Computer organization

1. Computer organization Generic computer contains: • Input devices: keyboard, mouse, A/D (analog-to-digital) converter etc. • Computational unit: (computer's heart) central processing unit (CPU), • a memory, and an input/output (I/O) interface Organization of a Simple Computer • Output devices: Monitors, printers, D/A converters Aim: • Familiar with the components of a computer system • Helps to understand what an operating system is ! • OS- which it facilitates the execution of programs

2. Central processing unit (CPU) • Executes program, instruction • It is single electronic component processor CPU parts • Control unit: Tells rest of the computer, how to carry • out a program’s instruction • It directs the movement of electronic signals between memory • Arithmetic-Logic unit (ALU): Perform operations • (arithmetic and logical) • Mathematical:Sub, Div, Add, Multiply • Logical: Comparisons of data

3. Computer memory (data storage) • Computer data storage provides one • of the core functions that of information • retention Types of memory: • Primarymemory usually refers to a form of semiconductor storage known as Random access memory (RAM), It is fast but temporary storage, Volatile memory Read only memory (ROM), nonvolatile memory E.g. BIOS Cache memory High speed, expensive, used to store instruction temporarily • Secondarystorage today more commonly refers to mass storage - optical discs, forms of magnetic storage like hard disks

4. Hierarchy of storage hard disk drive with protective cover removed | • Tertiary storage • third level of storage, involves a robotic mechanism which will mount (insert) and dismount removable mass storage media into a storage device according to the system's demands • Off-line storage • device that physically • removed or disconnected

5. I/p & O/p units An Input device is any piece of computer hardware equipment used to provide data and control signals to an information processing system (such as a computer). E.g. Microphone An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world. E.g. LCD projector Note: Input and output devices make up the hardware interface between a computer and the user or external world.

6. Input Device Basic organization of a computer. T O U C H P A D Mouse • In computing, a mouse (plural mice, mouse devices, or • mouses) is a pointing device that functions by detecting • two-dimensional motion relative to its supporting surface. • Physically, a mouse consists of a small case, held under • one of the user's hands, with one or more buttons • The mouse's motiontypically translates into the motion • of a pointer on a display, which allows for fine control of • a Graphical User Interface.

7. A keyboard is a peripheral that physically an arrangement of buttons, or keys. • A keyboard typically has characters engraved or printed on the keys • Physically, a keyboard is an arrangement of buttons, or keys • A keyboard typically has characters engraved or printed on • the keys; in most cases, each press of a key corresponds to • a single written symbol.

8. Joystick • Joystick elements: • Stick 2. Base • 3. Trigger 4. Extra buttons • 5. Autofire switch 6. Throttle • 7. Hat Switch (POV Hat) 8. Suction Cup • A joystick is an input device consisting of a stick that pivots • on a base and reports its angle or direction to the device it is • controlling. • Joysticks are often used to control video games, and usually • have one or more push-buttons whose state can also be read • by the computer. • A popular variation of the joystick used on modern • video game consoles is the analog stick. • Three-dimensional clockwise and anti clockmovement is there

9. a scanner is a device that optically • scans images, printed text, handwriting, • or an object, and converts it to a digital image. • 3D scanners used for industrial design, • reverse engineering, test and • measurement, orthotics, gaming • and other applications. Image Types of scanner rotary scanner :used for high-speed document scanning planetaryscanner: used for takeing photographs of books and documents 3D scanners, for producing three-dimensional models of objects

10. Digitizingordigitization is representing • an object, image, document or a signal • (usually an analog signal) by a discrete set • of its points or samples. The result is called • "digital representation" or, more specifically, • a "digital image", for the object, and • "digital form", for the signal. • A Tablet PC is a notebook or slate- • shaped mobile computer, equipped with • a touch screen or graphics tablet/screen • hybrid technology which allows the user • to operate the computer with a stylus or • digital pen, or a fingertip, instead of a • keyboard or mouse.

11. Output Device • Visual display unit: A visual display unit • (also called VDU,monitor, or screen) • offers a two-dimensional visual presentation • of information. • Speaker: A speaker can be used for various • sounds meant to alert the user, as well as • music and spoken text. • Printer: Printers produce a permanent hard copy of the information on paper or A printer is an output device that produces text and graphics on paper. Types: • impact printer:produces text and images • when tiny wire pins on print head strike the • ink ribbon by physically contacting the paper • E.g. dot-matrix printer • non-impact printer: E.g. inkjet, laser and thermal printer

12. OMR (Optical mark recognition) • The process of capturing data by contrasting • reflectivity at predetermined positions on a • page. By shining a beam of light onto the document the Scanner is able to detect a • marked area because it reflects less light than • an unmarked surface. • One of the applications of optical mark • recognition is the use of #2 (HB in Europe) • pencil bubble optical answer sheets in multiple • choice question examinations. • Another example of OMR is the recognition of • scannable bar codes in various product

13. Optical Mark Recognition (OMR): • OMR technology detects the presence or absence of a mark, but not the shape of the mark. Forms containing small ovals, referred to as bubbles that are filled in by a respondent, are scanned through an OMR Scanner. OMR can not recognize the hand-printed or machine printed characters. • OMR is the fastest and most accurate data collection • techniques. For test answers, and grid like ID numbers, • it's also easy for the user. • The accuracy of OMR is a result of precise measurement of • the darkness of a mark, and the sophisticated mark • discrimination algorithm for determining whether a mark • is an erasure of a mark.

14. OCR(Optical Character Recognition) • It is the mechanical or electronic translation of • images of handwritten, typewritten or printed • text (usually captured by a scanner) into • machine-editable text. • OCR is less accurate than OMR but more • accurate than ICR. OCR can provide a good • alternative to pre slugged OMR grid such as • student ID number, thereby leaving free space • on the form for other design elements. • OCR technology gives scanning and imaging • systems the ability to turn images of machine • printed characters into machine readable • characters. Images of machine printed • characters are extracted from a bitmap • of a scanned image.

15. MICR(Magnetic Ink Character Recognition) • It is a character recognition technology • adopted mainly by the banking industry • to facilitate the processing of checks. • MICR characters at the bottom of the • paper in the E-13B font. • MICR characters are printed with a magnetic • ink or toner, usually containing iron oxide. • The error rate for the magnetic scanning of • the numbers at the bottom of a typical check • is smaller than with optical character • recognition systems.

16. Uses of OMR, OCR and ICR Products Include:

17. Modem (from modulator-demodulator) • It is a device that modulates an analog carrier • signal to encode digital information, and also • demodulates such a carrier signal to decode the • transmitted information. • The goal is to produce a signal that can be transmitted easily • and decoded to reproducethe original digital data. • Modems can be used over any • means of transmitting analog • signals, from driven diodesto • radio. • We connect external modems • to computers through the port • called RS-232.