GNDU B.Com (Bachelor of Commerce)

Chapter 2: Input/Output Devices and Computer Memory

Summary

Input devices are used to feed data and instructions into a computer, while output devices present the processed results to the user. Common input devices include the keyboard for typing, the mouse and joystick for pointing and control, and the light pen for drawing or selecting on screen. Several specialised input devices read marked or printed data automatically: the scanner converts documents and pictures into digital form, OMR (Optical Mark Recognition) reads marks such as those on answer sheets, OCR (Optical Character Recognition) reads printed characters, and MICR (Magnetic Ink Character Recognition) reads the magnetic-ink characters on bank cheques. The modem is a device that modulates and demodulates signals to connect a computer to communication lines. Common output devices include the printer, which produces a hard copy on paper, and the plotter, which draws high-quality graphics and engineering diagrams. Computer memory stores data and instructions and is of two main kinds. Primary memory is the main, fast, internal memory directly accessible to the processor; it includes RAM (random-access memory, which is volatile and lost when power is off) and ROM (read-only memory, which is permanent). Secondary memory is external, non-volatile storage of large capacity used to keep data permanently; secondary storage devices use magnetic media such as hard disks and optical media such as CDs and DVDs. Together, input, output and memory devices enable the computer to receive, store and deliver information.

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