Enforcement Officer / Accounts Officer (EO/AO) 2017 recruitment test. Transcribed from the Commission's own booklet (series A, GRS-A-TNS); answer as per the official UPSC final answer key. This question is in Part B. Answer last reviewed 24 August 2026.

Which one among the following is not a basic function of a computer?

(a)Accept and process data
(b)Store data
(c)Scan text
(d)Accept input

Answer

Why

Correct — C, (c) Scan text. The ask is a negative one and the booklet prints the word not in bold italic, so the emphasis is part of what the question means: three of these are basic functions and the answer is the one that is not. The basic functions of a computer are conventionally given as four — accepting input, processing that input, storing data and instructions, and producing output — often remembered as the input, process, output and storage cycle. Some textbooks add control as a fifth, because the control unit directs the other four, but no standard list contains scanning.

Scanning text is not a function of a computer; it is a task performed by a particular piece of equipment attached to one. A flatbed or sheet-fed scanner illuminates a page, measures the reflected light and hands the machine an image, and turning that image into characters takes a further step, optical character recognition, done by software. A computer with no scanner attached cannot scan anything and is in no way less a computer for it, whereas a machine that could not accept input, could not process it, could not hold it or could not give anything back would not be a computer at all. That is the test the question is applying: a basic function is one without which the definition fails, and scanning is an optional capability supplied by an accessory.

It is worth noticing that the option set is not four separate functions. Option (a) contains two of them and option (d) repeats one of those two. That overlap is not an error and does not make either of them the answer — on a negative ask only one option has to be excluded, and the overlap is a sign that the examiner has listed the standard functions loosely while keeping the odd one out perfectly distinct.

Why the others are wrong

(a)Accept and process data — This option packs two of the four basic functions into one line. Accepting data is the input function, and processing it — performing the arithmetic and the comparisons, following the instructions one after another — is what the central processing unit exists to do and what gives the machine its name. Between them these two account for the greater part of any definition of a computer: a device that takes in data and transforms it into information according to stored instructions. Rejecting this option would mean rejecting the definition itself. A candidate who chooses it has almost certainly read the stem positively, as though it asked which option is a basic function, which is precisely the failure the printed emphasis on not is there to prevent.
(b)Store data — Storage is the third of the basic functions and, on the stored-program design that every ordinary computer follows, it is the one that makes the others useful. The machine holds not only the data being worked on but the instructions themselves, which is why a computer can be given a new task without being rebuilt. Storage happens at two levels: main memory, which the processor addresses directly and which loses its contents when the power goes, and secondary storage such as a disc, which keeps them. Both are the same function performed at different speeds and costs. A device that could accept and process data but could retain nothing would be a calculator at best, so this cannot be the option the question is asking for.
(d)Accept input — Accepting input is the first of the four basic functions and is the one every other function depends on: a machine that cannot be given data or instructions has nothing to process, nothing to hold and nothing to report. Input arrives through whatever device is attached — a keyboard, a mouse, a touchscreen, a microphone, a sensor, a network interface — but the function is the same whatever the device. This option restates part of what option (a) already contains, and a candidate who notices the repetition may be tempted to treat one of the two as the odd one out. The repetition is a feature of the drafting, not a signal: both statements are true of every computer, and only one option in the set describes something a computer does not do unless a particular accessory is bolted on to it.

Concept

A computer is defined by what it does rather than by what it is made of, and the standard definition lists four operations. It accepts input: data and instructions are brought in from a keyboard, a pointing device, a sensor, a network or a file. It processes: the central processing unit performs arithmetic and logical operations on that data under the direction of the instructions, its control unit fetching and decoding them one after another and its arithmetic and logic unit doing the work. It stores: data and instructions are held in main memory while in use and on secondary storage when not, which on the stored-program design is what allows the same machine to be turned to a new task simply by loading different instructions. And it outputs: results are presented on a screen, printed, played, transmitted or written back to storage. Some presentations add a fifth, control, to name the coordination of the other four. Everything else a computer appears to do — scanning a document, recognising a face, playing a film — is one of these four operations performed by a particular combination of an attached device and a program, and depends on that combination being present.

Negative asks are common in this paper and this is one of fourteen. The Commission emphasises the word not in bold italic, and it does so because the commonest way to lose an item of this kind is to read the stem as though it were positive, find the first option that is obviously true and choose it. Three of the four options here are obviously true, which means a candidate reading positively will pick one within seconds and never notice. The discipline that prevents it costs almost nothing: read the ask, say to yourself what you are looking for — here, the one that is not a basic function — and only then look at the options. The underlying point being tested is also worth having, because it separates the machine from its peripherals. An officer who understands that scanning belongs to a scanner and recognition to software will read a procurement note or an office circular more accurately than one who treats the whole assembly on the desk as a single undivided thing.

Key facts

The basic functions of a computer are conventionally four: accepting input, processing data, storing data and instructions, and producing output.
The cycle is often remembered by its initials as input, process, output and storage; some textbooks add control as a fifth function.
Processing is done by the central processing unit, whose arithmetic and logic unit does the work and whose control unit directs it.
On the stored-program design, the instructions are held in memory along with the data, which is what lets one machine perform any task.
Scanning is not a function of a computer but of an attached scanner, which converts a page into an image.
Turning a scanned image into editable characters requires optical character recognition software, a further step beyond the scan itself.
A computer without a scanner is in no way incomplete, whereas a device that could not accept input or produce output would not be a computer.
This paper prints the word not in bold italic on its negative asks, so the emphasis is part of the printed question.

A basic function is one without which the definition fails

(c) Scan text — not a function of a computer→It is a task performed by a particular piece of equipment attached to one. A flatbed or sheet-fed scanner illuminates a page, measures the reflected light and hands the machine an image; turning that image into characters takes a further step, optical character recognition, done by software.

The test the question applies→A computer with no scanner attached cannot scan anything and is in no way less a computer for it, whereas a machine that could not accept input, could not process it, could not hold it or could not give anything back would not be a computer at all.

The four basic functions→Accepting input; processing that input; storing data and instructions; producing output — the input, process, output and storage cycle. Some textbooks add control as a fifth, because the control unit directs the other four. No standard list contains scanning.

(a) Accept and process data→Two of the four packed into one line. Accepting data is the input function, and processing it — performing the arithmetic and the comparisons, following the instructions one after another — is what the central processing unit exists to do and what gives the machine its name. Rejecting this would mean rejecting the definition itself.

(b) Store data→The third function, and on the stored-program design the one that makes the others useful: the machine holds not only the data being worked on but the instructions themselves, which is why it can be given a new task without being rebuilt. A device that could accept and process but retain nothing would be a calculator at best.

(d) Accept input — and the overlap→The first function, on which every other depends. It restates part of what option (a) already contains, and a candidate who notices the repetition may treat one of the two as the odd one out. The repetition is drafting rather than a signal: on a negative ask only one option has to be excluded, and only one here describes something a computer does not do unless an accessory is bolted on.

Study next

The input, process, output and storage cycle, with an example of each stage from an ordinary office taskThe parts of the central processing unit — the arithmetic and logic unit, the control unit and the registersInput and output devices classified, and the peripherals that are both at once, such as a touchscreen or a network cardDevice drivers and how the operating system mediates between a program and an attached peripheralThe stored-program concept and why holding instructions in memory made the general-purpose computer possible

Common traps

Reading a negative ask positively and choosing the first true statement; on this item three of the four options are true.
Treating a peripheral's capability as the computer's own function, which would make printing, scanning and photographing all basic functions.
Being unsettled by the overlap between options (a) and (d); both are true, and on a negative ask only one option must be excluded.
Forgetting that scanning produces an image, and that recognising the text in that image is a separate software step.
Missing the bold italic emphasis on not, which the paper prints precisely because the ask is easy to invert.

EPFO computer blocks test the definition of the machine at least as often as they test any particular technology, and the negative form is the examiner's favourite because it punishes a candidate who reads quickly rather than one who knows little. The 2020 paper asks the same question from the other side, listing four basic operations for converting raw input data into useful information and asking which one is not performed by all computers. Between them the two items make the point that a function is basic when the definition of a computer fails without it, and that anything supplied by an attachment is not. The preparation is short: hold the four functions in order, attach one everyday example to each, and treat any option naming a specific device or a specific piece of software as a candidate for the odd one out.

Related PYQs

EPFO_EOAO_2020_Q27

Which one of the following basic operations for converting raw input data into useful information is not performed by all computers ?

(a) Inputting
(b) Storing
(c) Switching
(d) Outputting

Answer(c) Switching

The same idea asked from the other side three years later — which basic operation for turning raw input data into useful information is not performed by all computers.

EPFO_EOAO_2020_Q67

Which one of the following statements is correct ? A device driver of output devices

(a) interprets input provided by users into computer usable form.
(b) interprets computer output into user understandable form.
(c) translates user inputs into output device.
(d) facilitates user to communicate with output device.

Answer(b) interprets computer output into user understandable form.

The machinery that connects a peripheral such as a scanner or a printer to the computer: what a device driver for an output device actually does.

Practice

practice — not a real PYQ
Which one of the following sequences correctly represents the basic operating cycle of a computer?
- (a)Storage, input, output, processing
- (b)Input, processing, output, storage
- (c)Processing, storage, input, output
- (d)Output, processing, input, storage
Answer(b) Input, processing, output, storage
practice — not a real PYQ
Converting a scanned page into text that can be edited in a word processor requires
- (a)a higher scanning resolution alone
- (b)optical character recognition software
- (c)a colour rather than a monochrome scanner
- (d)additional main memory in the computer
Answer(b) optical character recognition software

Why