Computer Measurement Units

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 ‘0’ or ‘1’. 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 ‘Binary 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 ‘Kilo’ 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, ‘Kilo’ 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.