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1.2 Characteristics of Computer


Computers have distinguishing characters which make them ideal machines. But they do not certain have characters which human possess. Some of the important characteristics of computers are:

i]    Automatics:
       ►  Computers are automatic machines which once started a job; carry it on until it is completed       provided they are given the required instructions by the users.

ii]   Speed:
  The computers are capable of taking logical decisions, performing arithmetic and non-arithmetic operations on alphabets and copying at an unbelievable speed.
►  The units of speed for a computer are in milliseconds (10-3) or even in nano and Pico second (10-9 or 10-12)
    A powerful computer can perform 3 to 4 million arithmetic operations per second.
  The speed of the computers is attributed to the fact that The Computers Are Electronic Devices Working On Electrical Pulses Which Travel at High Speed.

iii]     Accuracy:
 The computer produces highly accurate and reliable results
 The errors in the calculations may be due to the error in the logic of the human but not due to the computer.
 The computers perform accurate calculations 'n' number of times.


iv]      Versatility:
 A computer is capable of performing a wide variety of functions.
 It can accept data and produce results.
 It can perform the basic arithmetic and logic operations.
 It can transfer data internally
 Severally applications can be run at a time. For example MS Powerpoint, Adobe Pagemaker and Windows Media Player can be run at a time.

v]     Diligence:
►  A computer is capable of performing the same task over and over again with the same degree of accuracy and reliability as the first one.
►  This is because, unlike human beings, computers are free from monotony, tiredness, lack of concentration etc. and can work hours together without creating bugs.

vi]      Large and Perfect Memory:
►  A computer can store and recall any amount of information because of its secondary storage capability with perfect accuracy unlike human beings.
►  The storage capacity of the computer is enormous and is perfect.
►  A computer recalls a data with greater accuracy even after several times and does not lose any information unless it is prompted to do so.

vii]    No I.Q and feelings:               
►  A computer is not intelligent on its own and cannot think its own.
►  It can only perform the tasks specified by the human.
►  It cannot decide on its own and only the user can determine what the computer must do.
►  A computer has no feelings but a human does.

Table 1.3: Measures of capacity
Kilo-(K)
1 Thousand
= 103 and 210 bytes
Mega-(M)
1 Million
= 106 and 220 bytes
Giga-(G)
1 Billion
= 109 and 230 bytes
Tera-(T)
1 Trillion
=1012 and 240 bytes
Peta-(P)
1 Quadrillion
=1015 and 250 bytes

Bit/Binary Digit:
(Represent single bit either 1 or 0 or ON or OFF). A binary digit is logical 0 and 1 representing a passive or an active state of a component in an electronic circuit.

Nibble: 4 bits or ½ byte = 1 Nibble = Group of 4 bit

Byte = 1 character. A group of 8 bits is called byte. A byte is the smallest unit, which can represent a data item or a character.

Word (2 bytes or 16 bits): = 1 Word. A computer word, like a byte, is a group of fixed number of bits processed as a unit, which varies from computer to computer but is fixed for each computer. The length of a computer word is called word-size or word length. It may be as small as 8 bits or may be as long as 96 bits. A computer stores the information in the form of computer words.

2 Words or 32 bits = Double word
1024 Bytes
1 Killobyte (KB)
210 or 103
1024 KBs
1 Megabyte (MB)
220 or 106
1024 MBs
1 Gigabyte (GB)
230 or 109
1024 GBs
1 Terabyte (TB)
240 or 1012
1024 TBs
1 Petabyte (PB)
250 or 1015
1024 PBs
1 Exabyte (EB)
260 or 1018
1024 EBs
1 Zettabyte (ZB)              
270 or 1021

How many bytes equal to 1TB?
Here, from the above table we have observed that:
1 TB = 1024 GB
= 1024×1024MB
=1024×1024×1024KB
=1024×1024×1024×1024 Bytes
= 1099511627776 Bytes

Table 1.4 Measure of Time and Speed
Unit of Time
Meaning
Part of Second
In the power of 10
Millisecond (m)
Thousandth of a second
1/1000
10-3 sec.
Microsecond (m)
Millionsth of a second
1/1000000
10-6 sec.
Nanosecond (n)
Billionsth of a second
1/000000000
10-9 sec.
Picoseconds (p)
Trillionth of a second
1/000000000000
10-12 sec.
Femtosecond (f)
Quadrillionth of a second
1/1000000000000000
10-15 sec.