Perfect Computer Notes

Topic: What are Different Pointing Input Devices  A Pointing input device is an input device which is used to control  the movement of the pointer to select items on a display screen. Examples of pointing input devices include: Mouse, Track ball, Joystick, Pointing Stick, Graphic Tablet, Touch pad or Track pad, Touch Screen and Light pen etc. 1. Mouse Explain different Pointing input devices - Mouse Mouse is an input device used to control motion of pointer on screen. A mouse has two or three buttons called Left, Right and Middle button. Buttons are used to perform different functions. 2. Track Ball   Track Ball is an input device like a mouse. It is used in Lap top computers to control motion of pointer on screen. It is a pointing device like upside down mouse. It has a ball on its upper side. This ball is moved by fingers or thumb and the pointer moves accordingly on screen. 3. Joystick   Joystick is an input device used to play games on c

Topic: Explain different types of storage devices in Computer systems Storage Devices Storage devices are used to store data and instructions permanently. Storage devices are also called secondary storage devices / backing storage devices / external storage devices or auxiliary storage devices. Examples of storage devices include Hard Disk, CD and DVD etc. Why Secondary Storage Devices are Used? Secondary storage devices are used because: Primary memory(RAM) is volatile and temporary. When computer is switched off, all data in ram is erased. Storage devices can store large amounts of data and instructions permanently whereas Primary memory has less capacity of storing data. Types Of Storage Devices There are three main types of storage devices:  Magnetic Tape   Magnetic Disk   Optical Disk   Flash Memory storage devices 1. Magnetic Tape Magnetic tape is the oldest storage device. It is made of plastic coated with magnetic material. Data is stored on mag

We have already discussed the topics: 1. What is RAM, Explain Different Types of RAM 2. What is ROM Explain Different Types of ROM Here we discuss differences between RAM and ROM 13 Differences Between RAM and ROM Thirteen Differences Between RAM and ROM Sr # RAM ROM 1 RAM stands for Random Access Memory ROM stands for Read Only Memory. 2 RAM is a temporary memory. ROM is a permanent memory. 3 RAM is a volatile memory. ROM is a non volatile memory. 4 When computer is turned off, all data and programs are erased from RAM.  When computer is turned off, all data and programs are retained in ROM. 5 RAM is a Read / Write memory. Data can be read and written to RAM. ROM is a read only memory. Data from ROM only can be read and not written. 6 Data and programs in RAM can be changed. The contents of ROM cannot be changed. 7 Data or

Topic:  What is ROM Explain Different Types of ROM ROM ROM stands for Read Only Memory , because its contents can be read and used only and we cannot change or delete its contents. It is a non volatile memory. Its retains its contents even after switching off the computer. Therefore, ROM does not require electricity to retain its contents. ROM is a permanent memory. The instructions in ROM are written at the time of manufacturing by the manufacturer.   Importance of ROM in Computer System 1. One important reason a computer needs ROM is that instructions stored in ROM (called ROM BIOS - Basic Input/Output System)execute on start-up of computer and guide the computer what to do. They make the computer ready for work. 2. ROM contains a set of start-up instructions to check that memory is functioning well and check for other hardware devices. 3. These instructions also check for an operating system and load its necessary part into RAM, so that a user interface for example &quo

Today we are going to discuss Different Types of RAM, that is, Random Access Memory . RAM    /     What does RAM mean Ram stands for Random Access Memory . Data in RAM can be accessed directly. That is, we can access data directly from any location of RAM in the same time. This Random Access quality makes RAM a very fast memory. RAM is volatile. Data and programs in RAM are erased when computer is turned off. What does  RAM  do Therefore RAM is a temporary memory. It is used to store those data and programs, which are currently being executed by CPU. Ram is also called Primary Memory or Main Memory. Where RAM memory chip is installed? RAM chip is installed into one of the memory slots on motherboard, as shown in the figure: What does RAM mean Importance of RAM. 1.  A Program must be laoded in RAM for execution. The programs and data currently being executed are in computer's main memory, that is, in RAM. The programs and data needed by these pro

The devices that can be used to perform both functions -input and output- are called Dual Devices. These devices are also called Dual Purpose Devices or Both Input/Output Devices. With the help of a dual purpose device, we can enter data into computer as well as we can output data from the computer to outside world.  For example, Dual devices include:  Touch Screen Monitor, Modem, Network Interface Card, Sound card, Hard disk drive, Floppy disk Drive, Magnetic Tape Drive CD-Writer and DVD-Writer etc. These are also called Input/output devices, because they perform both functions. Touch Screen Monitor Dual Devices or Both Input / Output Devices - Touch screens Touch Screen Monitor is an input/output device. It uses a special touch sensitive screen. The User can enter data by touching icons or menus on the screen. As soon as the user selects a command from menu, output is displayed on screen. Commonly touch screen monitors use sensors to detect touch of finger.    

CENTRAL PROCESSING UNIT / CPU / Microprocessor / Processor Central processing unit is the brain of computer. It is also called CPU or processor . Processor is used to process data according to given instructions. It performs arithmetic and logical operations on data. Parts / Components of CPU / Processor on computergap.com It controls all activities of different parts of a computer . As brain in human body controls all other parts of body and takes decisions, CPU controls all other parts of the computer and their working. A CPU has three basic parts: Arithmetic Logic unit, Control unit and Registers. Parts of Microprocessor or Processor or CPU or Central Processing Unit computergap.com 1.    ARITHMETIC LOGIC UNIT (ALU) ALU performs data processing according to given instructions. All computations are done in this unit. ALU is the real place in computer where actual execution of instructions takes place. ALU may be further categorized into two sections acco