Dear Aspirant,

As you know Computer is very important section to get a good score for LIC AAO Exam 2016.Today we are covering the study material on Computer Fundamentals ,that will help you succeed in the upcoming exam for LIC AAO Exam 2016.

Computer:  A computer is a truly amazing machine  that  performs  a specified  sequence  of  operations  as  per  the  set  of instructions (known as programs) given on a set of data (input) to generate desired information (output ).



A complete computer system consists of four parts:

Hardware: Hardware represents the physical and tangible components of the computer.
Software: Software is a set of electronic instructions consisting of complex codes (Programs) that make the computer perform tasks.
User: The computer operators are known as users.
Data: Consists of raw facts, which the computer stores and reads in the form of numbers.


The following features characterize this electronic machine:

Speed
Accuracy
Storage and Retrieval
Repeated Processing Capabilities
Reliability
Flexibility
Low cost
CPU (Central Processing Unit): CPU is considered as the brain of the computer. It performs all types of data processing operations, stores data, intermediate results and instructions (program).It controls the operation of all parts of computer.

Computer hardware consists of the following components: 

Fig: The relationship between different hardware components

CPU itself has following three components:

ALU (Arithmetic Logic Unit): When the control unit encounters an instruction that involves mathematical calculation or decision/logic, it passes the control to the second component, i.e., the arithmetic logic unit (ALU). The ALU includes a group of registers - memory locations built directly into the CPU - that are used to hold data that are being processed by the current instruction.
Registers: The register is the smallest high-speed storage area in the CPU. All data must be represented in a register before it can be processed.
Control Unit: This unit controls the operations of all parts of computer but does not carry out any actual data processing operations
Primary memory consists of mainly two types of memories:

Random Access Memory (RAM): RAM is the internal memory of the CPU for storing data, program and program result. It is read/write memory which stores data until the machine is working. As soon as the machine is switched off, data is erased.
RAM is volatile,e. data stored in it is lost when we switch off the computer or if there is a power failure. Hence a backup uninterruptible power system (UPS) is often used with computers. RAM is small, both in terms of its physical size and in the amount of data it can hold.
There are mainly three types of RAM available:

Dynamic Random Access Memory (DRAM): A type of physical memory used in most personal computers. The term dynamic indicates that the memory must be constantly refreshed2 (reenergized) or it loses its contents. This type of memory is more economical.
Static Random Access Memory (SRAM): A type of memory that is faster and less volatile than DRAM, but requires more power and is more expensive. The term static is derived from the fact that it does not need to be refreshed like DRAM.
Synchronous Dynamic Random Access Memory (SDRAM): A type of DRAM that can run at much higher clock speeds.
Read Only Memory (ROM): The memory from which we can only read but can not write on it . This type of memory is non-volatile. The information is stored permanently in such memories during manufacture. A ROM, stores such instructions that are required to start a computer. This operation is referred to as bootstrap.

There are mainly four types of ROM available:

MROM (Masked ROM): The very first ROMs were hard-wired devices that contained a pre-programmed set of data or instructions. These kinds of ROMs are known as masked ROMs which are inexpensive.
PROM (Programmable Read only Memory): PROM is read-only memory that can be modified only once by a user. The user buys a blank PROM and enters the desired contents using a PROM program
EPROM (Erasable and Programmable Read Only Memory): The EPROM can be erased by exposing it to ultra-violet light for a duration of up to 40 minutes. Usually, an EPROM eraser achieves this function.
EEPROM (Electrically Erasable and Programmable Read Only Memory): The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. Both erasing and programming take about 4 to 10 ms (milli second).
Memory:

A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in computer where data is to be processed and instructions required for processing are stored. The memory is divided into large number of small parts called cells. Each location or cell has a unique address which varies from zero to memory size minus one.



Cache Memory: It is a very high speed semiconductor memory which can speed up CPU. It acts as a buffer between the CPU and main memory.Memory is primarily of three types

Primary Memory/Main Memory: Primary memory holds only those data and instructions on which computer is currently working. It has limited capacity and data is lost when power is switched off.
Secondary Memory: This type of memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing data/Information permanently.
Secondary Storage (External Storage Devices) : Floppy diskettes, hard disk, tapes and optical disks come under the category of external storage devices or ancillary storage devices. These devices are very sensitive to environmental conditions (humidity and temperature) as well as to external magnetic fields and need to be stored carefully.

Floppy Disk : Floppy disks are primarily used on PCs. Information on a floppy disk is recorded in the magnetized states of particles of iron oxides evenly placed upon concentric circles known as tracks.
Hard Disk: It is a non-removable enclosed magnetic disk included in most PCs. It contains a stack of metal platters, each coated with iron oxide, that spin on a spindle and the entire unit is encased in a sealed chamber.
Magnetic Tape: This is plastic tape, usually made of Mylar that is coated with iron oxide, thereby enabling the introduction (writing); retention (memory) and reading of magnetically recorded information. The best use of tape storage is for data that you do not use very often.
Peripherals: Peripheral devices are devices connected to the computer externally. If a peripheral device is disconnected, the computer will still be able to work; only functions performed by this peripheral device will not be available.

Mainly there are following types of peripheral devices:

Input Devices (How to tell it what to do): This unit makes link between user and computer. The input devices translate the information into the form understandable by computer.

Keyboard- The most common and very popular input device which helps in inputting data to the computer
Mouse- Mouse is the most popular pointing device and cursor-control device having a small palm size box with a round ball at its base which senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed.
Joy Stick- To move cursor position on a monitor screen. It is mainly used in Computer Aided Designing (CAD) and playing computer games.
Light pen- It is used to select a displayed menu item or draw pictures on the monitor screen.
Track Ball- Mostly used in notebook or laptop computer, instead of a mouse .This is a ball which is half inserted and by moving fingers on ball, pointer can be moved
Scanner- A scanner allows you to scan printed material and convert it into a file format that may be used within the PC.
Digitizer- It converts analog information into digital form.
Microphone-Microphone is an input device to input sound that is then stored in digital form.
Magnetic Ink Card Reader (MICR)- MICR input device is generally used in banks because of a large number of check to be processed every day.
Optical Character Reader (OCR)- OCR scans text optically character by character, converts
Output Devices: (How it shows you what it is doing) Output devices translate the computer's output into the form understandable by users.

Monitors: Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer. It forms images from tiny dots, called pixels that are arranged in a rectangular form. The sharpness of the image depends upon the number of pixels.

There are two kinds of viewing screen used for monitors.

Cathode-Ray Tube (CRT): The CRT display is made up of small picture elements called pixels. The smaller the pixels, the better the image clarity, or resolution
Flat- Panel Display: The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the CRT.
Printer: Printer is an output device, which is used to print information on paper.

Impact Printers: The impact printers print the characters by striking them on the ribbon which is then pressed on the paper.
Non-Impact Printers: Non-impact printers print the characters without using ribbon. These printers print a complete page at a time so they are also called as Page Printers. Laser Printers, Inkjet Printers.
These three steps constitute the data processing cycle.

Input -Input data is prepared in some convenient form for processing. The form will depend on the processing machine. For example, when electronic computers are used, the input data could be recorded on any one of several types of input medium, such as magnetic disks, tapes and so on.
Processing - In this step input data is changed to produce data in a more useful form. For example, paychecks may be calculated from the time cards, or a summary of sales for the month may be calculated from the sales orders.
Output - The result of the proceeding processing step are collected. The particular form of the output data depends on the use of the data. For example, output data may be pay-checks for employees.
Language Processors:

Assembler: This language processor converts the program written in assembly language into machine language.
Interpreter: This language processor converts a HLL(High Level Language) program into machine language by converting and executing it line by line.
Compiler:-It also converts the HLL program into machine language but the conversion manner is different. It converts the entire HLL program in one go, and reports all the errors of the program along with the line numbers.
Software

Software represents the set of programs that govern the operation of a computer system and make the hardware run.



There are two types of software

System Software: The system software is collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software are generally prepared by computer manufactures. System software serves as the interface between hardware and the end users.
Examples: Operating System, Compilers, Interpreter, Assembler etc.
Application Software: It is the set of programs necessary to carry out operations for a specified application.
Application software can subdivide into three categories:
(A) Packages:-



(B) Utilities: Utilities are those application programs that assists the computer by performing housekeeping functions like backing up disk or scanning viruses etc.



(C) Customized Software:  This type of software is tailor-made software according to a user’s requirements.

Boot: When computer starts, the operating system is first loaded (as it is essential for running all other programs), this process is known as booting.

Cold Boot: -When you turn the computer ON from an OFF position.

Warm Boot: - When you reset the computer that is already ON.

Motherboard: The motherboard serves as a single platform to connect all of the parts of a computer together. A motherboard connects CPU, memory, hard drives, optical drives, video card, sound card, and other ports and expansion cards directly or via cables. It can be considered as the backbone of a computer.

Analog computers

Analog computers always take input in form of signals.
The input data is not a number infect a physical quantity like temp., pressure, speed, velocity.
Signals are continuous of (0 to 10 V).
Accuracy 1% Approximately.
Example: Speedometer.
Digital Computers

These computers take the input in the form of digits & alphabets & converted it into binary format.
Digital computers are high speed, programmable electronic devices.
Signals are two level of (0 for low/off , 1 for high/on).
Accuracy unlimited.
Examples: Computer used for the purpose of business and education are also example of digital computers.
Hybrid Computer

The combination of features of analog and digital computer is called Hybrid computer.

The main examples are central national defense and passenger flight radar system.
They are also used to control robots.
Super Computer

The biggest in size.
Most Expensive
It can process trillions of instructions in seconds.
This computer is not used as a PC in a home neither by a student in a college.
Used by Govt. for different calculations and heavy jobs.
Supercomputers are used for the heavy stuff like weather maps, construction of atom bombs, earthquake prediction etc.
Mainframes

It can also process millions of instruction per second.
It can handle processing of many users at a time.
Less expensive than Supercomputer
It is commonly used in Hospitals, Air Reservation Companies as it can retrieve data on huge basis.
This is normally too expensive and out of reach from a salary-based person.
It can cost up to thousands of Dollars.
Mini Computer

These computers are preferred mostly by small type of business personals, colleges etc.
These computers are cheaper than above two.
Its an intermediary between microcomputer and mainframe.
Micro Computer/ Personal Computer

It is mostly preferred by Home Users.
Cost is less compared to above.
Small in size.
A microcomputer contains a (a central processing unit on a microchip), in the form of read-only memory and random access memory, and a housed in a unit that is usually called a motherboard .
Notebook Computers

Notebook computers typically weigh less than 6 pounds and are small enough to fit easily in a briefcase.
Principal difference between a notebook computer and a personal computer is the display screen.
Many notebook display screens are limited to VGA resolution
Boot: When computer starts, the operating system is first loaded (as it is essential for running all other programs), this process is known as booting.

Cold Boot: -When you turn the computer ON from an OFF position.

Warm Boot: - When you reset the computer that is already ON.

Software categories

Freeware: Software which is completely costless .The produce