Input and output device questions look like simple recall, but their options deliberately mix four different ideas: the direction of data flow, the physical mechanism of a device, the unit used to compare devices, and whether a part belongs to the processing core or hangs off it. The twelve previous-year questions below are drawn from UP Police, BPSC, RSSB, KVS, NVS and EMRS papers. Attempt an item before reading its explanation, then note which of the four ideas tripped you. If you are revising the wider Computer Architecture syllabus, the GATE CS Exam Preparation Courses and Test Series page places this practice in a broader sequence.
Input and output device roles: trace the direction of data
Input moves data towards the computer, processing transforms it, and output presents the processed information. That single ordering settles all three questions here.
Question 1: Output unit
Output unit is responsible for _________.
(A) display output
(B) taking input
(C) processing input
(D) None of these
Answer: (A) display output. Follow the sequence: input unit, CPU processing, then output unit. A monitor, printer, or speaker presents the result; it does not capture or process the original input.
Solved question, UP Police 2017.
Question 2: Machine-readable input
Identify the unit that converts user data into machine readable form.
(A) Control unit
(B) ALU unit
(C) Output unit
(D) Input unit
Answer: (D) Input unit. It accepts a human action or physical signal and encodes it for the system. The control unit coordinates, the ALU computes, and the output unit presents results.
Solved question, UP Police 2017.
Question 3: An input-only set
Which of the following set contains only input devices?
(A) Printer, Speaker, Monitor
(B) Keyboard, Mouse, Printer
(C) Keyboard, Mouse, Scanner
(D) Printer, Scanner, Speaker
Answer: (C) Keyboard, Mouse, Scanner. Classify every item, not just the first. These three send data in, while every other set includes a printer, speaker, or monitor that sends information out.
Solved question, Eklavya Model Residential Schools 2023.
Mixed and specialised input devices: function beats appearance
Classify a device by function, not its most visible part. A touch screen sends display information out and touch coordinates in; specialised input devices are classified by the signals they capture.
Question 4: Touch screen classification
Touch screen is a/an _________.
(A) Input device
(B) Output device
(C) combination of both input and output device
(D) None of these
Answer: (C) combination of both input and output device. Pixels display the interface, while the touch sensor reports the user's contact coordinates. Both directions occur in one assembly, so neither input-only nor output-only is complete.
Solved question, UP Police 2017.
Question 5: Cheque processing
Which data input method do banks mainly use for processing bank cheques?
(A) OMR
(B) Bar Code Reader
(C) MICR
(D) Light Pen
Answer: (C) MICR. Magnetic Ink Character Recognition reads machine-readable characters printed on cheques. OMR detects marked bubbles, a bar code reader scans coded bars, and a light pen points at a screen.
Solved question, Navodaya Vidyalaya Samiti 2014.
Question 6: Trackball mechanism
An input device which comprises of an exposed protruding ball held by a socket having sensors for detecting ball's rotation for capturing input is:
(A) Touchpad
(B) Track ball
(C) Pointer
(D) Sensor ball
Answer: (B) Track ball. A trackball stays fixed while socket sensors translate ball rotation into pointer movement. A touchpad is flat, while pointer and sensor ball are not the standard hardware name described.
Solved question, Kendriya Vidyalaya Sangathan 2023.
Impact printers and print quality: mechanism and measurement
Impact printers use physical contact through a print head and ribbon. Character, line, and page printers form a character, line, or page respectively. Resolution is expressed as dots per inch, or DPI.
Question 7: Impact printing
An impact printer prints characters using:
(A) ink pen
(B) laser beam
(C) inked ribbon and print head
(D) electrically charged ink
Answer: (C) inked ribbon and print head. The print head physically strikes an inked ribbon against paper, which defines the impact mechanism. Laser and electrically controlled ink processes do not use that mechanical strike.
Solved question, UP Police 2016.
Question 8: Printer quality
The quality of a printer is determined as
(A) words per inch
(B) strike per inch
(C) dots per inch
(D) More than one of the above
(E) None of the above
Answer: (C) dots per inch. DPI measures how densely individual printable dots can be placed along one inch, so it describes resolution. Words per inch and strike per inch are not the standard resolution unit in this option set.
Question 9: Line printer and page printer
Which of the following are line printer and page printer respectively?
(A) Laser Printer, Dot Matrix Printer
(B) Drum Printer, Band Printer
(C) Drum Printer, Laser Printer
(D) Laser Printer, Chain Printer
Answer: (C) Drum Printer, Laser Printer. A drum printer is a line printer because it prints an entire line during a cycle, while a laser printer images and transfers a page. The word respectively fixes the order, so the line printer must appear first and the page printer second.
Output-device operating constraints: power is part of the mechanism
Power draw follows from mechanism. A laser printer fixes toner with a heated fuser, and that heater is what makes the machine awkward on a small UPS.
Question 10: A laser printer and a UPS
Which device is usually not connected to the UPS directly because of high power consumption?
(A) KVM switch
(B) External Mouse
(C) USB video camera
(D) Laser printer
Answer: (D) Laser printer. Its fuser heater draws a large current for a short period, which can overload a typical desktop UPS. The KVM switch, external mouse, and USB video camera are low-power peripherals by comparison.
Solved question, UP Police 2018.
Peripherals and external storage: classify, then normalise units
A peripheral is auxiliary hardware outside the CPU and main-memory core. For capacity comparisons, convert every option to one unit before ranking.
Question 11: Peripheral devices
Which is NOT a peripheral device?
(A) Visual display unit
(B) Main Memory chip
(C) Modem
(D) Pen Drive
Answer: (B) Main Memory chip. Main memory belongs to the computer's processing core and is used directly by the CPU. The display, modem, and pen drive are auxiliary output, communication, and storage peripherals.
Solved question, UP Police 2013.
Question 12: Highest storage capacity
Which of the following external storage devices provides the highest storage capacity among the given options?
(A) 16 GB Pen Drive
(B) 1024 KB Pen Drive
(C) 1 TB External Hard Disk
(D) 512 MB External Hard Disk
Answer: (C) 1 TB External Hard Disk. Under the binary unit convention used by this item, first convert every capacity to GB:
16 GB = 16 GB
1024 KB = 1 MB = 1/1024 GB = 0.0009765625 GB
1 TB = 1024 GB
512 MB = 512/1024 GB = 0.5 GB
Therefore, 1024 GB is larger than 16 GB, 0.5 GB, and 0.0009765625 GB. Normalising the units prevents the printed numerals 16, 1024, 1, and 512 from misleading you.
Solved question, Eklavya Model Residential Schools 2026.
Input Output Devices MCQ traps: four checks to reuse
Four checks catch nearly every trap this topic sets:
Check | Question to ask | Example from this set |
|---|---|---|
Direction of data flow | Does information move towards or away from the computer? | Question 3, where keyboard, mouse, and scanner all send data in |
Physical mechanism | What does the device physically sense, strike, heat, or transfer? | Question 7, where the print head strikes an inked ribbon |
Standard measurement or unit | Which unit describes the property, and have all values been normalised? | Question 12, where every capacity is converted to GB |
Core component or peripheral | Is the hardware inside the CPU and main-memory core, or auxiliary to it? | Question 11, where main memory is not a peripheral |
These twelve come from state police, state commission and school-service recruitment papers, so the four checks transfer across very different syllabi. More than fifty solved questions sit in the same Input Output Devices module when you want a longer run.
For the wider storage hierarchy, Memory Hierarchy and Virtual Memory: Paging and TLB shows where external storage sits. Cache Memory Mapping and Hit Ratio: Solved Examples covers the faster levels closer to the CPU.
The short version and the next practice step
For any input or output device, ask what crosses the computer boundary, by what mechanism, and in which direction. Redo these 12 items without reading the explanations, then note whether each error came from classification, terminology, or unit conversion.
If you want the subject in order rather than isolated practice, GATE Guidance by Sanchit Sir walks Computer Architecture end to end. For the next concept after the device layer, Pipelining in Computer Architecture: Speedup and Hazards covers instruction overlap and the hazards it creates.
