Which of the following is not an output device ?
2015
Which of the following is not an output device ?
Answer: D. Keyboard — Concept — Every peripheral is classified by the direction in which data travels between the user and the processor. An input device carries data from the…
- A.
Printer
- B.
Speaker
- C.
Monitor
- D.
Keyboard
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Correct answer: D
Concept — Every peripheral is classified by the direction in which data travels between the user and the processor. An input device carries data from the outside world into the machine so it can be processed. An output device carries already-processed data out of the machine and converts it into a form a person can perceive: print, an image, or sound. A peripheral that only feeds data inward therefore cannot be an output device.
Application — Apply that direction test to each listed peripheral:
Peripheral | Direction of data | Class |
|---|---|---|
Printer | Processed data leaves the computer and is reproduced on paper | Output |
Speaker | Processed audio leaves the computer and becomes sound waves | Output |
Monitor | Processed video leaves the computer and becomes an on-screen image | Output |
Keyboard | Keystrokes enter the computer as character codes to be processed | Input |
Cross-check — Three of the four peripherals end the data path at the user, so each of them is an output device and none of them answers a question that asks which peripheral is not one. The keyboard sits at the opposite end of the same path: it starts the data path, supplying the machine with something to process rather than delivering a processed result. Note that some peripherals are bidirectional — a touchscreen both displays and accepts touch, a modem both sends and receives, and a multifunction printer also scans — so the direction test must be applied to the device as it is used, not to its name.
Result — The keyboard is the peripheral that is not an output device; it is an input device.