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

Correct — C, (c) Switching. Read the ask carefully first: the booklet prints 'not' in bold italic, and the question wants the item that is NOT one of the basic operations every computer performs. The standard description of what a computer does — the information processing cycle — has four operations: it takes in raw data (input), works on that data according to instructions (processing), holds data and instructions for later use (storage), and presents the results in usable form (output). Inputting, storing and outputting are three of those four, and the fourth, processing, is the step that actually turns raw data into information. Switching is not on the list. It belongs to data communication and networking, where a switch or a router directs traffic along a path — circuit switching and packet switching are the classic techniques — and a computer that is not connected to a network performs no switching at all while still doing everything a computer is supposed to do. That is exactly the sense in which it is 'not performed by all computers'.

Why the others are wrong

• (a)Inputting — Inputting is the first operation of the cycle and is universal: raw data has to enter the machine before anything can be done with it, whether through a keyboard, a mouse, a scanner, a touchscreen, a microphone, a sensor or a file read from a disk. A machine with no way of receiving data would have nothing to process. Because the question asks which operation is NOT performed, a genuine member of the cycle cannot be the answer.
• (b)Storing — Storing is the operation that holds data and the instructions acting on it, both in the short term while work is in progress and in the longer term for retrieval later. It is what separates a computer from a calculator that forgets everything between sums: the stored-program idea, that instructions live in memory alongside the data they operate on, is the foundation of the modern computer. So storage is performed by every computer, and this option is a true description rather than the exception the stem is hunting.
• (d)Outputting — Outputting is the last operation of the cycle — presenting processed results in a form a person or another machine can use, through a display, a printer, a speaker or a file written back to storage. Results that are never delivered are of no use to anyone, so no working computer omits this step. Like inputting and storing, it is a correct entry on the list and therefore cannot answer a question that asks for the item off the list.

The information processing cycle is the standard four-step account of what any computer does, and the four steps are input, process, store and output. Raw data enters; the processor applies instructions to it and produces information — data given meaning, arranged so that a decision can be taken on it; memory and storage hold both the data and the instructions before, during and after the work; and output delivers the result. The distinction between data and information is what the stem's phrase 'converting raw input data into useful information' points at, and it is the processing step that performs that conversion. Mapped onto hardware, input is keyboards, scanners and sensors; processing is the CPU, whose arithmetic and logic unit does the calculation and whose control unit sequences the instructions; storage is main memory together with disks and solid-state drives; output is monitors, printers and speakers. Switching sits in a different subject entirely — the movement of data between machines. In a network, a switch forwards frames to the device they are addressed to, and the two classical methods of moving traffic are circuit switching, which reserves a whole path for the duration of a call, and packet switching, which chops a message into packets that find their own way. Networking is something computers may do, not something every computer must do.

Key facts

• The information processing cycle: input, processing, storage, output.
• Processing is the step that converts raw data into information; the stem's wording points at it, and it is the one member of the four not offered as an option.
• Data is raw and unorganised; information is data that has been processed into a form with meaning for a decision.
• Inside the CPU, the arithmetic and logic unit performs calculations and comparisons while the control unit fetches, decodes and sequences instructions.
• The stored-program principle keeps instructions in memory alongside data, which is why storage is a basic operation and not an optional extra.
• Switching is a data-communication function: circuit switching reserves a path for the whole session, packet switching splits a message into packets routed independently.
• A network switch forwards data only to the port of the addressed device, unlike a hub, which repeats it to every port.

Common traps

• Missing the bold-italic 'not' and picking the option that is most obviously a computer operation.
• Treating 'processing' and 'storing' as one step, which leaves you looking for a fourth operation among the options and makes switching look plausible.
• Assuming that because most computers today are networked, switching must be a basic computer operation. The ask is about what ALL computers do.
• Confusing a network switch with an electrical on/off switch, which is a different sense of the word altogether.
• Reading each option for truth instead of against the ask. Three of the four are true statements about computers; only one answers the question.

• practice — not a real PYQ

  In the information processing cycle, which one of the following operations converts raw data into information ?

  • (a)Inputting
  • (b)Processing
  • (c)Storing
  • (d)Outputting

  Answer(b) Processing

• practice — not a real PYQ

  Packet switching is a technique associated with which one of the following ?

  • (a)The arithmetic and logic unit of a CPU
  • (b)Data communication over networks
  • (c)Secondary storage devices
  • (d)Output devices

  Answer(b) Data communication over networks