Computer Fundamentals What is Computer? Computer is an advanced electronic device that takes raw data as input from the user and processes these data under the control of set of instructions (called program) and gives the result (output) and saves output for the future use. It can process both numerical and non-numerical (arithmetic and logical) calculations. Characteristics of Computters 1) Automatic: Given a job, computer can work on it automatically without human interventions 2) Speed: Computer can perform data processing jobs very fast, usually measured in microseconds (10-6), nanoseconds (10-9), and picoseconds (10-12) 3) Accuracy: Accuracy of a computer is consistently high and the degree of its accuracy depends upon its design. Computer errors caused due to incorrect input data or unreliable programs are often referred to as Garbage-In-Garbage-Out (GIGO) 4) Diligence: Computer is free from monotony, tiredness, and lack of concentration. It can continuously work for hours without creating any error and without grumbling 5) Versatility: Computer is capable of performing almost any task, if the task can be reduced to a finite series of logical steps 6) Power of Remembering: Computer can store and recall any amount of information because of its secondary storage capability. It forgets or looses certain information only when it is asked to do so 7) No I.Q.: A computer does only what it is programmed to do. It cannot take its own decision in this regard 8) No Feelings: Computers are devoid of emotions. Their judgment is based on the instructions given to them in the form of programs that are written by us (human beings) A computer has four functions: a. accepts data Input b. processes data Processing c. produces output Output d. stores results Storage Input (Data): Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc. Process: Process is the operation of data as per given instruction. It is totally internal process of the computer system. Output: Output is the processed data given by computer after data processing. Output is also called as Result. We can save these results in the storage devices for the future use. Computer System All of the components of a computer system can be summarized with the simple equations. COMPUTER SYSTEM = HARDWARE + SOFTWARE+ USER • Hardware = Internal Devices + Peripheral Devices All physical parts of the computer (or everything that we can touch) are known as Hardware. • Software = Programs Software gives "intelligence" to the computer. • USER = Person, who operates computer. Generation of computer: In 1822, Charles Babbage built the ‘Difference Engine’. This could do only one kind of calculations. In 1833, Charles Babbage designed and worked on Analytical Engine. It was a general purpose computer designed to solve almost any type of problem. It contained most of the elements we find in modern digital computer systems. Hence, Charles Babbage is considered as Father of modern computer. First Generation (1940-56): The first generation computers used vaccum tubes & machine language was used for giving the instructions. These computer were large in size & their programming was difficult task. The electricity consumption was very high. Some computers of this generation are ENIAC, EDVAC, EDSAC & UNIVAC-1. Second Generation(1956-63): In 2nd generation computers, vaccum tubes were replaced by transistors. They required only 1/10 of power required by tubes. This generation computers generated less heat & were reliable. The first operating system developed in this generation. The Third Generation (1964-71): The 3rd generation computers replaced transistors with Integrated circuit known as chip. From Small scale integrated circuits which had 10 transistors per chip, technology developed to MSI circuits with 100 transistors per chip. These computers were smaller, faster & more reliable. High level languages invented in this generation. The fourth Generation(1972- present): LSI & VLSI were used in this generation. As a result microprocessors came into existence. The computers using this technology known to be Micro Computers. High capacity hard disk were invented. There is great development in data communication. The Fifth Generation (Present & Beyond): Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. ARCHITECTURE OF COMPUTER INPUT DEVICES Input devices accept data and instructions from the user. Following are the examples of various input devices, which are connected to the computer for this purpose. 1. Keyboard 2. Mouse 3. Light Pen 4. Optical/magnetic Scanner 5. Touch Screen 6. Microphone for voice as input 7. Track Ball 1. Keyboard A keyboard is the most common input device. Several kinds of keyboards are available, but they resemble each other with minor variations. Generally standard keyboard has 104 keys. Sr. Keys Description No. These keys include the letter keys (A-Z) and digits 1 Typing Keys keys (0-9) which generally give same layout as that of typewriters. It is used to enter numeric data or cursor movement. Generally, it consists of a set of 17 keys that are laid 2 Numeric Keypad out in the same configuration used by most adding machine and calculators. The twelve functions keys are present on the keyboard. These are arranged in a row along the top 3 Function Keys of the keyboard. Each function key has unique meaning and is used for some specific purpose. These keys provide cursor and screen control. It includes four directional arrow key. Control keys 4 Control keys also include Home, End, Insert, Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt), Escape(Esc). Keyboard also contains some special purpose keys 5 Special Purpose Keys such as Enter, Shift, Caps Lock, Num Lock, Space bar, Tab, and Print Screen. Control keys Left Arrow, Right Arrow, Up Arrow, or Down Arrow Move the cursor or selection one space or line in the direction of the arrow, or scroll a webpage in the direction of the arrow Home Move the cursor to the beginning of a line or move to the top of a webpage End Move the cursor to the end of a line or move to the bottom of a webpage Page Up Move the cursor or page up one screen Page Down Move the cursor or page down one screen Delete Delete the character after the cursor, or the selected text; in Windows, delete the selected item and move it to the Recycle Bin Insert Turn Insert mode off or on. When Insert mode is on, text that you type is inserted at the cursor. When Insert mode is off, text that you type replaces existing characters. Special Purpose Keys Shift Press Shift in combination with a letter to type an uppercase letter. Press Shift in combination with another key to type the symbol shown on the upper part of that key. Caps Lock Press Caps Lock once to type all letters as uppercase. Press Caps Lock again to turn this function off. Your keyboard might have a light indicating whether Caps Lock is on. Tab Press Tab to move the cursor several spaces forward. You can also press Tab to move to the next text box on a form. Enter Press Enter to move the cursor to the beginning of the next line. In a dialog box, press Enter to select the highlighted button. Spacebar Press the Spacebar to move the cursor one space forward. Backspace Press Backspace to delete the character before the cursor, or the selected text. PrtScn (or Print Screen) pressing PrtScn captures an image of your entire screen (a "screen shot") and copies it to the Clipboard in your computer's memory. From there you can paste it (Ctrl+V) into Microsoft Paint or another program and, if you want, print it from that program. ScrLk (or Scroll Lock) pressing these keys causes the document to scroll without changing the position of the cursor or selection. Esc Cancel the current task Application key Open a menu of commands related to a selection in a program. Equivalent to right-clicking the selection. Windows logo key Open the Start menu Pause/Break This key is rarely used. In some older programs, pressing this key pauses the program or, in combination with Ctrl, stops it from running. 2. Mouse A mouse is an electro-mechanical, hand-held device. It is used as a pointer. It can perform functions like selecting menu commands, moving icons, resizing windows, starting programs, and choosing options. The most common mouse uses an internal, magnetically coated ball, to detect the movement of the mouse across a flat surface, usually a desktop. Now a days Optical or laser mouse is used to detect the movement. Generally, it has two buttons called left and right button and scroll bar is present at the mid. Mouse can be used to control the position of cursor on screen, but it cannot be used to enter text into the computer. All windows based applications today are designed to work with a mouse. A mouse is used to replace hard -to-remember key combinations with easier "Point and Click" actions. However, it cannot substitute all keyboard operations. It can be alternative for commands based operations. Light pen 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.