Source Data-Entry Devices: these devices are used for direct data entry to the computer systems. Few of them are as under:
Mark – and character-recognition device
- MICR (Magnetic-Ink Character Recognition)
- OMR (Optical Mark-Recognition)
- OCR (Optical Character-Recognition)
- Magnetic-Stripe Cards
- Smart Cards
- Audio-input device
- Video-input device
- Digital camera
Note : scanners use laser beams and reflected light to translate images of text, drawings, photos, and the like into digital form.
Bar-Code Reader: bar codes are the vertical zebra-stripped marks we find on most of the manufactured products in the market. This bar-code system is also called the “Universal Product Code”. These are read by bar-code readers, photoelectric scanners that translate the bar-code symbols into digital code, which is then fed to the computers for further processing.
MICR: it is a method of machine-reading characters made of magnetized particles. MICR equipment, producing a digitized signal, which goes to the computer as data for further processing.
OMR: optical recognition systems use a light beam to scan input data to convert in into electrical/digital signals, which are then sent to the computer for processing. The most well known example is the OMR technology used to read the SAT and GRE test marks.
OCR: it uses a device that reads preprinted characters in a particular font and convert them to digital code the common examples are some utility bills, and price tags in the department stores.
Magnetic-strip cards: a magnetic-strip card has a strip of magnetically encoded data on its back. They are used for personal identification during driving. In the stores, at public places etc.
Smart cards: it looks like a credit card but a microprocessor and memory chip have been added additionally. When inserted into a reader, it exchanges data with the corresponding information on a central computer. It can store some basic information also. A mobile-SIM card and an ATM card are good examples of this type.
Fax Machine: the fax or facsimile transmission machine scans an image and sends it as electrical signals over telephone lines to a receiving fax machine, which re-creates the image on paper, we have two types of fax machines i.e. dedicated fax machines and fax modems. Dedicated fax machines are the normal fax machines whereas, the fax modem is a circuit board inside the system unit. It has a capability to send signals directly to someone else’s fax machine or computer fax modem, from computer to computer.
Imaging System: image scanner (graphic scanner converts text, drawings, and photographs into digital form and stores it to the computer system for further processing. The system scans each image (color or black and white) with light and breaks the image into light and dark dots or color dots, which are then converted to digital form. This is also called raster graphics, which refers to the technique of representing a graphic image as a matrix of dots.
Audio video input devices
Audio-input device: an audio-input device records analog sound and translate it for digital storage and processing. The principal use of audio-input for multimedia computers. Which incorporate text. graphics, sound, video and animation is a single digital presentation. Sound (analog form) goes through a special circuit board called an audio board, which converts analog sound to digital form and stores it for further processing and/or plays it back. Microphone is mostly used as an audio-input device.
Video-input device: films and video images from VCR or camcorder are converted to digital form with the help of a special digitizing card (called video-capture card). It has two types:
Frame-grabber video card: it can capture and digitize only a single frame at a time.
Frame-grabber video card: also known as adapters, can convert analog to digital signals at the rate of up to 30 frames per second, giving the effect of a continuously flowing motion picture.
Digital camera: A digital camera uses a light-sensitive processor chip to capture photographic images in digital form on a small diskette inserted in the camera or on flash-memory chips. The digital form is then uploaded to the computer for manipulation and printing out.