OBJECTIVE
In this topic we would learn various computer parts which are related to computer hardware and we would also learn the details of computer hardware and their main function.We would learn various input and output devices
HARDWARE
Computer hardware is very useful components which we can see and tangible means we can able to touch such components.Computer hardware having three categories:storage,input, and output.
CPU
Central processing unit is the brain of computer.It stores large amount of data.It is main controller which control the operation of all parts of computer
Central processing unit consists of three units
1.Memory or storage unit
2.Control unit
3.ALU (Arithmetic Logic Unit)
1. MEMORY
The data entered by users are stored in Memory or Storage unit.
The two main types of storage devices are memory and disk drives .Computer memory also classified
into two category
1.Primary Memory
2.Secondary Memory
Primary Memory
Primary Memory or Main memory is computer memory which can be accessed by the CPU .It is more expensive.It holds the data or the instructions which the processor currently working on .Primary memory devices are semiconductor memories
Primary memory further classified on two parts
1.RAM(Random Access Memory)
2.ROM(Read only Memory)
1.RAM
It stored the data short term basis as soon as power of the computer turned off it lost all the data so it is called volatile Memory.Data is temporary stored
It also further divided into mainly three parts
a)Static RAM (SRAM)
b)Dynamic RAM (DRAM)
c)Synchronous Dynamic RAM (SDRAM)
2.ROM
ROM is non-volatile memory because data is permanently stored which means when power of the computer turned off data is not lost so it is called Non volatile Memory
It also further divided into mainly Four parts
a)MROM (Masked ROM)
b)PROM (Programmable Read Only Memory)
c)EPROM (Erasable and Programmable Read Only Memory)
d)EEPROM (Electrically Erasable and Programmable Read Only Memory
Secondary Memory
The Processor does not communicate with secondary memory directly so data which are stored in secondary Memory transferred to the primary memory which are then accessed by the processor.Secondary memory devices are less expensive as compared to primary memory devices.Secondary memory is also known as External memory or Auxiliary memory.Secondary memory devices are magnetic and optical memories.
Hard disk Drive : It can store large amounts of information.The disks are of different sizes such as 1G, 10G, 40G, etc.Hard disks are flat, circular plates .It is an electro-mechanical data storage device .
Floppy Disk Drive: It stores less information than hard disk and access speed is also slow.
Now a days very few computer we are using it.
Compact Disk Drive:Compact Disk Drive is used to access the compact disk (CD) but its having slow speed than hard disk in terms of data accessing but can store more data than Hard Disk.In a CD there is a hole at the center which is known as manual eject hole or it is also known as Emergency eject hole .There are three main types of CD this are
Standard manufactured CDs (CD-DA),
CD-R recordable and
CD-RW rewriteable
DVD:DVD stands for Digital Versatile Disk.The storage is much more CD .Compact disk can hold around 700MB data where as DVD can store 5GB data.In case of CD the metal layer or recording layer located top of the disk where as in DVD the metal layer or recording layer located middle of the disk.
FLASH DRIVE :In the flash drive the memory is called flash memory which is nothing but a type of computer chip.It has more memory than floppy disk but can store less data than hard drive.It is very fast compared to CD and DVD.It is light in weight.It is using less power than hard disk drive.
MEMORY CARDS:Memory cards are electronic device which can tore electronic data like photos,movies, games,music, documents, programs and many more.It works like flash drive but it having additional device known as card reader.It is durable and very effective than flash drive.
2.CONTROL UNIT
It i mainly responsible for controlling the data transfer and instructions among the other units.It communicate with input output devices.It does not process any data.It is mainly controlling all the other parts of computer.
3.ALU
Arithmetic Logic Unit(ALU) having two section
1.Arithmetic section which is responsible for arithmetic operation like addition,subtraction,multiplication,division.
2.Logic section :This section perform logical operation like comparing,selecting,matching etc.
INPUT DEVICES
1.KEYBOARD:-It is the input device through which we can type text .It is having around 104 keys.NUMBER KEYS(0-9),LETTER KEYS(A-Z),SPECIAL KEY (SPACE BAR KEY,ENTER KEY,CAPS LOCK KEY,DELETE KEY etc
2.MOUSE :-It is known as pointing devices.It helps to point different things on the computer ,draw and color and play games.It has two buttons and one wheel in center.
3.JOYSTICK:It is used to play computer games.
4.SCANNER:It copies the pictures and text from paper onto the paper.we are commonly used desktop flatbed scanner
5.LIGHT PEN:A light pen is light sensitive input device which can be used as a locator,as stroke input devices .
6.MICROPHONE:-Microphone is an input device which converts sound into signal which is stored into the computer and played back by computer
OUTPUT DEVICES
1.MONITOR : -It is the main part of computer output device looks like television also know as Visual Display Unit (VDU).Its having different sizes.Mainly three types of computer monitor are
1.Cathode Ray Tube(CRT)
2.Liquid Crystal Display(LCD)
3.LED(Light Emitting Diode)
2.PRINTER: A printer is used to print information that you see on the monitor on to the paper.The printed paper is known a hard copy or printout which can be touchable .The information on the computer is called soft copy which is not touchable.
3.PLOTTER:-A Plotters are automated pen,pencil or marker which is used in specialized fields such as drawing, architecture and engineering. It also can create designs such as diagrams, blueprints etc.There are two main types of plotters drum(roller) and flatbed plotters.
BUS
Bus is communication path between two components it can be memory to input output devices ,it can be processor to input output devices.It is same like one passenger moving from one place to another the mode of communication is vehicle this may be BUS(Vehicle) same concept in computer system also.If i want to transfer data from one component to another component i can made it through bus.
If you see the diagram you can see in the center M denotes Memory Connecting with various component diagram it is denotes as C and all this connection is made through communication Bus called BUS
Bus can be classified as
1.Address Bus
2.Data Bus
3.Control Bus
ADDRESS BUS
It carries memory addresses from the processor to other components such as input /output devices,primary storage. etc.
Address Bus is unidirectional means data is flow only one direction.Microprocessor to memory or from memory to input output devices.It is unidirectional because outside device not able to write into microprocessor
DATA BUS
It carries data between the processor and other components.It is bidirectional because data can flow both direction from Memory to input /output devices and from input /output devices to Memory .
CONTROL BUS
Control Bus carries signal from the processor to other components.Control bus carries signal where data need to be transferred at sending time it carries the signal and giving alert to the components i am sending data are you ready? After receiving the data by the component it will sen signal to the memory an conforming yes i am received the data so signal is transmitting both ways it is bidirectional .
So remember that only Address Bus is unidirectional and Data Bus and Control Bus is bidirectional.
