Networking

There are types of networking available for computer, these are LAN, MAN & 

WAN

1)Local Area Networks (LAN)- 

Networks that optimized for moderate size Geographic area, such as a single office building, a warehouse, or a campus – Low bit error rate and delay

2)Metropolitan Area Networks (MAN)- 

Networks that optimized for a larger geographic area than a LAN, ranging from several blocks of buildings to entire cities – bit error rate and delay LAN

3)Wide Area Networks (WAN)- 

Networks that optimized for connecting equipment separated by long distances, (hundreds or thousands of miles), typically use telephone lines leased from phone companies – high bit error rate and delay. Baseband Vs Broadband

1)Baseband LAN/MANs

- Use digital signaling.

- Signals are inserted on the line as voltage pulses and use the entire frequency spectrum.

 - Bi-directional transmission. 

- Limited distance, ~1km, (due to attenuation.)

2)FDM Broadband LAN/MANs

- Use Analog signaling.

 - Use FDM to divide whole bandwidth into channels.

 - Uni-directional transmission

- Use active amplifier.

KEYBOARD

Back Space:

Used to erase the character or blank space to the left side of the cursor position.

Page Up:

Scroll the page (vertically) upper side of the page.

Space Bar:

Used to the character or blank space to the right side of the cursor position.

Insert:

Used to insert character at the current cursor position.

Print Screen:

Used to print or capture- whatever is displayed on the screen? (Dos)

Tab key:

Use to move the active text cursor at the particular position.

End:

End of the line

HOME:

Beginning of the line.

Computer – Number System

When we type some letters or words, the computer translates them in numbers as computers can understand only numbers.

          A computer can understand positional number system where there are only a few symbols called digits and these symbols represent different values depending on the position they occupy in the number.

A value of each digit in a number can be determined using:

* The digit

* The position of the digit in the number

* The base of the number system (where base is defined as the total number of digits available in the number system).

Decimal Number System

            The number system that we use in our day-to-day life is the decimal number system. Decimal number system has base 10 as it uses 10 digits from 0 to 9. In decimal number system, the successive positions to the left of the decimal point represent units, tens, hundreds, thousands and so on.

          Each position represents a specific power of the base (10). For example, the decimal number 1234 consists of the digit 4 in the units position, 3 in the tens position, 2 in the hundreds position, and 1 in the thousands position, and its value can be written as

(1×1000)+ (2×100) + (3×10) + (4×1)

(1×10³)+ (2×10²) + (3×10¹) + (4×10°)

1000+200+30+4

1234

          As a computer programmer or an IT professional, you should understand the following number systems, which are frequently used in computers.

S.L		Number SYSTEM & Description
1		Binary Number System Base 2. Digits used: 0, 1
2		Octal Number System Base 8. Digits used: 0 to 7
3		Hexa Decimal Number System Base 16. Digits used: 0 to 9, Letters used: A- F

Binary Number System

Characteristics

*        Uses two digits, 0 and 1.

*        Also called base 2 number system.

*        Each position in a binary number represents a 0 power of the base

(2).Example, 2⁰.

*        Last position in a binary number represents a x power of the base

(2). Example, 2˟ where x represents the last position – 1.

Example

Binary Number:

                       

Calculating Decimal Equivalent:

Octal Number System

Characteristics

*        Uses eight digits: 0, 1, 2, 3, 4, 5, 6, 7.

*        Also called base 8 number system.

*        Each position in an octal number represents a 0 power of the base (8).

Example, 80.

Last position in an octal number represents an x power of the base (8).Example, 8x where x represents the last position – 1.

EXAMPLE

Octal Number: 125708

Calculating Decimal Equivalent

Hexadecimal Number System

Characteristics

Uses 10 digits and 6 letters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.

Letters represent numbers starting from 10. A = 10. B = 11, C = 12, D = 13, E = 14, F = 15.

Also called base 16 number system.

Each position in a hexadecimal number represents a 0 power of the base (16).

Example, 160.

Last position in a hexadecimal number represents an x power of the base (16).

Example, 16x where x represents the last position – 1.

EXAMPLE

Hexadecimal Number: 19FDE16

Calculating Decimal Equivalent: