Operating system.

 The Operating System is a program with the following features −

• An operating system is a program that acts as an interface between the software and the computer hardware.

• It is an integrated set of specialized programs used to manage overall resources and operations of the computer.

• It is a specialized software that controls and monitors the execution of all other programs that reside in the computer, including application programs and other system software.

Objectives of Operating System

The objectives of the operating system are −

• To make the computer system convenient to use in an efficient manner.

• To hide the details of the hardware resources from the users.

• To provide users a convenient interface to use the computer system.

  Characteristics of Operating System

  Here is a list of some of the most prominent characteristic features of Operating Systems −

  • Memory Management − Keeps track of the primary memory, i.e. what part of it is in use by whom, what part is not in use, etc. and allocates the memory when a process or program requests it.

  • Processor Management − Allocates the processor (CPU) to a process and deallocates the processor when it is no longer required.

  • Device Management − Keeps track of all the devices. This is also called I/O controller that decides which process gets the device, when, and for how much time.

  • File Management − Allocates and de-allocates the resources and decides who gets the resources.

  • Security − Prevents unauthorized access to programs and data by means of passwords and other similar techniques.

  • Job Accounting − Keeps track of time and resources used by various jobs and/or users.

  • Control Over System Performance − Records delays between the request for a service and from the system.

NETWORKING

 A computer network is a system in which multiple computers are connected to each other to share information and resources.

Characteristics of a Computer Network

• Share resources from one computer to another.

• Create files and store them in one computer, access those files from the other computer(s) connected over the network.Following is the list of hardware's required to set up a computer network.

  • Network Cables
  • Distributors
  • Routers

    Network Cables

    Network cables are used to connect computers. The most commonly used cable is Category 5 cable RJ-45.

    

  Distributors

  A computer can be connected to another one via a serial port but if we need to connect many computers to produce a network, this serial connection will not work.

  Router

  A router is a type of device which acts as the central point among computers and other devices that are a part of the network. It is equipped with holes called ports. 

  
  

  Universal Serial Bus (USB)

  

  USB card is easy to use and connects via USB port. Computers automatically detect USB card and can install the drivers required to support the USB network card automatically.

  
  
  

Data and Information.

 Data can be defined as a representation of facts, concepts, or instructions in a formalized manner, which should be suitable for communication, interpretation, or processing by human or electronic machine.

Data is represented with the help of characters such as alphabets (A-Z, a-z), digits (0-9) or special characters (+,-,/,*,<,>,= etc.)

What is Information?

Information is organized or classified data, which has some meaningful values for the receiver. Information is the processed data on which decisions and actions are based.

For the decision to be meaningful, the processed data must qualify for the following characteristics −

• Timely − Information should be available when required.

• Accuracy − Information should be accurate.

• Completeness − Information should be complete.

Data Processing Cycle

Data processing is the re-structuring or re-ordering of data by people or machine to increase their usefulness and add values for a particular purpose. Data processing consists of the following basic steps - input, processing, and output.

• Input − In this step, the 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 can be recorded on any one of the several types of input medium, such as magnetic disks, tapes, and so on.

• Processing − In this step, the input data is changed to produce data in a more useful form. For example, pay-checks can be calculated from the time cards, or a summary of sales for the month can be calculated from the sales orders.

• Output − At this stage, the result of the proceeding processing step is 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.

Number conservation

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

(1 x 1000)+ (2 x 100)+ (3 x 10)+ (4 x l)
(1 x 103)+ (2 x 102)+ (3 x 101)+ (4 x l00)
1000 + 200 + 30 + 4
1234

S.No.	Number System and 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 of the binary number system are as follows − Uses two digits, 0 and 1 Also called as 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 2x where x represents the last position - 1. Example Binary Number: 101012 Calculating Decimal Equivalent − Step Binary Number Decimal Number Step 1 101012 ((1 x 24) + (0 x 23) + (1 x 22) + (0 x 21) + (1 x 20))10 Step 2 101012 (16 + 0 + 4 + 0 + 1)10 Step 3 101012 2110

Number system of Compuetr

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

The value of each digit in a number can be determined using −

• The digit

• The position of the digit in the numberAs a computer programmer or an IT professional, you should understand the following number systems which are frequently used in computers.

  S.No.	Number System and 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 of the binary number system are as follows − Uses two digits, 0 and 1 Also called as base 2 number systemBinary Number: 101012 Calculating Decimal Equivalent − Step Binary Number Decimal Number Step 1 101012 ((1 x 24) + (0 x 23) + (1 x 22) + (0 x 21) + (1 x 20))10 Step 2 101012 (16 + 0 + 4 + 0 + 1)10 Step 3 101012 2110 Note − 101012 is normally written as 10101. Octal Number System Characteristics of the octal number system are as follows − Uses eight digits, 0,1,2,3,4,5,6,7 Also called as base 8 number system Hexadecimal Number System Characteristics of hexadecimal number system are as follows − Uses 10 digits and 6 letters, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F Letters represent the numbers starting from 10. A = 10. B = 11, C = 12, D = 13, E = 14, F = 15 Also called as base 16 number system Example Hexadecimal Number: 19FDE16 Calculating Decimal Equivalent − Step Binary Number Decimal Number Step 1 19FDE16 ((1 x 164) + (9 x 163) + (F x 162) + (D x 161) + (E x 160))10 Step 2 19FDE16 ((1 x 164) + (9 x 163) + (15 x 162) + (13 x 161) + (14 x 160))10 Step 3 19FDE16 (65536+ 36864 + 3840 + 208 + 14)10 Step 4 19FDE16 10646210

SOFTWARE

 Software is a set of programs, which is designed to perform a well-defined function. A program is a sequence of instructions written to solve a particular problem.

There are two types of software −

• System Software
• Application Software

  System Software

  The system software is a collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software is generally prepared by the computer manufacturers. 

  Some examples of system software are Operating System, Compilers, Interpreter, Assemblers, etc.

  

  Here is a list of some of the most prominent features of a system software −

• Close to the system
• Fast in speed
• Difficult to design
• Difficult to understand

  Application Software

  Application software products are designed to satisfy a particular need of a particular environment.Example.

  • Payroll Software
  • Student Record Software
  • Inventory Management SoftwareFeatures of application software are as follows −
    • Close to the user
    • Easy to design
    • More interactive
    • Slow in speed

HARDWARE

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

Examples of Hardware are the 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

• Hardware and software are mutually dependent on each other. Both of them must work together to make a computer produce a useful output.

• Software cannot be utilized without supporting hardware.

• Hardware without a set of programs to operate upon cannot be utilized and is useless.