(being continued from 29/08/18)

Computer – 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.
- 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 software applications can be loaded on a hardware to run different jobs.
- A software acts as an interface between the user and the hardware.
- If the hardware is the ‘heart’ of a computer system, then the software is its ‘soul’. Both are complementary to each other.

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. These software products comprise of programs written in low-level languages, which interact with the hardware at a very basic level. System software serves as the interface between the hardware and the end users.

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
- Less interactive
- Smaller in size
- Difficult to manipulate
- Generally written in low-level language

## Application Software

Application software products are designed to satisfy a particular need of a particular environment. All software applications prepared in the computer lab can come under the category of Application software.

Application software may consist of a single program, such as Microsoft’s notepad for writing and editing a simple text. It may also consist of a collection of programs, often called a software package, which work together to accomplish a task, such as a spreadsheet package.

Examples of Application software are the following −

- Payroll Software
- Student Record Software
- Inventory Management Software
- Income Tax Software
- Railways Reservation Software
- Microsoft Office Suite Software
- Microsoft Word
- Microsoft Excel
- Microsoft PowerPoint

Features of application software are as follows −

- Close to the user
- Easy to design
- More interactive
- Slow in speed
- Generally written in high-level language
- Easy to understand
- Easy to manipulate and use
- Bigger in size and requires large storage space

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 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. In decimal number system, the successive positions to the left of the decimal point represent units, tens, hundreds, thousands, and so on.

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 10^{3})+ (2 x 10^{2})+ (3 x 10^{1})+ (4 x l0^{0}) 1000 + 200 + 30 + 4 1234

As 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 SystemBase 2. Digits used : 0, 1 |

2 | Octal Number SystemBase 8. Digits used : 0 to 7 |

3 | Hexa Decimal Number SystemBase 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 2^{0} - Last position in a binary number represents a
**x**power of the base (2). Example 2^{x}where**x**represents the last position – 1.

### Example

Binary Number: 10101_{2}

Calculating Decimal Equivalent −

Step | Binary Number | Decimal Number |
---|---|---|

Step 1 | 10101_{2} | ((1 x 2^{4}) + (0 x 2^{3}) + (1 x 2^{2}) + (0 x 2^{1}) + (1 x 2^{0}))_{10} |

Step 2 | 10101_{2} | (16 + 0 + 4 + 0 + 1)_{10} |

Step 3 | 10101_{2} | 21_{10} |

**Note** − 10101_{2} 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
- Each position in an octal number represents a
**0**power of the base (8). Example 8^{0} - Last position in an octal number represents a
**x**power of the base (8). Example 8^{x}where**x**represents the last position – 1

### Example

Octal Number: 12570_{8}

Calculating Decimal Equivalent −

Step | Octal Number | Decimal Number |
---|---|---|

Step 1 | 12570_{8} | ((1 x 8^{4}) + (2 x 8^{3}) + (5 x 8^{2}) + (7 x 8^{1}) + (0 x 8^{0}))_{10} |

Step 2 | 12570_{8} | (4096 + 1024 + 320 + 56 + 0)_{10} |

Step 3 | 12570_{8} | 5496_{10} |

**Note** − 12570_{8} is normally written as 12570.

## 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
- Each position in a hexadecimal number represents a
**0**power of the base (16). Example, 16^{0} - Last position in a hexadecimal number represents a
**x**power of the base (16). Example 16^{x}where**x**represents the last position – 1

### Example

Hexadecimal Number: 19FDE_{16}

Calculating Decimal Equivalent −

Step | Binary Number | Decimal Number |
---|---|---|

Step 1 | 19FDE_{16} | ((1 x 16^{4}) + (9 x 16^{3}) + (F x 16^{2}) + (D x 16^{1}) + (E x 16^{0}))_{10} |

Step 2 | 19FDE_{16} | ((1 x 16^{4}) + (9 x 16^{3}) + (15 x 16^{2}) + (13 x 16^{1}) + (14 x 16^{0}))_{10} |

Step 3 | 19FDE_{16} | (65536+ 36864 + 3840 + 208 + 14)_{10} |

Step 4 | 19FDE_{16} | 106462_{10} |

**Note** − 19FDE_{16} is normally written as 19FDE.

There are many methods or techniques which can be used to convert numbers from one base to another. In this chapter, we’ll demonstrate the following −

- Decimal to Other Base System
- Other Base System to Decimal
- Other Base System to Non-Decimal
- Shortcut method – Binary to Octal
- Shortcut method – Octal to Binary
- Shortcut method – Binary to Hexadecimal
- Shortcut method – Hexadecimal to Binary

## Decimal to Other Base System

**Step 1** − Divide the decimal number to be converted by the value of the new base.

**Step 2** − Get the remainder from Step 1 as the rightmost digit (least significant digit) of the new base number.

**Step 3** − Divide the quotient of the previous divide by the new base.

**Step 4** − Record the remainder from Step 3 as the next digit (to the left) of the new base number.

Repeat Steps 3 and 4, getting remainders from right to left, until the quotient becomes zero in Step 3.

The last remainder thus obtained will be the Most Significant Digit (MSD) of the new base number.

### Example

Decimal Number: 29_{10}

Calculating Binary Equivalent −

Step | Operation | Result | Remainder |
---|---|---|---|

Step 1 | 29 / 2 | 14 | 1 |

Step 2 | 14 / 2 | 7 | 0 |

Step 3 | 7 / 2 | 3 | 1 |

Step 4 | 3 / 2 | 1 | 1 |

Step 5 | 1 / 2 | 0 | 1 |

As mentioned in Steps 2 and 4, the remainders have to be arranged in the reverse order so that the first remainder becomes the Least Significant Digit (LSD) and the last remainder becomes the Most Significant Digit (MSD).

Decimal Number : 29_{10} = Binary Number : 11101_{2.}

## Other Base System to Decimal System

**Step 1** − Determine the column (positional) value of each digit (this depends on the position of the digit and the base of the number system).

**Step 2** − Multiply the obtained column values (in Step 1) by the digits in the corresponding columns.

**Step 3** − Sum the products calculated in Step 2. The total is the equivalent value in decimal.

### Example

Binary Number: 11101_{2}

Calculating Decimal Equivalent −

Step | Binary Number | Decimal Number |
---|---|---|

Step 1 | 11101_{2} | ((1 x 2^{4}) + (1 x 2^{3}) + (1 x 2^{2}) + (0 x 2^{1}) + (1 x 2^{0}))_{10} |

Step 2 | 11101_{2} | (16 + 8 + 4 + 0 + 1)_{10} |

Step 3 | 11101_{2} | 29_{10} |

Binary Number : 11101_{2} = Decimal Number : 29_{10}

## Other Base System to Non-Decimal System

**Step 1** − Convert the original number to a decimal number (base 10).

**Step 2** − Convert the decimal number so obtained to the new base number.

### Example

Octal Number : 25_{8}

Calculating Binary Equivalent −

### Step 1 – Convert to Decimal

Step | Octal Number | Decimal Number |
---|---|---|

Step 1 | 25_{8} | ((2 x 8^{1}) + (5 x 8^{0}))_{10} |

Step 2 | 25_{8} | (16 + 5)_{10} |

Step 3 | 25_{8} | 21_{10} |

Octal Number : 25_{8} = Decimal Number : 21_{10}

### Step 2 – Convert Decimal to Binary

Step | Operation | Result | Remainder |
---|---|---|---|

Step 1 | 21 / 2 | 10 | 1 |

Step 2 | 10 / 2 | 5 | 0 |

Step 3 | 5 / 2 | 2 | 1 |

Step 4 | 2 / 2 | 1 | 0 |

Step 5 | 1 / 2 | 0 | 1 |

Decimal Number : 21_{10} = Binary Number : 10101_{2}

Octal Number : 25_{8} = Binary Number : 10101_{2}

## Shortcut Method ─ Binary to Octal

**Step 1** − Divide the binary digits into groups of three (starting from the right).

**Step 2** − Convert each group of three binary digits to one octal digit.

### Example

Binary Number : 10101_{2}

Calculating Octal Equivalent −

Step | Binary Number | Octal Number |
---|---|---|

Step 1 | 10101_{2} | 010 101 |

Step 2 | 10101_{2} | 2_{8} 5_{8} |

Step 3 | 10101_{2} | 25_{8} |

Binary Number : 10101_{2} = Octal Number : 25_{8}

## Shortcut Method ─ Octal to Binary

**Step 1** − Convert each octal digit to a 3-digit binary number (the octal digits may be treated as decimal for this conversion).

**Step 2** − Combine all the resulting binary groups (of 3 digits each) into a single binary number.

### Example

Octal Number : 25_{8}

Calculating Binary Equivalent −

Step | Octal Number | Binary Number |
---|---|---|

Step 1 | 25_{8} | 2_{10} 5_{10} |

Step 2 | 25_{8} | 010_{2} 101_{2} |

Step 3 | 25_{8} | 010101_{2} |

Octal Number : 25_{8} = Binary Number : 10101_{2}

## Shortcut Method ─ Binary to Hexadecimal

**Step 1** − Divide the binary digits into groups of four (starting from the right).

**Step 2** − Convert each group of four binary digits to one hexadecimal symbol.

### Example

Binary Number : 10101_{2}

Calculating hexadecimal Equivalent −

Step | Binary Number | Hexadecimal Number |
---|---|---|

Step 1 | 10101_{2} | 0001 0101 |

Step 2 | 10101_{2} | 1_{10} 5_{10} |

Step 3 | 10101_{2} | 15_{16} |

Binary Number : 10101_{2} = Hexadecimal Number : 15_{16}

## Shortcut Method – Hexadecimal to Binary

**Step 1** − Convert each hexadecimal digit to a 4-digit binary number (the hexadecimal digits may be treated as decimal for this conversion).

**Step 2** − Combine all the resulting binary groups (of 4 digits each) into a single binary number.

### Example

Hexadecimal Number : 15_{16}

Calculating Binary Equivalent −

Step | Hexadecimal Number | Binary Number |
---|---|---|

Step 1 | 15_{16} | 1_{10} 5_{10} |

Step 2 | 15_{16} | 0001_{2} 0101_{2} |

Step 3 | 15_{16} | 00010101_{2} |

Hexadecimal Number : 15_{16} = Binary Number : 10101_{2}

**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. These three steps constitute the data processing cycle.

**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.

(TO BE CONTINUED)