Generations of Computers PDF

Diploma in IT – ICTC – Wayamba University of Sri Lanka Generations of Computers ENIAC was amongst the first computing system designed in the 1940s. In size, it was equal to the size of 3-4 double decker buses. With over 18,000 buzzing electronic switches called vacuum tubes it was no where close i...

Diploma in IT – ICTC – Wayamba University of Sri Lanka Generations of Computers ENIAC was amongst the first computing system designed in the 1940s. In size, it was equal to the size of 3-4 double decker buses. With over 18,000 buzzing electronic switches called vacuum tubes it was no where close in computing abilities as compared to a Laptop in the modern times. You must be wondering, how we were able to squeeze down all the electronic circuits into smaller and smaller packages to the modern design where laptops are mere fraction of inches thick and very lightweight. The invention of Integrated Circuits in 1958 made it all possible. First Generation (Mid 1940's ) Computers were using Vacuum tubes (Valves) as an electronic component. Machine language was used. Input was given through punch cards, paper tapes and results in the form of printouts. Computers were as big as room in size. Cost was very high. Second Generation (1956) Vacuum tubes were replaced by the transistors. Size of transistors was much smaller than vacuum tubes. Assembly language was used. Consumed less power, faster and reliable. Size of computers were came down. Price of computers were also reduced. 1 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Third Generation (1964) Integrated Circuits(IC's) made up of small crystal of silicon semiconductor were used. Structured programming language C and COBOL was used. Speed and efficiency were increased. Inputs were given through keyboards and output through monitors. Size of computers, power consumption, heat generation and cost were decreased in greater extent. Fourth Generation (1971 and present) Microprocessor chip were used, made up of thousands of Integrated Circuits build on a single silicon chip. Object oriented programming language and domain specific language SQL for database access. High processing speed, high reliability and low power consumption. Size and cost of computers were cut down. Fifth Generation (Present and future) Computers those are dealing with Artificial Intelligence (AI), expert systems and robotics are in 5th generation. These computers are still in development phase. 2 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Block Diagram of Computer Computer Block Diagram System: Mainly computer system consists of three parts, that are central processing unit (CPU), Input Devices, and Output Devices. The Central Processing Unit (CPU) is divided into two parts again: arithmetic logic unit (ALU) and the control unit (CU). The set of instruction is in the form of raw data. A large amount of data is stored in the computer memory with the help of primary and secondary storage devices. The CPU is like the heart/brain of the computer. The user does not get the desired output, without the necessary option taken by the CPU. The Central processing unit (CPU) is responsible for the processing of all the instructions which are given by the user to the computer system. The data is entered through input devices such as the keyboard, mouse, etc. This set of instruction is processed by the CPU after getting the input by the user, and then the computer system produces the output. The computer can show the output with the help of output devices to the user, such as monitor, printer, etc. Central Processing Unit (CPU) The computer system is nothing without the Central processing Unit so, it is also known as the brain or heat of computer. The CPU is an electronic hardware device which can perform different types of operations such as arithmetic and logical operation. The CPU contains two parts: the arithmetic logic unit and control unit. We have discussed briefly the arithmetic unit, logical unit, and control unit which are given below: Control Unit The control unit (CU) controls all the activities or operations which are performed inside the computer system. It receives instructions or information directly from the main memory of the computer. 1 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka When the control unit receives an instruction set or information, it converts the instruction set to control signals then; these signals are sent to the central processor for further processing. The control unit understands which operation to execute, accurately, and in which order. Arithmetic and Logical Unit The arithmetic and logical unit is the combinational digital electronic circuit that can perform arithmetic operations on integer binary numbers.It presents the arithmetic and logical operation. The outputs of ALU will change asynchronously in response to the input. The basic arithmetic and bitwise logic functions are supported by ALU. Storage Unit The information or set of guidelines are stored in the storage unit of the computer system. The storage unit provides the space to store the data or instruction of processed data. The information or data is saved or hold in computer memory or storage device. The data storage is the core function and fundamental of the computer components. Primary Memory (Main Memory) The Random Access Memory is the main memory of the computer system, which is known as RAM. The main memory can store the operating system software, application software, and other information. The Ram is one of the fastest memory, and it allows the data to be readable and writeable. Secondary memory We can store the data and programs on a long-term basis in the secondary memory. The hard disks and the optical disks are the common secondary devices. It is slow and cheap memory as compare to primary memory. This memory is not connected to the processor directly. It has a large capacity to store the data. The hard disk has a capacity of 500 gigabytes. The data and programs on the hard disk are organized into files, and the file is the collection of data on the disk. The secondary storage is direct access by the CPU; that’s why it is different from the primary storage. The hard disk is about 100 times the capacity of the main memory. The main difference between primary and secondary storage is speed and capacity. There are several large blocks of data which are copied from the hard disk into the main memory. Input Devices The user provides the set of instruction or information to the computer system with the help of input devices such as the keyboard, mouse, scanner, etc. The data representation to the computer system is in the form of binary language after that the processor processes the converted data. The input unit implements the data which is instructed by the user to the system. We can enter the data from the outside world into the primary storage as the input through input devices. The input devices are the medium of communication between the outside world and the computer system. 2 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka There are some important features of input devices which are given below: 1. The input devices receive or accept the data or instruction from the user, who exist in the outside world. 2. These devices convert the data or instruction into the machine-readable form for further processing. 3. The input device performs like the connection between the outside world and our computer system. 4. The keyboard and mouse are common examples of input devices. 5. When the whole procedure is finished, we get the desired output from the output devices such as monitor, printer, etc. Output Devices The output devices produce or generate the desired result according to our input, such as a printer, monitor, etc. These devices convert the data into a human-readable form from binary code. The computer system is linked or connected to the outside world with the help of output devices. The primary examples of output devices are a printer, projector, etc. These devices have various features which are given below: 1. These devices receive or accept the data in the binary form. 2. The output devices convert the binary code into the human-readable form. 3. These devices produce the converted result and show to the user. Central Processing Unit The CPU is an electronic device based on microchip technology; hence it is also often called the microprocessor. It is truly the showcase and culmination of the state-of-the-art in the electronics industry: a tiny silicon-based chip occupying less than 1 square cm contains several millions of transistor elements, measuring less than a thousandth of a millimeter across. They operate at speeds way beyond our comprehension: a typical CPU can multiply more 7-digit numbers in one second than a human could do in ten lifetimes, but uses less energy than a light bulb! 3 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Control unit The CU provides several functions: it fetches, decodes and executes instructions it issues control signals that control hardware it moves data around the system Arithmetic logic unit The ALU has two main functions: It performs arithmetic and logical operations (decisions). The ALU is where calculations are done and where decisions are made. It acts as a gateway between primary memory and secondary storage. Data transferred between them passes through the ALU. ALU performs all the mathematical and logical operations Basic Logical Operations 4 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Registers Registers are small amounts of high-speed memory contained within the CPU. They are used by the processor to store small amounts of data that are needed during processing, such as: the address of the next instruction to be executed the current instruction being decoded the results of calculations Different processors have different numbers of registers for different purposes, but most have some, or all, of the following: program counter - This register is responsible for keeping the address of the next command in the main memory to be processed memory address register (MAR) - This register is used for maintaining the address of all requested items which is going to be written to or read from memory. memory data register (MDR) - When the data is received in the memory buffer register, then it is stored in this register until it is changed. current instruction register (CIR) - Holds the instruction currently being executed or decoded accumulator (ACC) - Holds an intermediate value in mathematical and logical calculations Cache Cache is a small amount of high-speed random access memory (RAM) built directly within the processor. It is used to temporarily hold data and instructions that the processor is likely to reuse. This allows for faster processing as the processor does not have to wait for the data and instructions to be fetched from the RAM. Clock The CPU contains a clock which is used to coordinate all of the computer's components. The clock sends out a regular electrical pulse which synchronises (keeps in time) all the components. The frequency of the pulses is known as the clock speed. Clock speed is measured in hertz. The higher the frequency, the more instructions can be performed in any given moment of time. In the 1980s, processors commonly ran at a rate of between 3 megahertz (MHz) to 5 MHz, which is 3 million to 5 million pulses or cycles per second. Today, processors commonly run at a rate of 3 gigahertz (GHz) to 5 GHz, which is 3 billion to 5 billion pulses or cycles per second. 5 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Speed of processing One can measure the speed of the CPU by checking the time it takes to process one single instruction. The typical CPU is very fast and instruction can be done in about two billionths of a second. To deal with these small fractions of time, scientists have devised smaller units: a millisecond (a thousandth of a second), a microsecond (a millionth), a nanosecond (a billionth) and a picosecond (a trillionth). However, instead of indicating the time it takes to execute a single instruction, the processing speed is usually indicated by how many instructions (or computations) a CPU can execute in a second. This is exactly the inverse of the previous measure; e.g. if the average instruction takes two billionths of a second (2 nanoseconds) then the CPU can execute 500 million instructions per second (or one divided by 2 billionths). The CPU is then said to operate at 500 MIPS or 500 million of instructions per second. In the world of personal computers, one commonly refers to the rate at which the CPU can process the simplest instruction (i.e. the clock rate). The CPU is then rated at 500 MHz (megahertz) where mega indicates million and Hertz means “times or cycles per second”. For powerful computers, such as workstations, mainframes and supercomputers, a more complex instruction is used as the basis for speed measurements, namely the so-called floating-point operation. Their speed is therefore measured in megaflops (million of floating-point operations per second) or, in the case of very fast computers, teraflops (billions of flops). In practice, the speed of a processor is dictated by four different elements: the “clock speed”, which indicates how many simple instructions can be executed per second; the word length, which is the number of bits that can be processed by the CPU at any one time (64 for a Pentium IV chip); the bus width, which determines the number of bits that can be moved simultaneously in or out of the CPU; and then the physical design of the chip, in terms of the layout of its individual transistors. The latest Pentium processor has a clock speed of about 4 GHz and contains well over 100 million transistors. 6 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Parallel CPU Architecture The traditional model of the computer has one single CPU to process all the data. This is called the Von Neumann architecture because he engineered this approach to computers in the days when computers were still a dream. Except for entry-level personal computers, most computers now have two, four, or up to sixteen CPUs sharing the main processing load, plus various support processors to handle maths processing, communications, disk I/O, graphics or signal processing. In fact many CPU chips now contain multiple “cores” each representing an individual CPU. Machine Cycle A machine cycle consists of the steps that a computer’s processor executes whenever it receives a machine language instruction. It is the most basic CPU operation, and modern CPUs are able to perform millions of machine cycles per second. The cycle consists of three standard steps: fetch, decode and execute. In some cases, store is also incorporated into the cycle. The steps of a machine cycle are: Fetch – The control unit requests instructions from the main memory that is stored at a memory’s location as indicated by the program counter (also known as the instruction counter). 7 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Decode – Received instructions are decoded in the instruction register. This involves breaking the operand field into its components based on the instruction’s operation code (opcode). Execute – This involves the instruction’s opcode as it specifies the CPU operation required. The program counter indicates the instruction sequence for computer. These instructions are arranged into the instructions register and as each are executed, it increments the program counter so that the next instruction is stored in memory. Appropriate circuitry is then activated to perform the requested task. Store - The result generated by the operation is stored in the main memory How to mount the CPU in the mother board Computer - Motherboard The motherboard serves as a single platform to connect all of the parts of a computer together. It connects the CPU, memory, hard drives, optical drives, video card, sound card, and other ports and expansion cards directly or via cables. It can be considered as the backbone of a computer 8 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka 9 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Motherboard Bus Structure 10 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Address Bus The address bus is used by the CPU to send the address of the memory location or the input/output port that is to be accessed at the instant. It is a unidirectional bus i.e. the address can be transferred in one direction only and that is form CPU to the required port or location. Whether it is a read operation or write operation the CPU calculates the address of the required data and sends it on the data bus for the execution of the required operation. The maximum number of memory locations that can be accessed in a system is determined by the number of lines of an address bus. Data Bus A data bus is used to carry the data and instructions from the CPU to memory and peripheral devices and vice versa. Thus it is a bidirectional bus. It is one of most important parts of the connections to the CPU because every program instruction and every byte of data must travel across the bus at some point. The size of the data bus is measured in bits. The data bus size has much influence on the computer architecture because the important parameters of it like word size, the quantum of data etc. are determined and manipulated by the size of the data bus. Control Bus A control bus contains various individual lines carrying synchronizing signals that are used to control. Various peripheral devices connected to the CPU. The common signals that are transferred to the control bus from CPU to devices and vice versa are memory read, memory writes, I/O read, I/O write etc. Signals are designed, keeping in mind, the design philosophy of the microprocessor and the requirement of the various devices connected to the CPU. So different types of the microprocessor have different control signals. Computer Input Devices Keyboard A keyboard is one of the primary input devices used with a computer. Similar to an electric typewriter, a keyboard is composed of buttons used to create letters, numbers, and symbols, and perform additional functions. The following sections provide more in-depth information and answers to some of the frequently asked questions about the keyboard. The following image shows a 104-key Saitek keyboard with arrows pointing to each section, including the control keys, function keys, LED indicators, wrist pad, arrow keys, and keypad. 11 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka QWERTY Keyboard Layout Alternatively referred to as the Sholes keyboard, the QWERTY keyboard was invented by Christopher Sholes, who was issued a patent for a typewriter on July 14, 1868. The QWERTY keyboard is named after the first five alphabetic letter keys on the top row keys and is the official computer keyboard standard Today, most desktop computer keyboards connect to the computer using either USB or Bluetooth for wireless communication. Before USB, a computer used PS/2, serial port, or AT (Din5) as a keyboard interface. 12 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Computer mouse A computer mouse is a handheld hardware input device that controls a cursor in a GUI (graphical user interface) and can move and select text, icons, files, and folders on your computer. For desktop computers, the mouse is placed on a flat surface (e.g., mouse pad or desk) in front of your computer. The picture is an example of a Logitech desktop computer mouse with two primary buttons and a wheel. What are the uses of a mouse? Below is a list of all the computer mouse functions and options to give you an idea of all the mouse capabilities. Move the mouse cursor - The primary function is to move the mouse pointer on the screen. Point - Once the mouse is moved, you can point something out for another user or point a digital object. For example, in a game you can use the mouse to point a gun in the direction to shoot. Open or execute a program - Once you've moved the pointer to an icon, folder, or another object clicking or double-clicking that object opens the document or executes the program. Some programs even support tripple-clicking. Select - A mouse also allows you to select text or a file or highlight and select multiple files at once. Drag-and-drop - Once something is selected, it can also be moved using the drag-and-drop method. 13 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Hover - Moving the mouse cursor over objects with hover information helps discover each object's function. Scroll - When working with a long document or viewing a long web page, you may need to scroll up or down. To scroll, rotate the mouse wheel, or click-and-drag the scroll bar. The mouse wheel can also be used as a button. See the IntelliMouse page for further information and functions of the mouse wheel. Touchpad Touchpad is an input device on laptops and some keyboards. It allows the user to move a cursor with their finger. It can be used in place of an external mouse. Scanner When referring to hardware, a scanner or optical scanner is a hardware input device that optically "reads" and image and converts it into a digital signal. For example, a scanner may be used to convert a printed picture, drawing, or document (hard copy) into a digital file which can be edited on a computer. There are also other types of scanners that can be used with a computer. Card scanner - designed to scan business cards. Drum scanner - rotates scanned page around a drum for faster scanning. Handheld scanner - scans text and images by dragging the device over the page you want to scan. Pen scanner - a device slightly larger than a pen you'd write with that can be dragged over text to scan it into a computer. Sheetfed scanner - scans paper by feeding it into the scanner. Card scanner Drum scanner 14 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Handheld scanner Pen scanner Sheetfed scanner Light pen A light pen is a light-sensitive pointing input device commonly used to select or otherwise modify text or data on a screen. Used with a CRT monitor, these devices were an early form of manipulating and highlighting data on the screen. Digital camera A digital camera is a hardware device that takes photographs and stores the image as data on a memory card. Unlike an analog camera, which exposes film chemicals to light, a digital camera uses digital optical components to register the intensity and color of light, and converts it into pixel data. Many digital cameras are capable of recording video in addition to taking photos. Webcam A webcam is a camera that connects to a computer. It captures either still pictures or motion video, and with the aid of software, can transmit its video on the Internet in real-time. 15 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Touch screen A touch screen is a display device that allows the user to interact with a computer using their finger or stylus. They're a useful alternative to a mouse or keyboard for navigating a GUI (graphical user interface). Touch screens are used on a variety of devices, such as a computer and laptop displays, smartphones, tablets, cash registers, and information kiosks. Some touch screens use a grid of infrared beams to sense the presence of a finger instead of utilizing touch-sensitive input. Capacitive Touch Screen A capacitive touch screen is coated with a special material that stores an electrical charge that is monitored by circuits at each corner of the screen. When you touch a capacitive touch screen, a small amount of the electrical charge is drawn from the point of contact to indicate where you touched the screen. To use a capacitive screen, you must use your bare finger or a specially designed capacitive stylus. Most users experience this type of screen technology when attempting to use a smartphone touch screen while wearing gloves and being unable to do anything. Resistive Touch Screen A resistive touch screen is coated with a metallic electrically conductive and resistive layer that detects the pressure of your finger or another object. This technology is often a more affordable solution compared to capacitive, but can be damaged by sharp objects touching the screen. 16 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Surface acoustic wave A SAW (surface acoustic wave) or surface wave touch screen sends ultrasonic waves and detects when the screen is touched by registering changes in the waves. This technology is more advanced than the other two, but does not work with hard materials, and can be affected by outside elements. Magnetic card reader A magnetic card reader is a device that retrieves information from a magnetic card physically near to or swiped through it. The picture shows a good example of a card reader you may see at retail stores. Graphic Tablet It is also called Digitizer; the graphic tablet is an input device basically used for converting hand drawing art into images. The artist draws with the assistance of a stylus on the tablet same as they draw on the paper sheet. The drawing is displayed on the screen of the pc, where it will be edited or saved within the computer. Graphic tablets offer more prominent control and suppleness for specialists by permitting them to determine their drawing to show on their screen as they create it. 17 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Microphone Microphone is an input device to input sound that is then stored in a digital form Other Input Technologies Voice Recognition Voice or speaker recognition is the ability of a machine or program to receive and interpret dictation or to understand and carry out spoken commands. Voice recognition has gained prominence and use with the rise of AI and intelligent assistants. Voice recognition systems enable consumers to interact with technology simply by speaking to it. Gesture Acquisition Technologies 18 Akila Jayasanka Diploma in IT – ICTC – Wayamba University of Sri Lanka Examples of acquisition devices for gesture recognition: (a) left: mobile phone with GPD and accelerometer, right: inertial sensors with accelerometer and gyroscope are attached to a suit worn by Andy Serkis to create the CGI character of Gollum in The Lord of the Rings movies, (b) Google Glass for “egocentric” computing, (c) thermal imagery for action recognition, (d) audio-RGB-depth device (e) active glove and (f) passive glove. Gesture recognition relies upon the integration of several elements. The first stage is to ‘acquire’ the gesture; to capture human movement in a way that it can be processed. Gesture acquisition can be achieved utilizing systems that are device-based (A glove controller worn by a user for example) or systems that are vision-based which use a particular type of camera. Visual input systems can employ various different technologies, including 3D or depth sensing, thermal imaging or RGB. The field of computerized hand-gesture recognition was launched in the early 1980s with the creation of wired gloves with integrated sensors on the finger joints, known as data gloves. At the same time, visual image-based recognition systems were being developed that were based on reading color panels connected to gloves. Brain Controlled Inputs With input sent by the brain and which is then collected by the EGG sensor, interpreted, and sent to the PC, the user should theoretically be able to work on a computer just like they’d do it with another input method. 19 Akila Jayasanka