The image generally does not appear on the tablet itself but is displayed on the computer monitor. It consists of a flat surface upon which the user may draw an image using an attached stylus, a pen-like drawing device. Graphics Tablet: A graphics tablet is a computer input device that allows us to hand draw image and graphics similar to the way we draw images with pencil and paper. If the pattern matches, the data is transmitted to the computer which displays the details of the item and in many cases also updates the inventory and sale record.Ĩ. They are then compared with the already fed patterns in the computer.
#Keyboard class 9 solutions code#
When the bar code is scanned, reflected light patterns are converted into electrical pulses. These bar codes are read by hand¬held optical readers or fixed bar code readers and contain the information about the item like the price, code, weight, manufacturer details etc. Bar Code Reader: You must have noticed a pattern of bars on the items you buy from the market, similar to the one shown in Fig. The light is absorbed by the characters and thus recognized by the OCR.ħ. The characters to be read by OCR are written in a specific font and the printed matter is scanned with a photoelectric device. Optical Character Reader (OCR): This technique allows direct reading of any printed character.
The sheet is then exposed to a beam of light and the answers on the sheet are sensedīy OMR.
The user is required to mark one option out of a given number of options on a specially designed response sheet. It is mostly used in the evaluation of multiple choice question papers. Optical Mark Reader (OMR): This input device also senses data directly from the document. Whenever any transaction is made through a credit card, the magnetic code and details of the transaction and card are captured by the card reader.ĥ. A similar type of magnetic code can be seen on credit cards also. MICR can process 40 documents per second. When these cheques have to be processed, they are put in a MICR, which reads the magnetic code written on the cheque. These numbers are written in a special font using a special magnetic ink. Magnetic Ink Character Reader (MICR): You must have seen cheques on which numbers are printed at the bottom. Electric pulses send data to the computer and it can detect which menu option has been selected.Ĥ. These photocells when activated generate electric pulses. When the pen is brought in contact with the screen, it detects the light emitted by the screen and this light activates the photocells. A special pen which has photo cells in its tube is attached to the monitor. Light Pen: It is a device for direct data entry. It uses the reflected light to sense the direction of movement.ģ. Nowadays optical mouse is very much in demand. When a user rolls the mouse on a flat surface, the cursor moves accordingly on the screen. It is about the size of a human palm and rolls on a small bearing and has one or more buttons on the top. Mouse: Another very popular input device is the mouse.
#Keyboard class 9 solutions manual#
The keyboard we normally use has 101 keys and is called QWERTY as it is similar to the manual typewriter which has Q, W, E, R, T, Y keys on its very first row of alphabets.Ģ. So, the input is converted into a computer understandable code by the keyboard itself. When a key is pressed, an electric signal exclusive for each key is generated which passes to the control unit. It has various keys like numeric keys (0 – 9), alphabetic keys (A – Z), function keys (FI – F12), some special purpose keys like Delete, PageUp etc., direction keys represented by arrow and symbol (*, |, 😉 keys. Keyboard: It is the most commonly used input device. There are many input devices like keyboard, mouse, joystick, light pen etc. The instructions and the data, on which a computer has to work, are fed to the computer by input unit/devices. CBSE Notes for Class 9 Foundation of Information Technology – Basic Components of a Computer SystemĪ computer system has three basic components:
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