAT DO WE MEAN WHEN WE SPEAK ABOUT 64 OR 128 BIT ENCRYPTION?  In order to hide data transmitted over the Internet the process of encryption has been developed to hide the data before it is transmitted and reveal it (decrypt it) when it is received.  This is done with an algorithm that can be quite complicated.  The algorithm creates a long sequence of characters.  How long a sequence depends on whether the encryption algorithm is 40, 64, 128 or 256 bits.  The higher the number of bits the longer the key.  Note that the number of bits is not the same thing or length as the number of characters in the resulting key (which is usually less) because, of course, bits aren’t characters.  For more information about how this is actually calculated, click HERE.  And don’t forget that bit length is important for other things, such as the difference between Internet Protocols (“IPs”), as IPv4 addresses are 32 bits in length while IPv6 is 128 bits long.

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