Basic components of a computer system

The governing concept is that the monitor and system unit have different functions. The system unit contains the processor, memory, and other hardware that can continue executing instructions, while the monitor only presents visual output. Consequently, work may continue even though the user cannot see the screen. Turning off the monitor does not automatically erase data or permanently stop the processor, and it does not change a keyboard into an output device. Option C is correct.

The governing concept is hardware compatibility. An internal expansion card must have a physically matching connector and use a standard supported by the motherboard. If the connector cannot fit the available slot, the card cannot be installed normally, so it is incompatible with that motherboard or requires a different compatible interface. Storage capacity, monitor size, and memory volatility do not determine whether the card fits. Hence option D is the correct conclusion.

The governing concept is the memory hierarchy, which balances speed, size, and cost. Cache memory is generally smaller and faster than main memory, so it keeps frequently needed instructions and data close to the processor. Main memory, usually RAM, is larger but slower than cache and is not the same as a processor register. Therefore option C correctly compares the two; the other statements reverse or confuse their characteristics.

The governing concept is the distinction between volatile primary memory and non-volatile secondary storage. A solid-state drive, or SSD, stores data in flash memory and retains files even when electrical power is removed, so option D is correct. Registers, cache, and RAM are fast working memories used during processing; they are volatile or temporary rather than permanent secondary storage.

The governing concept is temporary power backup. An Uninterruptible Power Supply, or UPS, uses a battery and inverter to provide electricity for a short period when the main supply fails. This gives the user time to save work and shut the computer down safely, so option A is correct. A scanner, joystick, and webcam are input devices and cannot maintain computer power.

The governing concept is retention of firmware settings and the real-time clock. The CMOS battery supplies a small amount of power that helps preserve the computer’s date, time, and certain setup settings when it is switched off. If the battery weakens, these values may reset repeatedly, making option B correct. It cannot enlarge a monitor, double mouse speed, or increase storage capacity.

The governing concept is thermal management of the processor. A heat sink conducts and spreads heat away from the processor, increasing the surface area for cooling, while a cooling fan moves air across the heat sink and carries heat away. Therefore option C is correct. Printers, scanners, input devices, monitors, and projectors do not form the processor’s cooling system.

The governing troubleshooting principle is to check the simplest external connections before replacing working internal hardware. A monitor needs electrical power and a correctly connected display cable to receive and show the graphics signal. Therefore, option A is the sensible first check. Printer supplies, audio devices, scanners, and webcams do not normally control the monitor’s visual output, so options B, C, and D are unrelated.

The governing concept is the division of CPU functions into specialized subunits. The Arithmetic and Logic Unit, or ALU, performs addition, subtraction, comparisons, and other logical or arithmetic operations. If instructions are being read but the numerical results are wrong, the ALU is the most likely subunit involved. The control unit directs operations, while the power supply and network card do not calculate values.

The governing concept is the control unit’s role in directing and coordinating computer operations. It interprets instructions and sends control signals so that the processor, memory, input, and output units work in the proper order. If it malfunctions, coordination among these units can break down. A screen colour, disk capacity, or speaker volume does not automatically change because of such a fault, so A, C, and D are incorrect.

The governing concept is volatility. RAM is volatile working memory: it temporarily holds active programs and data, and its contents normally disappear when power is removed. ROM is non-volatile and commonly stores firmware or startup instructions that remain available during booting. Option A wrongly calls both external devices, C makes an unsupported claim about capacity, and D reverses RAM’s volatile behavior. Therefore B is the accurate distinction.

The governing concept is the role of non-volatile firmware memory in the boot process. Startup instructions are commonly stored in ROM or firmware storage so that they remain available even when the computer has been switched off. If those instructions cannot be found or read at every startup, ROM is the best answer among the choices. RAM is temporary, cache accelerates access, and a pen drive is removable storage rather than the normal source of firmware.

The governing concept is the difference between electronic flash storage and mechanical magnetic storage. An SSD stores data in flash memory and has no spinning platters or moving read/write heads. This removes mechanical seek and rotation delays, so access and many file operations are generally faster than on an HDD. An SSD is not faster because of a screen, temporary-only storage, or direct networking; therefore D is correct.

The motherboard is the main circuit board and provides electrical connections and communication pathways for the CPU, RAM, storage devices and expansion cards. Therefore, option A is correct: it links these major components so they can exchange data and work as one system. The other options describe a sound device, printer or networking device, not the motherboard’s central connecting function.

RAM must match the motherboard’s supported generation, form factor and electrical requirements. If the module is incompatible, it may not fit, may not be detected, or may prevent the computer from completing startup. Thus option B is correct. Screen size, printer speed and speaker tone are unrelated to RAM compatibility and would not normally result from installing the wrong memory type.

An expansion slot is a connector on the motherboard designed for an add-on card, such as a graphics, sound or network card. Installing an additional graphics card therefore requires a suitable expansion slot, making option C correct. Cleaning a monitor and renaming a file require no internal slot, while scanning paper uses a scanner connected through an external interface.

A motherboard bus carries data and control signals between important components such as the processor, memory and expansion devices. A lower bus speed can reduce the rate at which these components communicate and may limit overall system performance. Option D is correct. Printer ink, monitor brightness and mouse size are not direct functions of the internal bus-transfer rate.

The power supply unit must provide sufficient, stable electrical power to the processor, motherboard, drives and other components. If its capacity is too low, voltage may become unstable when the system is under load, causing crashes, unexpected shutdowns or failure to start. Option A is correct. File names, mouse direction and monitor dimensions are not normal effects of inadequate PSU capacity.

The CPU produces heat while processing instructions, and its cooling fan helps move that heat away from the heat sink and case. If the fan stops, temperature can rise rapidly, leading to thermal throttling, sudden shutdowns or possible hardware damage. Therefore, option B is correct. Printer ink, mouse signals and file extensions are not the primary risks of CPU cooling failure.

A heat sink has a large metal surface that absorbs heat from the CPU and spreads it over a wider area. The fan moves air across that surface, carrying heat away from the processor and reducing its temperature. Thus option C correctly describes their complementary cooling roles. They do not create backups, increase network speed or store electrical energy.

Dedicated graphics memory, often called video memory, stores textures, frames and other visual data close to the graphics processor. This reduces dependence on general system RAM and allows images, video and 3D scenes to be handled more efficiently. Option D is correct. The memory does not supply printer paper, power a keyboard or function only as a sound recorder.

Recording proves that the input path, such as a microphone and recording circuit, captured sound, but playback uses a separate output path. The sound card, playback settings, volume control, selected output device and speakers should therefore be checked. Option A is correct. A scanner, printer, mouse, keyboard, router or modem does not normally control audio playback.

The network interface card, or NIC, provides the computer’s wired Ethernet connection and communicates with the network through the cable. If the cable is connected but no network is detected, the NIC, its indicator lights, driver and port should be checked. Option B is correct. A graphics card handles images, a sound card handles audio, and cache memory supports fast processing rather than network access.

The governing concept is the role of networking devices. A switch forwards data between devices on the same local area network, using device or MAC addresses. A router connects separate networks and chooses a path for packets, such as traffic moving from a home network to the internet. Therefore, option C correctly distinguishes their functions. Option B reverses the roles, while A and D describe neither device.

A modem and a router have different governing functions even though many household units combine them. A modem converts signals between the internet service line and digital network data, while a router directs packets between the local network and other networks. Thus option D is correct. The other choices wrongly describe both devices as internal, printing, or storage equipment and ignore their communication roles.