Comp_Fundamentals_unit_2 by liuhongmei


									BCA103 - Computer Fundamentals

               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

                     •Familiar with the components of a computer system
                     •Helps to understand what an operating system is !
                      OS- which it facilitates the execution of programs

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BCA103 - Computer Fundamentals

               Central processing unit (CPU)

                    •Executes program, instruction

                    •It is single electronic component
                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

                    •Arithmetic-Logic unit (ALU): Perform operations
                    (arithmetic and logical)
                         •Mathematical: Sub, Div, Add, Multiply
                         •Logical: Comparisons of data

Department of BCA        Session: July 2008 – Nov 2008                    2/30
BCA103 - Computer Fundamentals

                Computer memory (data storage)
                •Computer data storage provides one
                 of the core functions that of information
               Types of memory:
               •Primary memory 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
               •Secondary storage today more commonly
               refers to mass storage - optical discs, forms
               of magnetic storage like hard disks

Department of BCA       Session: July 2008 – Nov 2008               3/30
BCA103 - Computer Fundamentals

               hard disk drive with               Hierarchy of storage
               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

Department of BCA       Session: July 2008 – Nov 2008                4/30
BCA103 - Computer Fundamentals

                                  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

Department of BCA       Session: July 2008 – Nov 2008                   5/30
BCA103 - Computer Fundamentals

              Input Device             Basic organization of a computer.

                O   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 motion typically translates into the motion
               of a pointer on a display, which allows for fine control of
               a Graphical User Interface.

Department of BCA       Session: July 2008 – Nov 2008                   6/30
BCA103 - Computer Fundamentals

               •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.

Department of BCA       Session: July 2008 – Nov 2008                  7/30
BCA103 - Computer Fundamentals


                    Joystick elements:
                    1. 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
              •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 clock movement is there

Department of BCA       Session: July 2008 – Nov 2008                  8/30
BCA103 - Computer Fundamentals

               •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         Image
               and other applications.

                Types of scanner
                 rotary scanner :used for high-speed
                 document scanning
                planetary scanner: used for takeing
                photographs of books and documents
                3D scanners, for producing three-dimensional models of

Department of BCA       Session: July 2008 – Nov 2008                9/30
BCA103 - Computer Fundamentals

               •Digitizing or digitization 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.

Department of BCA        Session: July 2008 – Nov 2008           10/30
BCA103 - Computer Fundamentals

                                 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

Department of BCA       Session: July 2008 – Nov 2008                 11/30
BCA103 - Computer Fundamentals

                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

Department of BCA       Session: July 2008 – Nov 2008             12/30
BCA103 - Computer Fundamentals

                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.

Department of BCA       Session: July 2008 – Nov 2008                    13/30
BCA103 - Computer Fundamentals

                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.

Department of BCA        Session: July 2008 – Nov 2008               14/30
BCA103 - Computer Fundamentals

               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.

Department of BCA       Session: July 2008 – Nov 2008          15/30
BCA103 - Computer Fundamentals

               Uses of OMR, OCR and ICR Products Include:

                                              •Quality Monitoring
                •Equality Monitoring
                •Medical OSCE's
                •Administration & Personnel
                                              •Performance Monitoring
                •Time Recording

Department of BCA        Session: July 2008 – Nov 2008                  16/30
BCA103 - Computer Fundamentals

                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 reproduce the original digital data.
               •Modems can be used over any
               means of transmitting analog
               signals, from driven diodes to
               •We connect external modems
               to computers through the port
               called RS-232.

Department of BCA       Session: July 2008 – Nov 2008                   17/30

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