CHAPTER-1-IT.docx

**Chapter 1: COMPUTER APPRECIATION** **COMPUTER** - Balagurusamy (2009), electronic machine that takes input from the user, processes the given input and generates output in the form of useful information. - accepts input in different forms such as data, programs and user reply....

**Chapter 1: COMPUTER APPRECIATION** **COMPUTER** - Balagurusamy (2009), electronic machine that takes input from the user, processes the given input and generates output in the form of useful information. - accepts input in different forms such as data, programs and user reply. - known as data processing unit,data processor and data processing system. - (Shelly et al., 2011), electronic device operating under the control of instructions stored in its own memory, that can accept data, process the data according to specified rules, produce results, and store the results for future use. **Data** - raw details that need to be processed to generate some useful information. **Programs** - set of instructions that can be executed by the computer in sequential or non-sequential manner. **User reply** - input provided by the user in response to a question asked by the computer. **Information Processing Cycle** - happens when computers process data (input) into information (output). - series of input, process, output, and storage activities - communications also has become an essential element of this - Data\> Capture Data\> Manipulate Data\> Output Results\> Information **Software** - collection of related instructions organized for a common purpose is referred to as software. **CHARACTERISTICS OF COMPUTER** **Speed** - can solve large and complex problems in few seconds. - generally depends upon its hardware configuration. **Storage capacity** - can store huge amount of data in its different storage components in many different formats. - [storage area] of a computer system is generally divided into [two categories]: main memory and secondary storage. **Accuracy** - carries out calculations with great accuracy. - depends upon its hardware configuration and the instructions. **Reliability** - produces results with no error. - most of the errors generated in the computer are human errors that are created by the user itself. **Versatility** - can perform many different tasks and can be used for many different purposes. **Diligence** - can perform repetitive calculations any number of times with the same accuracy. - do not suffer from human traits, such as tiredness,fatigue,lack of concentration,etc. **Garbage-In,Garbage-Out (GIGO)** - limitation of computers since they are capable of doing only what they are instructed output. **INPUT UNIT AND ITS FUNCTIONS** **Input Unit** - used to enter the data into the computer **Functions:** 1\. It accepts (or reads) instructions and data from outside world 2\. It converts these instructions and data in computer acceptable form 3\. It supplies the converted instructions and data to the computer system for further processing **OUTPUT UNIT AND ITS FUNCTIONS** **Output Unit** - used to display the information generated by the computer to the user **Functions:** 1. It accepts the results produced by the computer, which are in coded form and hence,cannot be easily understood by us 2. It converts these coded results to human acceptable (readable) form 3. It supplies the converted results to outside world **STORAGE UNIT AND ITS FUNCTIONS** 1. Data and instructions required for processing (received from input devices) 2. Intermediate results of processing 3. Final results of processing, before they are released to an output device There are two types of storage: **1. Primary Storage/Main Memory (RAM or Random Access Memory)** ·Used to hold running program instructions ·Fast in operation ·Small Capacity ·Expensive ·Volatile (loses data on power dissipation) **2.Secondary storage (ROM)** ·Used to hold stored program instructions ·Used to hold data and information of stored jobs ·Slower than primary storage ·Large Capacity ·Lot cheaper that primary storage ·Retains data even without power **CENTRAL PROCESSING UNIT (CPU) AND COMPUTER SYSTEM** **central processing unit (CPU)** - where function of any computer system revolves around this central component - popularly referred to as the \"brain\" of the computer - responsible for processing the data inside the computer system and for controlling all other components of the system (Balagurusamy, 2009). - "Processor" The main operations of the CPU include four phases: 1\. Fetching Instructions from the memory. 2\. Decoding the instructions to decide what operations to be performed. 3\. Executing the instructions. 4\. Storing the results back in the memory. ALU + CU= CPU Two Subsystems of a Central Processing Unit 1\. **Arithmetic Logic Unit** - place where the actual executions of instructions take place during processing operation. - **Arithmetic Unit (AU)-** part of CPU that performs arithmetic operations\* on the data \*can be addition, subtraction, multiplication or division **2. Control Unit** - manages and coordinates the operations of all other components of the computer system - important component of CPU that controls the flow of data and information. - maintains the sequence of operations being performed by the CPU. **COMPUTER SYSTEM** A system has following three characteristics: 1. A system has more than one element 2\. All elements of a system are logically related 3\. All elements of a system are controlled in a manner to achieve the system goal A computer is a system as it comprises of integrated components (input unit,output unit, storage unit, and CPU) that work together to perform the steps caled for in the executing program (Sinha P.K. et al, 2008). Five basic operations of a computer system: **Inputting** - entering data and instructions into the computer system **Storing** - saving data and instructions to make them readily available for initial or additional processing whenever required **Processing** - performing arithmetic operations (add, subtract, multiply,divide,etc.) on data to convert them into useful information **Outputting** - producing useful information or results for the user such as a printed report or visual display **Controlling** - directing the manner and sequence in which all of the above operations are performed. **NUMBER SYSTEM** Balagurusamy (2009) on Computer Systems and Binary Codes 1\. Introduction to Computer Systems \- Definition: A computer is a digital system. \- Function: Stores and processes different types of data using binary form (0s and 1s). 2\. Types of Data Handled by Computers \- Numbers \- Alphabets \- Special characters 3\. Need for Data Conversion \- User-entered data needs to be converted into a form the computer can process. \- Data is transformed into a format understandable by the system. 4\. Development of Binary Codes \- Different codes developed to represent data in binary format. \- Binary system uses 0s and 1s to represent each type of data. 5\. Binary Codes and Computer Processing \- Conversion into binary form is essential for processing. \- Computer codes are also known as binary codes because they convert data into binary form. - a number system in which numbers are represented using some symbols called **digits** and the values of these numbers can be determined by taking the position of digits into consideration. Four different number systems 1\. Decimal system 2\. Binary system 3\. Octal system 4\. Hexadecimal system **DECIMAL SYSTEM** - most common number system used by human beings. - also known as base10 number system. - have 10 symbols or digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Hence, its base=10 - we use this number system in our day-to-day life **BINARY SYSTEM** - most dominant number system that is employed by almost all the modern digital computer systems. - also known as base-2 system - using this, computer systems can store and process each type of data in terms of Os and 1s only. The following are some of the technical terms used in binary system: 1. **Bit** - smallest unit of information used in a computer system. - can either have the value 0 or 1. - derived from the words *B*inary dig*IT*. 2. **Nibble** - combination of 4 bits. 3. **Byte** - 8 bits. - derived from words \'by eight\'. 4. **Word** - 16 bits. 5. **Double word** - 32 bits. 6. **Kilobyte (KB)** - used to represent the 1024 bytes of information. 7. **Megabyte (MB)** - 1024 KBs of information. 8. **Gigabyte (GB)** - 1024 MBs of information. **OCTAL SYSTEM** - uses base 8 to represent different values - eight symbols (digits 0 to 7) are available for representing the values in this system **HEXADECIMAL SYSTEM** - uses base 16 to represent different values - symbols are the digits 0-9 and the letters A, B, C, D, E and F. The digits 0-9 are used to represent the decimal values 0 through 9 and the letters A, B, C,D,E and F are used to represent the decimal values 10 through 15 **COMPUTER CODES** - used for internal representation of data in computers. - In binary coding, every symbol that appears in the data is **Byte** - commonly used computer codes are **BCD, EBCDIC,** and **ASCII**. **ASCII CODE** - Pronounced as ASKEE and is used for the same purpose for which the EBCDIC code is used but is more famous - Initially, this was 7-bit BCD code to handle 128 characters but later modified to an 8-bit code. **ASCIl**- American Standard Code for Information Interchange Two types: **1. ASCII-7** - uses 7 bits to represent a symbol and can represent 128 (27) different characters **2. ASCII-8** - 8 bits to represent a symbol and can represent 256 (28) different characters Note:**First 128 characters** in ASCII-7 and ASCII-8 are **same**. **UNICODE** - 16-bit Unicode is an International 16-bit character set that contains a maximum of 216= 65,536 different characters - Sufficient to represent almost all the technical and special symbols used by the major languages of the world - Encodes the different characters by assigning them to a unique value (referred as **code point)** - Allows computer to deal with almost all the characters belonging to different languages used in the world. **Encoding Forms** - UTF-8, UTF-16,UTF-32 - The 16-bit Unicode is a character code that is supported by almost all the operating systems such as MS Windows, Linux and Mac OS X. - MS Windows operating system allows the use of all the Unicode characters through an accessory called **Character Map**.