SS1 WEEK:10 TOPIC: DATA AND INFORMATION

CONTENT MEANING OF DATA: Raw facts or entity which no meaning has been attached to because it has not been processed is referred to as DATA. Data could be facts about people, places, things and their activities. When data passes through some manipulation activities in order to organize them to be meaningful or to achieve a desired result it is said to be processed the result of the processed data is called INFORMATION. TYPES OF DATA Data can take any of these forms 1. Symbols 2. Alphanumeric 3. Alphabet 4. Numeric Data can be gathered by: 1. counting: using counters 2. Observation of people, activities ,transactions or event 3. Questioner 4. Face to face interviews 5. Form filling. INFORMATION: Information can be defined as any piece of fact, data or news discovered, heard or communicated to anyone verbally, or through writing or through other useful means. DIFFRENCE BETWEEN DATA AND INFORMATION People who conduct market research surveys might ask member of the public to complete a questionnaire about a product or a service. These completed questionnaires form the data. The data must be processed and analyzed in order to prepare a report on the survey. The resulting report is information and maybe be used for decision making. DATA INFORMATION This is a raw fact Data that has been processed in such a way to be meaningful to the person who receive it Data are input into the computer system These are output from the computer system Data is meaningless to the user Information is useful to the user EXAMPLES OF INFORMATION: Advertisement on newspapers relating to vacancy; an experienced accountant needed for immediate employment. For further information, visit our website. www.zebralltd.com The zebra crossing, gives information to the road users to stop for people to cross the busy road. Green light informs the road users to go, red light inform the road users to stop, orange light inform road users to get ready. QUALITIES OF GOOD INFORMATION  It should be complete for its purpose  It should be relevant for its use  It should be sufficient and accurate for its purpose  It should be meaningful to the user  The user should have confidence in it  It volume should be manageable. etc

SS1 WEEK: 9 TOPIC: OUTPIT DEVICES II

CONTENT PRINTER There are three types of computer printers: 1. Inkjet: Inkjet printers spray a jet of special ink on the surface to create an ink under control of electric field. Ink jet is used where the volume of print out is not very large. 2. Dot matrix: A Dot matrix printer has a print head that has a series of steel pins. It uses ink ribbon to create images on surface. 3. LaserJet: uses xerography in line with electronically controlled laser beam to produce characters on the photo conductive surface of rotating drum. EXAMPLES OF PRINTERS 1. Thermal Printers: These are non-impact, they are very slow. They form characters by burning them on specifically treated papers 2. Electrostatic Printer: This form of printers work by charging paper electrically. The paper then passes through a toner solution. Particles of ink adhere to the charged areas of the paper. 3. Dot Matrix Printers: These use a dot matrix printing technique which prints characters as a matrix of dots. Printers can also be categorized by whether the printer heads strikes the paper or not; if it does, the printer is called an impact printer. If not it is a non-impact printer. A non-impact printer is faster because it minimizes the physical movement required during the printing process. NON-IMPACT PRINTERS IMPACT PRINTERS  LaserJet printers  Inkjet printers  Thermal printers  Electro thermal printers  Daisy wheel printers act  Dot matrix printer

SS1 WEEK:8 TOPIC: COMPUTER OUTPUT DEVICES

CONTENT OUTPUT DEVICES: Computer output device is a device that releases the processed data from the computer to either the user or any of the storage devices. There are many devices that produce data in different forms such as audio, Visual and hard copy. Computer output devices are type of peripheral devices connected to a computer, using cables or a wireless network. TYPES OF OUTPUT DEVICE  Printer  Speaker  Headphones  Monitor The Monitor: Monitor is an output device. Monitor is also known as screen, Visual Display Unit, Cathode Ray tube (CRT) or console. A monitor looks like TV screen and it is used for viewing the result of the operation going on. This is the major function of the monitor in the computer system. Data entered into the system is visible on the screen. Although, the data appears on the screen directly, the real fact is that data is sent directly into the system unit which invariably displays the data. What is being displayed is called softcopy. Monitors come in different sizes such as the 12” 13” 16” 21” e.t.c. External features of the Monitor 1. Cathode Ray Tube (CRT): This is the tube that house the console 2. Power Button: Power Toggle is a toggle button used in turning the Monitor on and off 3. Adjustment Control: This Contains features such as brightness, Contrast, Colour, e.t.c 4. Power Cable: It is used to supply electric Power to the monitor. 5. Signal Cable: It is used to transfer electronic signals from the computer through the VGA into the monitor. USES OF THE MONITOR 1. It allows the operator to carry out visual check on what he or she has keyed in 2. It helps operator to input data by producing forms on the screen for filling 3. It gives messages to the operator. TYPES OF MONITOR There are two types of monitor, which are the monochrome and colour/ polychrome monitor. The MONOCHROME monitor displays only one colour. Monochrome cannot be used for windows application. The COLOUR monitor can show graphics and texts with several colours. The different types of colour monitor include; I. Colour Graphics Adapter (CGA) II. Enhanced Graphic Adapter (EGA) III. Video Graphic Adapter (VGA) IV. Super Video Graphic Adapter (SVGA) V. Enhanced Video Graphic Adapter (EVGA) Cathode Ray tube: The most common type of monitor for the office and home is the Cathode Ray Tube. This may be due to their low cost and precision. Flat Panel Monitors: They are commonly used by laptops, Notebooks, palmtops and flat screen Monitors common referred to as LCDS. They are less bulky.

SS1 WEEK:7 TOPIC: COMPUTER INPUT DVICES

CONTENT Sections of the Keyboard: The Keyboard is divided into five sections; I. Alphanumeric keys( Alphabet and Numbers): consist of alphabet (a-z) and numbers (0-9) II. Function keys F1-f12: they are twelve in number f1-F12 and are located horizontally on the first row of the enhanced keyboards. On standard keyboard they are labeled F1-F10 III. Control keys- Del, Ctrl, Esc and alt: These are used in line with other keys to instruct to perform specific task. IV. Cursor –Control and screen movement keys-Arrow, home, end, page up etc.: it allows the user to move cursor to the left, Right, up online and down one line. V. Numeric keypad: these are usually situated at the extreme right hand corner of modern keyboard. They have only numbers. FEATURES OF KEYBOARD: 1. Rollover Capability: The Keyboard has ‘Rollover’ capability, that is, several keys can be pressed almost simultaneously and they will be registered in sequence. They will not jam, Thus increasing the operators input speed. 2. Auto-Repeat Capability: Most of the keys on the keyboard have auto-repeat capability. When a key with this feature is depressed, it will keep on repeating the operation until it is released. USES OF KEYBOARD It is used to: 1. Enter text, numbers and punctuation 2. In the absence of the mouse, it can be used to shutdown the computer system. 3. Ctrl +Alt +Del keys can be used to restart the computer during warm booting. MOUSE Mouse, like the keyboard, is an interface through which we communicate with a computer screen. Mouse is used for drawing as well as potting images. Mice are grouped into two  Optical mouse  Ball track mouse BASIC Mouse functions include Clicking: Pressing and releasing a mouse button quickly at once Double Clicking: Pressing and releasing of Mouse button twice in rapid succession Dragging: Press of a mouse button by holding it down while taking the object away Point: this means to move the mouse pointer so that it touches the item. Functions of the mouse 1. It is used for drawing different kinds of object 2. It is used to select items, menu etc. 3. It is used in moving, cutting and pasting objects. FEATURES OF COMPUTER MOUSE 1. It has right and left button 2. Mouse has scroll button 3. Presence of ball/laser underneath To use the Mouse you need just two fingers; your right thumb and the third finger. Your first finger should be on the left button while the third finger should be on the right. These operations differ from laptops to laptops

SS1 WEEK: 6 TOPIC: COMPUTER INPUT DEVICES

An Input Device is any computer hardware equipment used to feed or send data into the main storage of a computer for processing. Many input devices can be classified into two:  Modality of input( e.g mechanical motion, audio, visual etc)  The input is discrete (keyboard) or continuous (mouse’s position) TYPES OF INPUT DEVICES I. Modern Input Devices a. Camera b. Compact disc (CD) c. Keyboard d. Mouse e. Scanner f. Joystick g. Barcode Scanner h. Microphone i. Etc. II. Earliest Input devices a. Punch Card b. Card Reader c. Punched paper Tape d. Magnetic Tape unit e. Optical Character Recognition f. Etc. THE KEYBOARD: The keyboard is an input device which is used to input data into the computer system. Keyboard remains the most vital interface between the user and the computer. It is the most common input device for entering data into the computer. Keyboard is an electronic device with several groups of keys electronically linked to the processor when attached to a computer system. TYPES OF KEBOARD: There are two main types of keyboard 1. Standard keyboard 2. Enhanced keyboard Features of Standard keyboard I. It has 10 function keys II. It has four arrow keys III. It has 84-89 keys in all Features of Enhanced keyboard I. It has 12 function keys (F1-F12) II. It has 8 arrow keys III. It has 101-105 keys in all

SS1 WEEK:5 TOPIC: HISTORICAL DEVELOPMENT OF COMPUTING DEVICES( 20th Century)

CONTENT These generations of computers witnessed the first set of computers that used vacuum tubes for circuitry and magnetic drum for memory and were very big taking up the whole room. They were very expensive to use and in addition made use of lot of heat. The heat generated often damage the computer. ENIAC: ENIAC (Electronic Numeric Integrator and Computer) was the world’s first general purpose, electronic, digital computer. ENIAC is called general purpose because it can be reconfigured to solve many problems and electronic because it used electronic devices that is the Vacuum tubes. It was invented by John Mauchly and J.Presper Eckert FEATURES OF ENIAC 1. The most important of ENIAC features is that its light speed. It can perform 5000 addition cycles each second 2. It as ability to perform digit discrimination and branch loop 3. ENIAC cannot store programs electronically. Programs must hard wire before machine starts. COMPONENTS OF ENIAC ENIAC contained vacuum tubes, crystal diodes, relays, resistors, capacitors and hand soldered joints. Inputs was possible from an 1Bm, card punch was used for output. USES ENIAC could perform 5,000 simple addition and subtraction. EDVAC: EDVAC (Electronic Discreet Variable Automatic Computer). EDVAC was one of the earliest electronic computers. It was invented by John Mauchly and J.Presper Eckert. FEATURES OF EDVAC 1. It as magnetic tape reader recorder 2. A control unit with oscilloscope 3. A dispatcher unit to receive instructions from the control and memory and directs them to other units 4. A computational unit to perform arithmetic operations on a pair of numbers 5. A timer 6. Three temporary tanks each holding a single word. COMPONENTS OF EDVAC: The computer had vacuum tubes, diodes and consumed 56kw of power. USES OF EDVAC: The EDVAC were used for addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory. UNIVAC: UNIVAC ( Universal Automatic Computer) was the first commercial computer produced in the United States. It was invented by John Mauchly and J.Presper Eckert. It separated the complex problems of input and output from the actual computation facility. FEATURES OF UNIVAC 1. It was the first computer equipped with magnetic tape unit and buffer memory 2. The machine was 25 feet by 50 feet in length COMPONENTS: UNIVAC contained tubes, crystal diodes and relays USES OF UNIVAC: 1. It was used for arithmetic functions, multiplication and division 2. It was used to calculate company payrolls, sales records, analysis of sales performance and other company business. DESKTOP AND PERSONAL COMPUTERS A desktop computer is called a PC; it is used in a particular position unlike a mobile laptop or portable computer. FEATURES OF A PERSONAL COMPUTER: They include a Motherboard, CPU, and RAM, power pack, Monitor, System software, application software, keyboard, Carcass, screen and mouse. COMPONENTS: 1. DIODE 2. Chips 3. Capacitor 4. Resistor 5. Coil 6. Integrated circuit USES: Word processing, spreadsheet application, browsing, internet, digital messaging, multimedia playback, computer game, etc. LAPTOP & NOTEBOOK COMPUTERS A laptop is called a notebook is a personal computer for mobile use. A laptop is powered by electricity via an AC adaptor and can be used away from an outlet using a rechargeable battery. FEATURES OF LAPTOP & NOTEBOOK COMPUTERS: Features include Webcam, Wireless connection, Finger print, Bluetooth, audio jack, card reader, etc. COMPONENTS and USES: Same as desktop components PALMTOP This is another class of portable computer that is handheld. Palmtop have an operating system that is compatible with that of our desktop computer. Palmtop do not have disk drives rather their programs are stored in ROM and are loaded in RAM when they are turned on. A major difference between palmtop and laptop computer is that palmtop are usually powered by off sheet batteries such as a cells. FEATURES: Color screen, expansion slot, wireless capability, voice recorder. COMPONENTS AND USES: Is the same as that of a laptop

SS1 WEEK:4 TOPIC: HISTORICAL DEVELOPMENT OF COMPUTING DEVICES 2 (PRE COMPUTER AGE TO 19TH CENTURY)

CONTENT JACQUARD’S LOOM (FEATURES, COMPONENT AND USES) The Jacquard loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801. This loom simplifies the process of manufacturing textiles with complex patterns such as brocade, damask and matelassé. The loom is controlled by punched cards with punched holes, each row of which corresponds to one row of the design. Multiple rows of holes are punched on each card and the many cards that compose the design of the textile are strung together. CHARLES BABBAGE: Charles Babbage (1791-1871) was born 26 Dec 1791, the son of London banker. Babbage put forward an idea of a machine that could do 60 calculations per second. This analytical engine stamped the foundation of the modern computing. Therefore Babbage is often considered the father of modern computers. On his 200th birth anniversary, 1st of November 1991, the scientist and engineers built the difference Engine No. 2 based on his sound idea in his memory. The Computer Contains the following features 1. Sequential control of arithmetic operation 2. Punched cards which formed a record of the programme or the steps which the engines was to follow. 3. Memory (1000 words of 50 digits) 4. Arithmetic Unit 5. Input 6. Output ANALYTICAL ENGINE (COMPONENT, FEATURES AND USES): The analytical engine, a new kind of mechanical computer that could do complex calculations, including multiplication and division. The basic parts of the analytical engine resemble the components of any computer in the market today. It featured two hallmarks of any modern machine. A CPU and Mill and memory was known as the “store”. Reader to input instructions as well as a way to record, on paper, results generated by the machine. Babbage called the output device a printer, the precursor of ink jet and laser printer so common today. HOLLERITH CENSUS MACHINE: Herman Hollerith’s tabulator consisted of electrically operated components that captured and processed census data by reading holes on paper punch cards. The primary components of the system are 1. Pantograph: used to transfer census information from the census schedules to paper punch cards. 2. Card reader 3. Sorting table: After registering the punch card data on the dials, the sorter specified which drawer the operator places the punch card. BURROUGH’S MACHINES: William Burroughts built his first experimental model of an adding machine with printed output in 1884 Components and features: The distinguishing features are the high sloping keyboard, the beveled glass front, and the printing mechanism out of sight at the rear of the machine. The machine performs additions only, with no provision for subtraction either directly or by addition of complement. There are two large keys on the left-hand side for totals and sub-totals, and three smaller keys for non-add.

SS1: WEEK:3 TOPIC: HISTORICAL DEVELOPMENT OF COMPUTING DEVICES 1(PRE COMPUTER AGE TO 19TH CENTURY)

CONTENT HISTORICAL DEVELOPMENT OF COMPUTING DEVICES: The origin of computers dates back to when our fore fathers used their early calculating devices to count. For example I. Counting with fingers and toes: calculations were done by our fore fathers with their toes and fingers before the invention of computers. II. Counting with pebbles: when counting with fingers became inadequate the early men later introduced pebbles (stone) to count the number of flocks they had. Prior to the invention of alternative means for counting, fingers ,toes ,stones and beads were used in counting in the performance of simple arithmetic calculations such as additions and subtractions etc. This simple way of counting was a difficult to use for large numbers. This early method was in place till the invention of Abacus device. ABACUS DEVICE: The Abacus device was invented to replace the manual method (finger/ stone) of counting. The Abacus dates as far back as 500 B.C. It was invented to make calculations easier and to suit various numbers of system. It was used in China, Greece, and Rome etc. FEATURES AND COMPONENTS OF ABACUS: Abacus generally consists of rectangular wooden frame with horizontal rods. Beads made of stones placed in these rods. COUNTING WITH ABACUS: Counting is done by shifting the beads from one place to another; it is a hand use device for addition and subtraction. The Abacus consists of several columns. Farthest from the right represents ‘ones’; the next one ‘tens’; then hundreds and so on. USES OF ABACUS: Abacus was mainly used for addition and subtraction. SLIDE RULE: The slide rule, also known colloquially in the United States as a slip stick, is a mechanical analog computer. The slide rule is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry, but is not normally used for addition or subtraction. It was invented by William Oughtred. FEATURES AND COMPONENTS: This device makes use of a cursor, which is moved up and down various scales to perform multiplication and division using the principle of logarithms. The device is similar to today’s calculator. USES: The slide rule is used mainly for multiplication and division functions. NAPIERS BONE (features and components): The next significant development after Abacus came in, was when John Napier a Scottish mathematician developed a device having a set of rods made of bone for calculation involving multiplication. USES: The Rods had numbers printed on them in order that these numbers would appear in a multiplication table. To perform a multiplication, individual stripes are arranged in order to represent the number to be multiplied. Napeir’s bone is a type of calculator. PASCAL CALCULATOR: This was invented by Blaise Pascal in the year 1642 when he was only 19 years old. This calculating machine is called Pascaline. Blaise Pascal was a French mathematician. FEATURES AND COMPONENT: This was the first mechanical digital calculator that could perform addition and subtraction on whole numbers. It consists of clogged wheels, gears. It had a system of interlocking rotating cog wheels. Each wheel had ten segments. When one wheel completes a rotation, the next wheel moves one segment. Numbers 0 to 9 are there on the circumference on the top row of eight movable of the wheel. USES: this was the first mechanical digital calculator that could perform addition and subtraction on whole numbers. Pascal calculator is also called Pascaline or the Arithmetique. LEIBNITZ MULTIPLIER (FEATURES AND COMPONENTS): A German Gottfried Von Lebuiz famous mathematician invented Leibuizs multiplier. This is made up of wheel. The machine is about 67 cm (26 inches) long, made of polished brass and steel, mounted in an oak case. USES: Leibuiz multiplier allowed long multiplication and division to be done. The process of multiplication involved repeated addition.

SS1 WEEK:2 TOPIC: COMPUTER HARDWARE AND SOFTWARE

CONTENT Definition of Computer hardware: This refers to the physical units or components which make up the computer configuration. The term hardware refers to the tangible parts of a computer that can be seen and touched. Examples of hardware components: I. Monitor II. Motherboard III. CPU( Central Processing Unit) IV. RAM( Random Access Memory) V. Expansion Cards VI. Power Supply VII. Optical Disk Drive VIII. Hard Disk Drive IX. Keyboard X. Mouse. E.t.c The Computer Hardware is divided into two:  System Unit  Peripheral SYSTEM UNIT: The system unit contains the most vital parts of the computer. The central process unit that does the greatest part of the processing is in the system unit. The system unit includes the motherboard that holds a microprocessor chip or a CPU, memory chips and expansion slots and cards, buses and ports. Peripheral: These are devices that are attached to a computer to make it useable. They perform a specific task or operation. E.g Webcam, printers, mouse etc. peripheral devices can’t work on their own. E.g keyboards, joy sticks etc. Peripheral devices can be grouped into: I. Input peripheral devices  Keyboard  Pointing devices: Mouse  Gaming Devices : Joystick, gamepad  Audio input devices : Microphones II. Output peripheral devices  Printer  Speaker  Headphones  Monitor COMPUTER SOFTWARE: The software refers to the programmes which are processed by the Hardware. A program is a sequence of instruction that is carried out by the Hardware to solve given problems or to perform given tasks. SOFTWARE CAN BE CATEGORIES INTO TWO: SYSTEM SOFTWARE: System software is a type of computer program that is designed to run a computer’s hardware and application programs. If we think of the computer system as a layered model, the system software is the interface between the hardware and user application e.g BIOS( Basic input output system), the BOOT program , Assembler etc. APPLICATION SOFTWARE: These are sets of instructions written by a vendor to perform a specific task. Examples are MS word, skpe, explorer etc

SS1 WEEK:1 TOPI: Revision of last term work

CONTENT A computer is a special multi-purpose electronic device (Machine) that is capable of receiving instruction (data), storing and processing it and giving a desire result as output accurately at an incredibly high speed. The computer as a system is made up of the following: 1. Hardware 2. Software HARDWARE: Refers to the physical units or components, which make up the computer configuration. SOFTWARE: The software refers to the programmes which are processed by the Hardware. A program is a sequence of instruction that is carried out by the Hardware to solve given problems or to perform given tasks. CHARACTERISTICS OF COMPUTER The characteristics of computer are: 1. Computation 2. Programmable 3. Power 4. Speed 5. Storage and Retrieval of information 6. Accuracy 7. Versatility 8. Diligence

SS2 WEEK: 9 TOPIC: ALTERNATIVE LOGIC GATE

CONTENT These are gates that are formed from combination of two logic gates. There are two types of alternative logic gate: NAND GATE A NAND gate is the combination of an AND gate and NOT gate. It operates the same as an AND gate but the output will be opposite. Remember, the NOT gate does not always have to be the output leg; it could be used to invert an input signal also. LOGIC SYMBOL FOR THE “NAND” GATE Notice the circle on output C. TRUTH TABLE FOR THE “NAND” GATE INPUT INPUT OUTPUT A B C 0 0 1 0 1 1 1 0 1 1 1 0 NAND GATE EQUATION The NAND gate operation can also be expressed by a Boolean algebra equation. For a 2 – input NAND gate, the equation is: X = A.B This equation read X equal to A and B NOT, which simply means that the output of the gate is not a logic 1 when A and B inputs are their 1 states. NOR GATE A NOR gate is the combination of both an OR gate and NOT gate. It operates the same as an OR gate, but the output will be the opposite. TRUTH TABLE FOR THE “NOR” GATE INPUT INPUT OUTPUT A B C 0 0 1 0 1 0 1 0 0 1 1 0 NOR GATE EQUATION The NOR gate operation can also be expressed by a Boolean algebra equation. For a 2 – input NAND gate, the equation is: X = A + B The expression is the same as the OR gate with an over bar above the entire portion of the equation representing the input. This equation read X equal to A or B NOT, which simply means that the output of the gate is not a logic 1 when A or B are in their 1 states. USES OF LOGIC GATES Logic gates are in fact the building block of digital electronics, they are formed by the combination of transistors (either BJT or MOSFET) to realise some digital operations like logical OR, NOT, AND etc. Every digital product like computers, mobile phones, calculators, even digital watches contains logical gates. XOR GATE The XOR (exclusive – OR) gate acts in the same way as the logical “either or”. The output is “True” if either but not both, of the inputs are “true”. The output is “false” or if both inputs are “true”. LOGIC SYMBOL FOR “XOR” GATE TRUTH TABLE FOR THE “XOR” GATE INPUT INPUT OUTPUT A B Y 0 0 0 0 1 1 1 0 1 1 1 0 XOR COMPARATOR Comparator is a combinational logic circuit that compares the magnitudes of two binary quantities to determine which one has the greater magnitude. In order word, comparator determines the relationship of two binary quantities. A XOR can be used as basic comparator. As you can see, the only difference between these two symbols is that the XNOR has a circle on its output to indicate that the output is inverted. One of the most common uses for XOR gates is to add two binary numbers. For this operation to work, the XOR gate must be used in combination with an AND gate. To understand how the circuit works, review how binary addition works: 0 + 0 = 0 0 + 1 = 1 1 + 0 = 1 1 + 1 = 10 If you wanted, you could write the results of each of the preceding addition statements by using two binary digits, like this: 0 + 0 = 00 0 + 1 = 01 1 + 0 = 01 1 + 1 = 10 When results are written with two binary digits, as in this example, you can easily see how to use an XOR and an AND circuit in combination to perform binary addition. If you consider just the first binary digit of each result, you’ll notice that it looks just like the truth table for an AND circuit and that the second digit of each result looks just like the truth table for an XOR gate. The adder circuit has two outputs. The first is called the Sum, and the second is called the Carry. The Carry output is important when several adders are used together to add binary numbers that are longer than 1 bit.

SS2 WEEK: 7&8 TOPIC: LOGIC GATE

LOGIC EQUATIONS Aside representing the functioning of a logic gate with truth table and grammatical definition, the use of logic equations can be used not only to represent logic gates and circuits, but also with the usage of some theorems and equivalences, to reduce the number of terms involved, simplifying the equation. In logic equation all Boolean variable involved is assigned a letter or symbol, very similar to the algebraic representation of unknown numerical values using letters. This approach is called Boolean algebra. Symbolic logic uses values, variables and operations; TRUE is represented as 1 while FALSE as 0. Variables are represented by letters and can have one or two values, either 0 or 1. Operations are functions of one or more variables. AND gate equation The AND gate operation can also be expressed by a Boolean algebraic equation. For 2 – input AND gate, the equation is; X = A.B The symbol for AND gate operation is a center dot. It does not mean multiplication. The equation read X equals to A and B, which simply mean that the output of the gate is a logic 1 when A and B inputs are in their 1 states. OR gate equation The Boolean algebraic equation expression is given as; X = A + B The equation read X equals to A or B, which simply mean that the output of the gate is a logic 1 when A or B inputs are in their 1 states. NOT gate equation The NOT gate operation can be expressed by a Boolean algebraic equation as; X = Ᾱ A complement bar is placed over the assigned input letter. The expression is read as X is equal Ᾱ which simply means that the output state is opposite of the logic state applied to the input. USES OF LOGIC GATES Logic gates are in fact the building block of digital electronics, they are formed by the combination of transistors to realise some digital operations (Like Logical OR, AND, NOT). Every digital product like computers, mobile, calculators even digital watches contains logic gates. The use of logic gates can be understood by the following example: the single bit full adder in digital electronics is a logic circuit which perform the logical addition of two single bit binary numbers.

SS2 WEEK:6 TOPIC:LOGIC CIRCUIT I

CONTENT LOGIC GATES A logic gate is an elementary building block of a digital circuit. Most Logic gates have two inputs and one output. At any given moment, every terminal is in one of the two binary condition low (0) or high (1). The logic gate of a terminal can, and generally change often, as the circuit processes data. It processes one or more input signal in a logical fashion. Depending on the input value or voltage, the logic gate will either output a value of ‘1’ for ON or a value of ‘0’ for OFF. There are three basic logic gates: AND, OR and NOT. BINARY CODE Logic gates are digital circuits and they utilize a binary numbering system known as binary code. Binary code is the same language used by computer which uses only 1 or 0 as numbers. INPUTS AND OUTPUTS Gates have two or more inputs, except a NOT gate which has only one input. All gates have only one output. Usually the letters A, B, C and so on are used to label inputs and output. LOGIC SYMBOL OF THE “AND” GATE HOW DOES THE AND GATE WORK? ‘AND’ gates are like two or more switches in series. All the switches have to be closed (ON or value of 1) in order to make the lamp (output) turn on. If all the inputs are not ‘ON’, the output is ‘OFF’. TRUTH TABLE FOR “AND” GATE INPUT INPUT OUTPUT A B C 0 0 0 0 1 0 1 0 0 1 1 1 All the value of the AND gate must be a ‘1’ in order or the output value to be ‘1’. Any other input combination will result in zero. OR GATE An ‘OR’ gate is like two or more switches in parallel. Only one switch need to be closed (ON or value of 1) in order to make the lamp (output C) turn ON with a value of 1. LOGIC SYMBOL FOR “OR” GATE TRUTH TABLE OF “OR” GATE INPUT INPUT OUTPUT A B C 0 0 0 0 1 1 1 0 1 1 1 1 A value of ‘1’ applied to either or both inputs of the OR gate will result in an output value of ‘1’. A value of ‘0’ applied to both inputs will result in an output of ‘0’. NOT GATE NOT gate have only one input and output. It reverses the input signal value. If the input is 1, the output will be 0 and if the input is 0 then the output will be 1. LOGIC SYMBOL FOR “NOT” GATE TRUTH TABLE FOR “NOT” GATE INPUT OUTPUT A C 0 1 1 0 “NOT” gate can be referred as inverter, whatever the input signal is the output is always the opposite.

SS2 WEEK: 5 TOPIC: MEMORY UNIT II

CONTENT Differences between primary and secondary memory Primary storage devices Secondary storage devices 1 These devices are temporary. These devices are permanent. 2 These devices are expensive. These devices are cheaper. 3 These devices are faster, therefore expensive. These devices connect via cables and are slow, therefore cheaper. 4 These devices have less storage capacity. These devices have high storage capacity. 5 These devices refer to RAM, ROM etc. These devices refer to FDD, HDD etc. (a) BIT (Binary digit): It is the smallest possible unit of information. It can be either 0 or 1. (b) NIBBLE : Four bits form one nibble (c) BYTE: It is a unit of information consisting of fixed number of bits. It is a combination of 8 bits (d) CHARACTER: It is represented by one byte. It can be a letter, digit, punctuation mark or special characters. (e) WORD: The combination of 2 bytes or 4 bytes or 8 bytes is a word. The data measurement is as follows: 8 bits - 1 byte 1024 bytes - 1 kilobyte (KB) 1024 KB - 1 Mega Byte (MB) 1024 MB - 1 Giga Byte (GB) 1024 GB - 1 Tetra Byte (TB)

SS 2 WEEK: 4 TOPI: Types of Secondary Storage

CONTENT SECONDARY MEMORY Secondary memory or storage is the non – volatile memory that stored externally from the computer. A secondary – storage medium is usually used for the storage of large amount of data or for permanent or long – time storage of data or programs. It is also used for storing backups. Secondary storage media can be ranked according to the following: (i) Retrieval speed: This is the time it takes to locate and retrieve the stored data. (ii) Size / Storage capacity: This is the ability to store data. Large storage capacity is always desired (iii) Cost per bit of capacity: Low cost is preferred TYPES OF SECONDARY MEMORY (i) Magnetic Disk: This is a Mylar or metallic platter on which electronic data are stored. The data are recorded as tiny invisible magnetic spots on its iron oxide coating. The access time for data stored on a magnetic disk is determined by the seek time i.e. the time required for positioning read/write head over the paper track and search time i.e. the time required or spinning the required data under the head. Once the data have been accessed, they are copied from the disk to the processor for processing. The transfer rate depends on the density of the stored data and rotational speed of the disk. Magnetic Disk came in two categories which are: (a) Fixed disk or Hard disk: It is made from materials such as aluminium instead of Mylar. The input/output device used to transfer data to from a hard disk called dish drive. Hard disk may be permanently installed in a drive or in form of removable disk. Forms of Fixed disk or hard disk 1. Larger permanent sealed metal disk (14 – inch) which is used in larger systems and minicomputer. 2. Larger metal disk in removable cartridges (14 – inch) which is used in mini sized and larger systems. 3. Rigid disks permanently housed in Winchester drives. It comes in 9, 8 and 5¼ inches size. 4. 3½ inch disks currently used in PC’s, servers and small ones in Notebooks and other device. (b) Floppy Disk: These disk are available in three sizes which are: 1. 8 inch portable floppy (flexible) disk. 2. 5¼ inch portable floppy disks. These two diskettes are individually packaged in protective envelopes. 3. Compact floppy disk measuring less than 4 inches in diameter. OPTICAL TECHNOLOGY STORAGE This involves the use of laser beams i.e. highly concentrated beams of light. It comes in form of: (a) Optical laser disk which could be Compact Disk Recordable (CD – R), Compact Disk Rewriteable (CD – RW) or Digital Versatile Disk (DVD) or flash which the data stored in it can be read by CD – ROM drives, CD – RW drives, DVD – ROM drives or DVD – RW drives and Flash drive respectively. (b) DVD drive: A digital versatile Disk (DVD) is very similar to CD, but it has much larger data capacity. A dvd is made up of several layers of plastic totalling about 1.2 millimetres thick. DVD are also of same types as CD along with different formats as explained about CD FLASH DRIVES This tiny device makes it so easy to take your files with you, and even easier to use them when you reach your destination. The plug and play pen drives comes in capacity ranging from 16 mb to 1GB. They are faster and more reliable than floppy disks. Comparison of Memory devices The following table summarizes the characteristics of various kinds of data storage in the storage hierarchy Storage Speed Capacity Relative Costs Permanent? Registers Fastest Lowest Highest No RAM Very Fast Low/moderate High No Floppy Disk Very slow low Low Yes Hard Disk Moderate Very High Very Low Yes

CLASS: SS2 WEEK: 3 TOPIC:Memory Unit

CONTENT Memory is the part of the computer that holds data and instructions for processing. It stores program and instructions or data for only as long as the program they pertain to is in operation. TYPES OF MEMORY a. Primary Memory b. Secondary Memory (a) PRIMARY MEMORY: This is the memory that can be directly accessed by the CPU which constantly interact with it, retrieves data stored therein, goes through instructions and execute them as per the requirement. All the information, data and application are loaded there in uniform manner. Example is RAM (Random Access Memory) which is volatile (temporary) but fast form of memory. Apart from the main large capacity RAM, there are two subs – layers of the primary memory. (i) Processor registers within the processor, which are one of the fastest forms of data storage contain a word of data (usually 32 or 64 bits). (ii) Processor cache, which is meant for enhancing the performance of the computer. It links the fast register to slower main memory. Cache memory loads the duplicated information that is used most actively. It is much faster than the main memory but relatively can store limited data. USES OF PRIMARY MEMORY The primary storage unit is used for the following activities: (i) For input and output operations. (ii) For manipulation of text and calculation operations. (iii) For logical or comparison operations. (iv) For storage and retrieval operations. EXAMPLES OF PRIMARY MEMORY (i) RAM chip provides volatile storage, but as long as it is supplied with power, it needs no special regenerator circuits to retain the stored data. (ii) ROM chip retains the stored data when the power supply is cut. So, unlike RAM chips, ROM chips are not volatile. ROM chip may contain micro program that causes the machine to perform certain operations such as starting the computer. ROM chip only read and it does not accept instruction from the users. Types of ROM (a) Programmable Read Only Memory (PROM): It allows a chip to be programmed by the user for converting critical and lengthy operations into micro programs (b) Erasable Read Only Memory (EROM): It can be erased and reprogrammed. It needs to be removed and expose to ultraviolet light for some time before it can accept any new content. (c) Electrical Erasable and Programmable Read Only Memory (EEPROM): It can be reprogrammed with special electrical pulses. Options RAM ROM Elaboration RANDOM ACCESS MEMORY READ ONLY MEMORY Accessibility In reference with the processor, the information stored in the RAM is easily accessed The processor cannot directly access the information that is stored in the ROM. In order to access the ROM information, first the information will be transferred into the RAM and then it gets executed by the processor Working type Both the read and write operations can be performed over the information that is stored in the RAM The ROM memory only allows the user to read the information. User cannot make any changes to the information Storage RAM memory is only used to store the temporary information ROM memory is used to store permanent information and cannot be deleted. Speed The accessing speed of RAM is faster, it assist the processor to boost up the speed. Speed is slower in comparison with RAM, ROM cannot boost up the processor speed Data preserving Electricity is needed in RAM to flow to preserving information Electricity is not needed in ROM to flow to preserving information. structure The RAM is a chip, which is in the rectangle form and is inserted over the mother board of the computer ROMs are generally the optical drivers, which are made of magnetic tapes. Cost The price of RAMs are comparatively high The price of ROMs are comparatively low Chip size Physically size of RAM chip is larger than ROM chip Physically size of ROM chip is smaller than RAM chip Types The RAM memory is categorized into two types they are the: Statistic RAM (SRAM) and Dynamic RAM (DRAM) The ROM memory is categorized into three types, they are: PROM (Programmable Read Only memory), EPROM (Erasable Programmable Read Only memory) and EEPROM (Electrically Erasable Programmable Read Only memory)

CLASS: SS2 WEEK: 2 TOPIC: Central Processing Unit

CONTENT The main objective of the CPU is to perform mathematical calculations on binary numbers; still there are other goals of using CPU as well. The CPU comprises many hardware components like motherboard and circuits. A central processing unit (CPU) is the hardware within a computer that carries out the instructions of a computer program by performing the basic arithmetical, logical, control, and input/output operations of the system. COMPONENTS OF THE CPU As in the picture above the CPU is made up of the following: I. The control unit II. The ALU (Arithmetic Logic Unit) III. Memory Unit Two typical components of a CPU are the arithmetic logic unit (ALU), which performs arithmetic and logical operations, and the control unit(CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary. The control Unit (CU): The control unit is a component of a computer's central processing unit (CPU) that directs operation of the processor. It tells the computer's memory, arithmetic/logic unit and input and output devices how to respond to a program's instructions. It directs the operation of the other units by providing timing and control signals. All computer resources are managed by the CU (Control Unit). It directs the flow of data between the Central Processing Unit (CPU) and the other devices. In modern computer designs, the control unit is typically an internal part of the CPU with its overall role and operation unchanged. The ALU: An ALU performs basic arithmetic and logic operations. Examples of arithmetic operations are addition, subtraction, multiplication, and division. Examples of logic operations are comparisons of values such as NOT, AND, and OR. The logical operations compare numbers, letters and special characters. The relational operations (=,<,>) are used to describe the comparison operations used by the ALU.

CLASS: SS2 WEEK: 1 TOPIC: Revision on OVERVIEW OF COMPUTER HARDWARE

Computer hardware is the collection of physical elements that constitutes a computer system. Computer hardware refers to the physical parts or components of a computer such the monitor, mouse, keyboard, computer data storage, hard drive disk (HDD), system unit (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that can be touched. In contrast, software is instructions that can be stored and run by hardware. Input and Output Devices An input device is any computer hardware equipment used to send data into the storage of the computer for processing examples are keyboard, Card reader, Mouse,. Scanner, Microphone, Joystick etc Computer output device is a device that releases the processed data from the computer to either the user or any storage devices. Examples are the Monitors, printers , speaker, projector etc.