TNBEDCSVIP.IN. S.No CONTEND Page No 1. NUMBER SYSTEM AND BASE CONVERSIONS TYPES OF NUMBER SYSTEM 1. Binary Number System:

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1 S.No CONTEND Page No 1. NUMBER SYSTEM AND BASE CONVERSIONS TYPES OF NUMBER SYSTEM 1. Binary Number System: 2. Octal Number System 3. Decimal Number System 4. Hexadecimal Number System 2. DIGITAL LOGIC LOGIC GATES Logic Gates AND, OR, NOT, XOR, NAND, NOR, XNOR Universal Logic Gates NAND, NOR 3. COMPUTERS Characteristics: 1. TYPES OF COMPUTERS 1) Super computers 2) Mainframe computers 3) Mini computers 4) Micro computers 2. TYPES OF OPERATING SYSTEM 1) Single User. 2) Multi User. 3. THE TYPES OF SOFTWARE 4. MEMORY UNIT 1) System Software 2) Application Software 1) Cache Memory 2) Primary Memory/Main Memory 3) Secondary Memory I. RAM-Random Access Memory 1) Static RAM (SRAM) 2) Dynamic RAM (DRAM) II. ROM (Read Only Memory) 1) PROM (Programmable Read Only Memory) 2) EPROM (Erasable and Programmable Read Only Memory) 3) EEPROM (Electrically Erasable and Programmable Read Only Memory)

2 NUMBER SYSTEM AND BASE CONVERSIONS Electronic and Digital systems may use a variety of different number systems, (e.g. Decimal, Hexadecimal, Octal, and Binary). Simply put, a number system is a way to represent numbers. We are used to using the base-10 number system, which is also called decimal. Other common number systems include base-16 (hexadecimal), base-8 (octal), and base-2 (binary) TYPES OF NUMBER SYSTEM 1. Binary Number System: Represents two types of digits 0's and 1's, so the base of number system is 2. Uses two types of electronic pulses, where absence of pulse shows 0 and presence of pulse shows 1. Each binary digit is called as bit. Left-most bit of a number is known as Most Significant Bit (MSB) and right-most bit is known as Least Significant Bit (LSB). Its same for all number system. A group of 4 bit is called as nibble and group of 8 bit is called as byte. Value of digit is determined by the position of digit in the number, where lowest value is for the right-most position and each successive position to the left has a higher place value. Its same for all number system. 2. Octal Number System Represents 8 types of digits from 0 to 7, so the base of number system is 8. It takes exactly three binary digits to represent an octal digit. Binary 000 is same as octal digit 0, binary 001 is same as octal 1, and so on. Insufficient to convert values into bytes(8 bit), so not widely used in computers. 3. Decimal Number System Represents 10 types of digits from 0 to 9, so the base of number system is 10. This is the most familiar number system with everyone. 4. Hexadecimal Number System Represents 16 types of digits from 0 to 9 and alphabets from A to F, so the base of number system is 16. Digits from 10 to 15 are represented as 10-A, 11-B, 12-C, 13-D, 14-E, 15-F. As numeric digits and alphabets are used to represent digits, this number system is also called as alphanumeric number system. More complex number system and widely used in computer system.

3 How to convert a number from one base to another? 1. Decimal to Binary (10.25)10 (10) 10 = (1010) 2 Note: Keep multiplying the fractional part with 2 until decimal part.00 is obtained. (.25)10 = (.01)2 Answer: (10.25)10 = ( )2 2. Binary to Decimal ( ) x x x = = ( )2 = (10.25)10 3. Decimal to Octal (10.25)10 (10)10 = (12)8 Fractional part: 0.25 x 8 = 2.00 Note: Keep multiplying the fractional part with 8 until decimal part.00 is obtained. (.25)10 = (.2)8 Answer: (10.25)10 = (12.2)8 4. Octal to Decimal (12.2)8 1 x x x 8-1 = = (12.2)8 = (10.25)10 5. Hexadecimal and Binary To convert from Hexadecimal to Binary, write the 4-bit binary equivalent of hexadecimal. (3A)16 = ( )2 To convert from Binary to Hexadecimal, group the bits in groups of 4 and write the hex for the 4-bit binary. Add 0's to adjust the groups ( )2 = (3DB)16

4 Logic Gates DIGITAL LOGIC LOGIC GATES AND gate (.) The AND gate gives an output of 1 if both the two inputs are 1, it gives 0 otherwise. OR gate (+) The OR gate gives an output of 1 if either of the two inputs are 1, it gives 0 otherwise. NOT gate ( ) The NOT gate gives an output of 1 input is 0 and vice-versa. XOR gate ( ) The XOR gate gives an output of 1 if either both inputs are different, it gives 0 if they are same. Three more logic gates are obtained if the output of above-mentioned gates is negated. NAND gate ( ) - The NAND gate (negated AND) gives an output of 1 if both inputs are 0, it gives 1 otherwise. NOR gate ( ) - The NOR gate (negated OR) gives an output of 1 if both inputs are 0, it gives 1 otherwise. XNOR gate ( ) - The XNOR gate (negated NOR) gives an output of 1 both inputs are same and 0 if both are different. V.MANIKANDAN. M.Sc., B.Ed., M.Phils., CCNA.

5 V.MANIKANDAN. M.Sc., B.Ed., M.Phils., CCNA.

6 Universal Logic Gates Out of the seven logic gates discussed above, NAND and NOR are also known as universal gates since they can be used to implement any digital circuit without using any other gate. This means that every gate can be created by NAND or NOR gates only. For the XOR gate, NAND and NOR implementation is Implemented Using NAND Implemented using NOR Note For implementing XNOR gate, a single NAND or NOR gate can be added to the above circuits to negate the output of the XOR gate.

7 COMPUTERS Computers are the electronic device which takes input from the user, processes the data and gives the exact output to the user. Computer performs three basic operations Characteristics: Input --Processing ----Output Stored data 1. Speed 2. Accuracy 3. Reliability 4. Storage 5. Automation 6. Versatility 7. Diligence 1. TYPES OF COMPUTERS Types of computers are based upon the purpose, functioning and size of the computer. Accordingly they are classified into four types: 1. Super computers 1. Super computers 2. Mainframe computers 3. Mini computers 4. Micro computers The world first Supercomputer CDC 6600 was released by designed by Seymour Cray. The India first Supercomputer PARAM 8000 (made by C-DAC) Most powerful computers characterized as fastest, very high processing speed and of large data storage.specifically used for complex applications by big organization. Good example is NASA and ISRO uses supercomputers to track and control space discovery. Top 5 Super computers 1. Tianhe-2 China 2. Titan United States 3. Sequoia United States 4. K Computer Japan 5. Mira Unites States

8 2. Mainframe computers Capable of performing high processing speed and data storage but not powerful as super computers.wired in air-conditioned rooms. IBM developed its first mainframe computer, known as the Automatic Sequence Controlled Calculator (ASCC), in It solved addition and multiplication problems in less than six seconds. The main difference between supercomputer and mainframes is that supercomputer has a speed of calculations and mostly used for space scientific and engineering related problems i.e. data crunching while mainframe servers are used for transaction process. Modern mainframes Computers 1. IBM zseries 2. System z9 3. System z10 servers Example: ISP providers use mainframe computers to process information about millions of internet users. 3. Mini computers A minicomputer, or colloquially mini, is a class of smaller computers that was developed in the mid-1960s and sold for much less than mainframe and mid-size computers from IBM and its direct competitors. Less processing speed than mainframe computers. Departments of large company's uses this type of computers. They can handle large database and accounting efficiently. Example: Department of computer monitoring the network traffic of whole company. 4. Micro computers Examples of Minicomputers 1. IBM System/3, 2. Honeywell TI-990 Least powerful type of computers but are the most widely used and growing in the fastest rate.hardware peripherals can be attached easily. Includes Desktop computers, Laptops, tablet pc's, Personal Digital Assistants (PDA) etc. Examples of Minicomputers 1. Note book, 2. Laptop, 3. Desktop, 4. Tower

9 TYPES OF OPERATING SYSTEM There are two types of an operating system: 1. Single User. 2. Multi User. 1. Single User Operating System This operating system can run only one program at a time and hence called single user or single task systems. These systems run on microcomputers only one user is normally in command of the system at any given time. Examples of such type of operating system are DOS-Disk Operating System and Macintosh systems. Types of Single user operating system: 1. MS-DOS (Microsoft Disk Operating System) 2. Windows 95, 98, ME, NT 3. Mac OS Macintosh: Apple Macintosh users, uses menus and icons rather than commands. Icons are small symbols that represent commands. Using mouse input device, the user moves a pointer to a word or icon and enters the selection. This system is slower than command driven system. 2. Multi User Operating System Since large computers such as mainframes. can perform more functions than microcomputers and are more complex, therefore, operating system requires for such a system must be able to run several jobs at one time. Such operating systems are called multi-user operating systems. These operating systems can run two or More computer programs concurrently. Now-a-days multi-user operating systems have been adopted for microcomputers as well. Examples are multi user operation system. UNIX: This operating system is written in C Language, which is a high level language. It is less hardware dependent than the operating system written in low level language. Thus UNIX can easily transport from one system to another. System is surrounded by the shell, which serves as a programming language and as a command

10 language interpreter, reading the user commands and interpreting them as requests to execute certain programs. Around the shell are the utilities such as text processing. ZENIX: is an implementation of UNIX operating system for microcomputers. This type of operating system is gained capital rapid acceptance, because of its multiprogramming capabilities and many useful utilities. Types of Multi user operating system: 1. Windows 2. Linux 3. Mac OS X THE TYPES OF 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. Two types of software 1. System Software 2. Application Software 1. 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. Examples: 1. Operating System 2. Compilers 3. Interpreter 4. Assemblers, etc.

11 2. 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: 1. Payroll Software 2. Student Record Software 3. Inventory Management Software 4. Income Tax Software 5. Railways Reservation Software 6. Microsoft Office Suite Software 7. Microsoft Office, etc. MEMORY UNIT A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in the 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. For example, if the computer has 64k words, then this memory unit has 64 * 1024 = memory locations. The address of these locations varies from 0 to Memory three types 1. Cache Memory Advantages 1. Cache Memory 2. Primary Memory/Main Memory 3. Secondary Memory Cache memory is faster than main memory. It consumes less access time as compared to main memory. It stores the program that can be executed within a short period of time. It stores data for temporary use. V.MANIKANDAN. M.Sc., B.Ed., M.Phils., CCNA.

12 Disadvantages Cache memory has limited capacity. It is very expensive. 2. Primary Memory Characteristics of Main Memory These are semiconductor memories. It is known as the main memory. Usually volatile memory. Data is lost in case power is switched off. It is the working memory of the computer. Faster than secondary memories. A computer cannot run without the primary memory. 3. Secondary Memory Characteristics of Secondary Memory These are magnetic and optical memories. It is known as the backup memory. It is a non-volatile memory. Data is permanently stored even if power is switched off. It is used for storage of data in a computer. Computer may run without the secondary memory. Slower than primary memories. RAM-Random Access Memory RAM (Random Access Memory) is the internal memory of the CPU for storing data, program, and program result. It is a read/write memory which stores data until the machine is working. As soon as the machine is switched off, data is erased. RAM is of two types Static RAM (SRAM) Dynamic RAM (DRAM) V.MANIKANDAN. M.Sc., B.Ed., M.Phils., CCNA.

13 1. Static RAM (SRAM) Characteristic of Static RAM Long life No need to refresh Faster Used as cache memory Large size Expensive High power consumption 4. Dynamic RAM (DRAM) Characteristics of Dynamic RAM Short data lifetime Needs to be refreshed continuously Slower as compared to SRAM Used as RAM Smaller in size Less expensive Less power consumption ROM (Read Only Memory) 1. PROM (Programmable Read Only Memory) 2. EPROM (Erasable and Programmable Read Only Memory) 3. EEPROM (Electrically Erasable and Programmable Read Only Memory) Advantages of ROM Non-volatile in nature Cannot be accidentally changed Cheaper than RAMs Easy to test More reliable than RAMs Static and do not require refreshing Contents are always known and can be verified