Computer information: Computer Hardware

COMPUTER - HARDWARE

Hardware represents the physical and tangible components of the computer, i.e., the components that can be seen and touched.

Examples of Hardware are following:

• Input devices -- keyboard, mouse, etc.
• Output devices -- printer, monitor, etc.
  
• Secondary storage devices -- Hard disk, CD, DVD, etc.
• Internal components -- CPU, motherboard, RAM, etc.

Relationship between Hardware and Software

• Mutually dependent. Both of them must work together to make computer produce a useful output.
• Software cannot be utilized without supporting hardware.
• Hardware without set of programs to operate upon cannot be utilized and is useless.
• To get a particular job done on the computer, relevant software should be loaded into the hardware.
• Hardware is a one time expense.
• Software development is very expensive and is a continuing expense.
• Different softwares can be loaded on a hardware to run different jobs.
• A software acts as an interface between the user and the hardware.
• If hardware is the 'heart' of a computer system, then software is its 'soul'. Both are complimentary to each other.

Computer information: Computer Ports

COMPUTER - PORTS

What is a Port?

• A computer port is a physical docking point using which an external device can be connected to the computer.
• A computer port can also be programmatic docking point through which information flows from a program to computer or over the internet.

Characteristics

• External devices are connected to a computer using cables and ports.
• Ports are slots on the motherboard into which a cable of external device is plugged in.
• Examples of external devices attached via ports are mouse, keyboard, monitor, microphone, speakers, etc.

Following are few important types of ports:

Serial Port

• Used for external modems and older computer mouse.
• Two versions: 9 pin, 25 pin model.
• Data travels at 115 kilobits per second.

Parallel Port

• Used for scanners and printers
• Also called printer port.
• 25 pin model.
• Also known as IEEE 1284-compliant Centronics port.

PS/2 Port

• Used for old computer keyboard and mouse
• Also called mouse port.
• Most of the old computers provide two PS/2 ports, each for mouse and keyboard.
• Also known as IEEE 1284-compliant Centronics port.

Universal Serial Bus (or USB) Port

• Can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard, etc.
• Introduced in 1997.
• Most of the computers provide two USB ports as minimum.
• Data travels at 12 megabits per second.
• USB compliant devices can get power from a USB port.

VGA Port

• Connects monitor to a computer's video card.
• Has 15 holes.
• Similar to serial port connector but serial port connector has pins, it has holes.

Power Connector

• Three-pronged plug
• Connects to the computer's power cable that plugs into a power bar or wall socket.

Firewire Port

• Transfer large amounts of data at very fast speed.
• Connects camcorders and video equipments to the computer
• Data travels at 400 to 800 megabits per second.
• Invented by Apple
• Three variants: 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector and 9-Pin FireWire 800 connector

Modem

• Connects a PC's modem to the telephone network.

Ethernet Port

• Connects to a network and high speed Internet.
• Connects network cable to a computer.
• This port resides on an Ethernet Card.
• Data travels at 10 megabits to 1000 megabits per second depending upon the network bandwidth.

Game Port

• Connect a PC to a joystick.
• Now replaced by USB.

Digital Video Interface, DVI port

• Connects a Flat panel LCD monitor to the computer's high-end video graphic cards.
• Very popular among video card manufacturers.

Sockets

• Connect microphone, speakers to sound card of the computer

Computer Information: Computer-Memory units

COMPUTER - MEMORY UNITS

• It is the amount of data that can be stored in the storage unit.
• The storage capacity are expressed in terms of Bytes.

Following are the main memory storage units:

Sr. No.	Unit	Description
1	Bit (Binary Digit)	A binary digit is logical 0 & 1 representing a passive or an active state of a component in an electric circuit.
2	Nibble	A group of 4 bits is called nibble.
3	Byte	A group of 8 bits is called byte. A byte is the smallest unit, which can represent a data item or a character.
4	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 and 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 the computer words.

Few higher storage units are the following:

Sr. No.	Unit	Description
1	Kilobyte (KB)	1 KB = 1024 Bytes
1	Megabyte (MB)	1 MB = 1024 KB
1	GigaByte (GB)	1 GB = 1024 MB
1	TeraByte (TB)	1 TB = 1024 GB
1	PetaByte (PB)	1 PB = 1024 TB