Fundamentals of Computers

Fundamentals of Computers HLCPE

What is a Computer ? • A computer is a machine that manipulates data according to a set of instructions. • A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations.

Devices that comprise a computer system Monitor (output) Speaker (output) System unit (processor, memory…) Printer (output) Storage devices (CD-RW, Floppy, Hard disk,…) Mouse (input) Scanner (input) Keyboard (input)

What is a Computer ? C P U Input Devices Output Devices

Characteristics of Computers • It responds to a specific set of instructions in a well-defined manner. • It can execute a prerecorded list of instructions (a program). • It can quickly store and retrieve large amounts of data.

Hardware Components • Memory: Enables a computer to store, at least temporarily, data and programs. • Mass Storage Device : Allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives. • Input device: Usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer. • Output device: A display screen, printer, or other device that lets you see what the computer has accomplished. • Central processing unit(CPU): The heart of the computer, this is the component that actually executes instructions.

Types of Computers Computers can be generally classified by size and power as follows • Personal Computer: A small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data. • Workstation: A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.

Types of Computers • Minicomputer: A multi-user computer capable of supporting from 10 to hundreds of users simultaneously. In terms of size and processing capacity, minicomputers lie in between mainframes and microcomputers. The 12-bit PDP-8 minicomputer of the Digital Equipment Corporation was the first successful minicomputer. • Mainframe: A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously. • Supercomputer: An extremely fast computer that can perform hundreds of millions of instructions per second. The highly calculation-intensive tasks can be effectively performed by means of supercomputers. Quantum physics, mechanics, weather forecasting, molecular theory are best studied by means of supercomputers. Their ability of parallel processing and their well-designed memory hierarchy give the supercomputers, large transaction processing powers.

Types of Computers Based on the operational principle (how it functions)of computers, they are categorized as analog computers and hybrid computers. • Analog Computers: -These are almost extinct today. -These are different from a digital computer because an analog computer can perform several mathematical operations simultaneously. It uses continuous variables for mathematical operations and utilizes mechanical or electrical energy. -Operate on continuous data like measuring temp. changes -Faster • Digital Computers: -Work on Discrete data -Process data with accuracy -Business and Scientific computers

Hybrid Computers: • These computers are a combination of both digital and analog computers. In this type of computers, the digital segments perform process control by conversion of analog signals to digital ones. - The digital component normally serves as the controller and provides logical operations, while the analog component normally serves as a solver of differential equations.

Personal Computers Personal computers come in a variety of forms such as desktops, laptops and personal digital assistants. • Desktops: A desktop is intended to be used on a single location. The spare parts of a desktop computer are readily available at relative lower costs. Power consumption is not as critical as that in laptops. Desktops are widely popular for daily use in workplaces and households. • Laptops: Similar in operation to desktops, laptop computers are miniaturized and optimized for mobile use. Laptops run on a single battery or an external adapter that charges the computer batteries. They are enabled with an inbuilt keyboard, touch pad acting as a mouse and a liquid crystal display. Its portability and capacity to operate on battery power have served as a boon for mobile users.

Personal Computers • Personal Digital Assistants (PDAs): It is a handheld computer and popularly known as a palmtop. It has a touch screen and a memory card for storage of data. PDAs can also be effectively used as portable audio players, web browsers and smart phones. Most of them can access the Internet by means of Bluetooth or Wi-Fi communication. • Wearable Computers: A record-setting step in the evolution of computers was the creation of wearable computers. These computers can be worn on the body and are often used in the study of behavior modeling and human health. Military and health professionals have incorporated wearable computers into their daily routine, as a part of such studies. When the users’ hands and sensory organs are engaged in other activities, wearable computers are of great help in tracking human actions. Wearable computers are consistently in operation as they do not have to be turned on and off and are constantly interacting with the user.

Input Devices / Output Devices • I/O is the means by which a computer exchanges information with the outside world. • Devices that provide input or output to the computer are called peripherals. • On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. • Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O.

Input Devices • In computing, a keyboard is an input device, partially modeled after the typewriter keyboard, which uses an arrangement of buttons or keys, which act as mechanical levers or electronic switches. • A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor.

Input Devices • A mouse (plural mouses, mice, or mouse devices) is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. • An input device that utilizes a light-sensitive detector to select objects on a display screen. A light pen is similar to a mouse, except that with a light pen you can move the pointer and select objects on the display screen by directly pointing to the objects with the pen. • Digitizing Tablet-Draw handdraw images, graphics

Input Devices Those based on sensitivity • Light Sensitivity a) Optical Mark Reader b) Optical Character Reader c) Optical Bar Code Reader • Magnetic Sensitivity a) Magnetic Ink Character Reader • Headphones, Web Cameras

Output Devices • Monitor - A monitor or display (sometimes called a visual display unit) is a piece of electrical equipment which displays images generated by devices such as computers. a) Monochrome Monitors - Monochrome monitors have only one color of phosphor (mono = one, chrome = color). All text and graphics are displayed in that color. b) Color Monitor - Color monitors, which display text and graphics in multiple colors through the use of alternating-intensity red, green, and blue phosphors.

Output Devices • A liquid crystal display (LCD) is an electronically-modulated optical device shaped into a thin, flat panel made up of any number of color or monochrome pixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector. It is often used in battery-powered electronic devices because it requires very small amounts of electric power. • LED Screen-An LED display is a video display which uses light-emitting diodes. A LED panel is a small display, or a component of a larger display.

Output Devices • Plotters -A plotter is a vector graphics printing device to print graphical plots, that connects to a computer. There are two types of main plotters. Those are pen plotters and electrostatic plotters. • Printers - Printer is a peripheral which produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form.

Output Devices - Types of Printers DOT Matrix Printer - Type of printer that employs movable print heads with pins or wires that shoot and strike the ribbon placing a dot on the paper with hundreds of dots forming images or text. Inkjet Printer - Printer which forms letters and images on the paper by spraying small streams of quick-drying ink. The ink is stored in a disposable ink cartridge. Laser Printer - Laser printers are Printer that uses laser technology to print images on the paper. The laser recreates the image on a negatively charged drum which will then collect ink that is positively charged to attract to the areas of the image. The Paper is then negatively charged therefore the positively charged ink is attracted to the paper and then is fused onto the paper. Plotters - These printers use a pen to draw the image on the paper

Output Devices – Types of Printers Thermal printer - A printer that uses heated pins to "burn" images onto heat-sensitive paper. The pins are electrically heated and brought into contact with the specially treated paper easily, instead of with great impact. The coating on the paper discolors when heated in this way. These printers, used in calculators and many fax machines, are inexpensive, but produce low-quality, low resolution print. They are however, quiet and fast as they print.

Output Devices • A synthesizer (or synthesiser) is an electronic instrument that is capable of producing a variety of sounds by generating and combining signals of different frequencies. • Speakers

How computers work? • A general purpose computer has four main components: the arithmetic and logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires. • The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU).

Control Unit • The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets (decodes) the program instructions, transforming them into a series of control signals which activate other parts of the computer.Control systems in advanced computers may change the order of some instructions so as to improve performance. • A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.

Arithmetic Logic Unit • The ALU is capable of performing two classes of operations: arithmetic and logic • Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic. • Arithmetic Operations like addition, subtractions,multiplication, division. (Uses all mathematical functions)

Memory • The term memory identifies data storage that comes in the form of chips . Moreover, the term memory is usually used as a shorthand for physicalmemory, which refers to the actual chips capable of holding data. • Every computer comes with a certain amount of physical memory, usually referred to as main memory or RAM. You can think of main memory as an array of boxes, each of which can hold a single byte of information. A computer that has 1 megabyte of memory, therefore, can hold about 1 million bytes (or characters) of information.

Types of Memory • RAM(random-access memory): This is the same as main memory. When used by itself, the term RAM refers to read and write memory; that is, you can both write data into RAM and read data from RAM. Most RAM is volatile, which means that it requires a steady flow of electricity to maintain its contents. As soon as the power is turned off, whatever data was in RAM is lost. • ROM (read-only memory): Computers almost always contain a small amount of read-only memory that holds instructions for starting up the computer. Unlike RAM, ROM cannot be written to.

Types of Memory • PROM(programmable read-only memory): A PROM is a memory chip on which you can store a program. But once the PROM has been used, you cannot wipe it clean and use it to store something else. Like ROMs, PROMs are non-volatile. • EPROM(erasable programmable read-only memory): An EPROM is a special type of PROM that can be erased by exposing it to ultraviolet light. • EEPROM(electrically erasable programmable read-only memory): An EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge.

Fundamentals of Computers