Units of Computer Storage

Computers (pc, laptop, netbook, tablet pc etc) store information in the form of 1 and 0's in different types of storages such as memory (ram), hard disks, usb drives, etc, to be processed by software. The most of common unit of data storage is expressed as byte which is 8 bits.

For your information, computer data expressed as bytes, kilobytes, megabytes as it is in metric system, but 1 kilobyte is 1024 bytes not 1000 bytes. Data storages starting from the smallest unit are: bit, byte, kilobyte (kb), megabyte (mb), gigabyte (gb), terabyte (tb), petabyte and exabyte. is

What are bits, bytes, and other units of measure for digital information?

A bit is a binary digit, the smallest increment of data on a computer. A bit can hold only one of two values: 0 or 1, corresponding to the electrical values of off or on, respectively.

Because bits are so small, you rarely work with information one bit at a time. Bits are usually assembled into a group of eight to form a byte. A byte contains enough information to store a single ASCII character, like "h".

A kilobyte (KB) is 1,024 bytes, not one thousand bytes as might be expected, because computers use binary (base two) math, instead of a decimal (base ten) system.

Computer storage and memory is often measured in megabytes (MB) and gigabytes (GB). A medium-sized novel contains about 1MB of information. 1MB is 1,024 kilobytes, or 1,048,576 (1024x1024) bytes, not one million bytes.

Similarly, one 1GB is 1,024MB, or 1,073,741,824 (1024x1024x1024) bytes. A terabyte (TB) is 1,024GB; 1TB is about the same amount of information as all of the books in a large library, or roughly 1,610 CDs worth of data. A petabyte (PB) is 1,024TB. Indiana University is now building storage systems capable of holding petabytes of data. An exabyte (EB) is 1,024PB. A zettabyte (ZB) is 1,024EB. Finally, a yottabyte (YB) is 1,024ZB.

Many hard drive manufacturers use a decimal number system to define amounts of storage space. As a result, 1MB is defined as one million bytes, 1GB is defined as one billion bytes, and so on. Since your computer uses a binary system as mentioned above, you may notice a discrepancy between your hard drive's published capacity and the capacity acknowledged by your computer. For example, a hard drive that is said to contain 10GB of storage space using a decimal system is actually capable of storing 10,000,000,000 bytes. However, in a binary system, 10GB is 10,737,418,240 bytes. As a result, instead of acknowledging 10GB, your computer will acknowledge 9.31GB. This is not a malfunction but a matter of different definitions. We count in base 10 by powers of 10:

101 = 10 102 = 10*10 = 100 103 = 10*10*10 = 1,000 106 = 1,000,000

Computers count by base 2:

21 = 2 22 = 2*2 = 4 23 = 2*2*2 = 8 210 = 1,024 220 = 1,048,576

So in computer jargon, the following units are used:

Unit Equivalent 1 kilobyte (KB) 1,024 bytes 1 megabyte (MB) 1,048,576 bytes 1 gigabyte (GB) 1,073,741,824 bytes 1 terabyte (TB) 1,099,511,627,776 bytes 1 petabyte (PB) 1,125,899,906,842,624 bytes

Memory of storage capacity measurement

We come across different measuring units like kilogram, meter and liter and so on to measure weight, length and capacity or volumes of different commodities. Similarly, when we have to measure the capacity of computer¶s memory, storage devices and length of programs, units like kilogram, meter and liter can not be used. Hence, we use the units like BIT, NIBBLE, BYTE and WORD.

BIT BIT is an abbreviation of the words binary digit and is the smallest units of information. It is either µ0¶ or µ1¶. The raw data fed into the computer are first converted into an electrical pulses or BITs, as the computer do not recognize the general form of data like numbers (0-9), alphabets (a-z or A-Z) and special characters like punctuation marks and arithmetic signs. The 0 and 1 of the binary system corresponds to the ON and OFF of the flow of electrical in the computer¶s circuits. Computer works by recognizing the presence or absence of an electrical pulses or BITs at a particular time. NIBBLE A NIBBLE is a string of four BITs. The earliest form of code, called µBinary Decimal Code (BCD)¶ used a NIBBLE for every character. For example: Character 3 A BCD (NIBBLE) 0011 1010 BYTE It is the unit of measuring computers memory and size of a program. One BYTE is the string of eight binary digits (BITS). It may represent a single letter, numeral or other characters. Computer memory is expressed in terms of Bytes, Kilo bytes(KB), Mega bytes(MB), Giga bytes(GB) and Tera bytes(TB). 8 bits = 1 byte 1024 bytes = 1 kilobyte (KB) 1024 kilo bytes = 1 Mega byte (MB) 1024 mega bytes = 1 Giga byte (GB) 1024 giga bytes = 1 Tera byte (TB) A µKilo¶ should mean 103 (10×10×10) that is 1000 bytes. However, since the computer used Binary system and 210 (i.e. 2×2×2×2×2×2×2×2×2×2) equals to 1024 bytes, which is nearly 1000 bytes. Hence, µKilo¶ refers to 1024 in measuring units of computer.

WORD A computer word is defined in terms of bytes. A word may be formed by combining two or more bytes. The most common combination if of four bytes. Word-length is a length of bits that occupy one location in memory. A computer having a smaller word-length is slower that another having a larger word-length is, though the speed of both is same. Word-length is generally fixed for a computer, but some computers have a challengeable word-length i.e. they can be used in doing small or big tasks. Nowadays computers have word-length of 16, 32, 48, 64, 128 or more bits.