Topics: Computer, Personal computer, Hard disk drive Pages: 45 (12612 words) Published: March 6, 2013
Information Technology
What is a computer?

CXC notes


It is an electronic device operating under the control of instructions stored in its own memory that can accept data, manipulate the data according to specified rules and produce results and store result for future use. Four fundamental functions are: 1. 2. 3. 4. Input Processing Output Storage

The computer comprises of a variety of hardware components. These include input device, output device, a system unit, storage device and a communication device. Input Device An input device is any hardware component that allows a user to enter data and instructions into computer. Input devices fall into four categories these are: Keyboard devices Point and draw devices Multimedia devices Automated input devices Keyboard devices Keyboard Point and draw devices Mouse Trackball Light pen Pointing stick Touch screen Touch pad Joystick Multimedia devices Pc camera Digital camera Microphone Web cam Automated input devices (devices that capture data directly from source) Optical Mark Reader Magnetic ink Character Reader Bar Code Reader Scanner STUDY HARD AND MAKE YOURSELF PROUD


Information Technology

CXC notes Optical Character Reader RFID (radio frequency identification) Magnetic Stripe Card Reader Keyboard devices


Keyboard-: This is an input device that is used to enter data, characters and commands into a computer. It is presently the main interfacing device of a command driven interface Point and draw devices Mouse-: This is a hand held point and draw device that contains at least one button. It is used to click on user interface items such as menus, buttons and icons. Trackball-: This is a ball used in a small external box or adjacent to or in the same unit as the keyboard; the trackball is rolled with the finger to move the cursor. Trackballs are mostly configured with portable computers. Light Pen-: This is a light sensitive input device which when it touches the screen detects the presence or absence of light. It is used to select an entry or indicate a position. Uses of a Light Pen-: i. ii. To choose from a list of options on a screen by pointing at the options required. To produce drawings on a screen by using a special function pad and a key board to indicate what the computer should draw and the pen to point where it should be drawn.

Joy Stick-: This is also a point and draw device that can move objects in any direction on the screen. It is mainly used for playing games. Automated input devices (Source Data automation) This is where special equipment is used to collect data at the source and send it directly to the computer. This process eliminates human error in data entry. Source Data Entry Includes: 1. Optical Mark Reader/Recognition 2. Magnetic Ink Character Reader/Recognition 3. Optical Character Reader 4. Bar code 5. Scanner 6. Sensor Optical Reader An optical reader is a device that uses a light source to read characters, marks and codes convert them into digital data that a computer can process. Two types of technologies used by optical readers are: Optical mark reader (OMR) and optical character reader (OCR). Optical Mark Reader (OMR) STUDY HARD AND MAKE YOURSELF PROUD


Information Technology CXC notes TUTOR: MR. G JAMES This is a technology that reads hand drawn marks such as small circles or rectangles. Marks are place on forms such as test, survey or questionnaire. Advantages of optical mark reader i. data is quickly and usually accurately captured ii. no machine is needed to complete the source document iii. the data preparation stage is largely eliminated Disadvantages of optical mark reader i. ii. iii. iv. The mark/no mark system can only be used if there are a limited number of alternatives for each response The marks must be accurate and clear or they will be misread. The source documents must be handled with care. Some data preparation staff will still be needed to correct and...
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