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:
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.
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 nonarithmetic operations on
alphabets and copying at an unbelievable speed.
logical decisions, performing arithmetic and nonarithmetic 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})
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.
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.
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
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.
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.
calculations ‘n’ number of times.
iv] Versatility:
► A computer
is capable of performing a wide variety of functions.
is capable of performing a wide variety of functions.
► It can
accept data and produce results.
accept data and produce results.
► It can
perform the basic arithmetic and logic operations.
perform the basic arithmetic and logic operations.
► It can
transfer data internally
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.
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.
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.
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.
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.
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.
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.
is not intelligent on its own and cannot think its own.
► It can only
perform the tasks specified by the human.
perform the tasks specified by the human.
► It cannot
decide on its own and only the user can determine what the computer must do.
decide on its own and only the user can determine what the computer must do.
► A computer
has no feelings but a human does.
has no feelings but a human does.
Table 1.3:
Measures of capacity
Measures of capacity
Kilo(K)

1 Thousand

= 10^{3} and 2^{10} bytes

Mega(M)

1 Million

= 10^{6} and 2^{20} bytes

Giga(G)

1 Billion

= 10^{9} and 2^{30} bytes

Tera(T)

1 Trillion

=10^{12} and 2^{40} bytes

Peta(P)

1 Quadrillion

=10^{15} and 2^{50} bytes

Bit/Binary
Digit:
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.
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
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.
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 wordsize 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.
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 wordsize 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
= Double word
1024 Bytes

1 Killobyte (KB)

2^{10 }or 10^{3}

1024 KBs

1 Megabyte (MB)

2^{20} or 10^{6}

1024 MBs

1 Gigabyte (GB)

2^{30} or 10^{9}

1024 GBs

1 Terabyte (TB)

2^{40} or 10^{12}

1024 TBs

1 Petabyte (PB)

2^{50} or 10^{15}

1024 PBs

1 Exabyte (EB)

2^{60} or 10^{18}

1024 EBs

1 Zettabyte (ZB)

2^{70} or 10^{21}

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