Basic components of a computer system

The governing concept is the role of the arithmetic logic unit, or ALU, inside the CPU. It performs arithmetic operations such as addition, subtraction, multiplication, and division, and carries out logical operations or comparisons such as greater than, less than, and equal to. Hence, option C is correct. File management is handled by the operating system and storage, power is managed by power hardware, and printing is performed by a printer.

The governing concept is the position and purpose of CPU registers. Registers are very small storage locations inside the central processing unit that hold an instruction, operand, address, or intermediate result currently needed by the CPU. Because data travels only a very short distance and registers are accessed directly during processing, they are faster than cache, RAM, and secondary storage. Thus, option D is correct; the other choices incorrectly place them in external or disk storage or limit their contents to images.

The governing concept is the cache hierarchy between the processor and main memory. Cache stores copies of instructions and data that the CPU is likely to use again, so the processor can retrieve them faster than it usually can from RAM. This reduces waiting time and may improve performance; it does not provide permanent backup. Therefore, option A is correct. Printing is an output function, and internet signalling belongs to communication hardware, not cache memory.

The governing concept is volatility and purpose. RAM is generally volatile working memory: it temporarily holds programs and data that the processor is actively using, and its contents disappear when power is removed. ROM is non-volatile and stores firmware or other instructions that must remain available after shutdown. Therefore, option B is correct. A is false because RAM is not permanent, C wrongly limits ROM to images, and D reverses RAM’s power-loss behavior.

The governing concept is the different role and access pattern of memory types. Primary memory, such as RAM and cache, provides the CPU with relatively fast access to instructions and data currently needed for processing. Secondary storage, such as an SSD, hard drive, or memory card, keeps files and programs for long-term use and normally retains them without power. Therefore, option D is correct; the other choices confuse storage with printing, networking, or computation.

The governing concept is magnetic storage. In a traditional hard disk drive, data is recorded as changing magnetic patterns on the surfaces of rapidly rotating platters. A read/write head detects these patterns and changes them when data is written. Therefore, option B is correct. Light signals describe optical media, wires merely carry signals, and paper cannot store digital data in a hard disk.

The governing concept is system interconnection. The motherboard is the main circuit board that provides physical connections and communication pathways for the processor, memory, storage devices, expansion cards and other hardware. It may also distribute power and coordinate data transfer through buses. Thus option C is correct. Sound production and printing are functions of specific peripherals, while deleting files is an operating-system action.

The governing concept is thermal management. A cooling fan moves air through the computer so that heat produced by the processor, power supply and other components is carried away. Keeping temperatures within a safe range helps prevent overheating, performance reduction and possible hardware damage. Therefore option C is correct. Fans do not add storage, record sound or enlarge images; those tasks belong to other components or software.

The governing concept is audio signal processing. A sound card, whether a separate expansion card or integrated circuitry, converts digital audio into signals that speakers or headphones can reproduce and converts microphone input into digital data for the computer. Thus option C is correct. Loading the operating system is mainly a storage and processor task, printing belongs to a printer, and cooling the hard disk is unrelated to audio hardware.

The governing concept is network connectivity. A network interface card, or NIC, provides the hardware interface that allows a computer to send and receive data over a wired or wireless network. It works with network protocols and the operating system to support communication with other devices. Therefore option D is correct. Calculations are mainly handled by the processor, image creation by graphics hardware or software, and power backup by a UPS.

The governing concept is peripheral connectivity. A USB port uses a standard interface to connect devices such as keyboards, mice, storage drives, cameras and printers, allowing data transfer between them and the computer. Many USB ports can also supply limited electrical power, although their capabilities depend on the version and design. Therefore option A is correct. USB is not limited to audio, is not the CPU itself, and does not merely switch power off.

The governing concept is the difference between image capture and text recognition. A scanner captures a paper document as a digital image. OCR then analyses the shapes of printed characters in that image and converts them into selectable or editable text. Therefore option B is correct. A scanner does not print, and neither scanner nor OCR is itself a storage device.

OMR and OCR are different optical input technologies. OMR detects selected or filled marks in fixed positions, such as bubbles on an examination answer sheet. OCR analyses the shapes of printed or handwritten characters and converts recognized text into digital form. Hence option C is correct; magnetic ink belongs to MICR, not OMR or OCR.

MICR is a banking input technology based on characters printed with magnetically readable ink or toner. A cheque reader senses those characters and helps financial systems process account and cheque information accurately, even when ordinary marks or stamps are present. Therefore option D is correct. MICR does not colour paper, measure thickness, or create signatures.

Refresh rate is the number of times a monitor redraws or updates its displayed image in one second, measured in hertz (Hz). For example, 60 Hz means up to 60 updates per second. A higher rate can make moving images appear smoother, provided the computer and display support it. Therefore option C is correct; storage, paper size, and mouse speed measure different properties.

A microphone is an audio input device. Its diaphragm responds to sound-pressure vibrations and the device converts those vibrations into an electrical signal; a computer’s audio circuitry can then sample it and represent it digitally. Hence option D is correct. A paper document, magnetic platter, and visual pixel are not the normal signal forms produced by a microphone, though audio may later be stored on a device.

A projector forms an image from a video signal supplied by a computer or another source. The source must provide a compatible signal and the selected resolution should suit the projector; focus, lens quality, and lighting also affect perceived clarity. Thus option C is the best answer. A sound card handles audio, a network card handles communication, and backup duration concerns power continuity rather than image sharpness.

A UPS contains a battery and provides temporary backup power when the mains supply fails, allowing continued operation or safe shutdown. A PSU is installed inside the computer and converts incoming AC into the regulated DC voltages required by the motherboard, drives, and other components. Therefore option D correctly distinguishes them. Neither device is primarily for data storage or central processing.

Hardware means the physical parts of a computer or device that can be handled, such as a circuit board, keyboard, or storage chip. Firmware is software consisting of persistent, low-level instructions stored in non-volatile memory within a device, helping its hardware start and perform basic functions. Therefore option B is correct. Firmware is not an external device, neither term is a user document, and hardware does not exist only online.

Static electricity can suddenly discharge through a circuit when a person touches an internal component. This brief high-voltage discharge may damage delicate chips, memory modules, or other electronic paths, even when no visible mark appears. Thus option A is correct. Static electricity does not increase storage, control printer speed, or clean a screen.

Air vents allow warm air to leave the cabinet and cooler air to circulate around internal components. When vents are blocked, heat accumulates, so the processor or other parts may slow down, become unstable, or shut down for protection. Therefore option B is correct; blocked vents cannot increase storage or change keyboard and monitor size.

Repeated shutdowns together with a very hot cabinet strongly suggest overheating. The initial troubleshooting step is to inspect whether the cooling fan works, dust is blocking it, and air can move through the vents. The computer may shut down automatically to prevent damage. Hence option A is correct; printer paper, file extensions, and mouse speed do not control internal temperature.

An expansion slot provides a physical and electrical connection for an add-on component such as a graphics, sound, or network card. If the slot is faulty, the card fitted in it may not receive power or communicate with the motherboard, so it may fail to operate. It does not normally delete documents, change RAM into permanent storage, or convert a monitor into a printer.

Data-bus width means the number of bits that can travel through the bus during one transfer cycle. For example, a 32-bit bus can carry twice as many bits per cycle as a 16-bit bus, under comparable conditions. Therefore, a wider bus can increase the amount of data transferred at one time, although total performance also depends on clock speed and other components.

The address bus carries the binary address of the memory location or input-output location that the processor wants to access. If it has n lines, it can represent up to 2^n distinct addresses. Adding more address lines therefore increases the number of addressable memory locations, rather than changing sound quality, monitor size, or printer speed.