1.1 Selection of Computer Hardware devices

The process of selecting computer hardware devices is a fundamental skill for ICT technicians in Kenya, requiring an understanding of device specifications, compatibility, and intended use. Whether configuring a computer lab at a university or setting up workstations in a retail business, technicians must assess the requirements carefully to optimise performance and cost-efficiency.

1.1.1 Introduction to computer devices

Computer devices consist of both hardware components and peripherals that work together to perform computing tasks. Understanding what these devices are, how to recognise them and how they are grouped is essential for ICT technicians tasked with assembling, repairing, or upgrading computers in environments such as hospitals or SACCO offices.

1.1.1.1 Meaning of computer hardware devices

Computer hardware refers to the physical parts of a computer system that can be seen and touched, including input, output, processing, and storage units. Hardware does nothing useful on its own: it needs software, which is the set of programs and instructions that tells the hardware what to do. Example: in a primary school computer room, the monitor, keyboard and system unit are hardware, while the operating system and the typing-tutor program running on them are software.

Hardware devices fall into two broad groups. Internal devices sit inside the system unit, for example the motherboard, processor, memory and storage drive. External devices (peripherals) connect from outside through ports or wireless links, for example the monitor, keyboard, mouse and printer.

The difference between hardware and software is summarised below.

1.1.1.2 Identification of computer components and port

Before selecting, assembling or repairing a computer, a technician must be able to recognise each component and port by its appearance and position. Correct identification prevents forcing a cable into the wrong socket and helps when ordering replacement parts. Example: at a courier company's front desk, a technician replacing a faulty computer must quickly tell the video port from the network port at the back of the system unit.

Main components to identify:

• System unit (case): The box that houses the motherboard, processor, memory, storage drives and power supply. It has a power button and usually front-panel ports.
• Monitor: The screen that displays output. It has a power cable and a video cable.
• Keyboard: A panel of keys arranged in the QWERTY layout, used to type text and commands.
• Mouse: A hand-held pointing device with buttons and a scroll wheel, used to move the pointer on screen.
• Motherboard: The large flat circuit board inside the case, with sockets, slots and connectors to which other parts attach.
• Processor (CPU): A small square chip seated in a socket on the motherboard, normally covered by a heat sink and fan.
• Memory modules (RAM): Narrow rectangular sticks that clip into long slots beside the processor.
• Storage drive: A hard disk drive is a metal box with a data cable and power cable attached; a solid-state drive is a thinner box or a small card that fits directly on the motherboard.
• Power supply unit: A metal box, usually at the top or bottom rear of the case, with a mains socket, a switch and a bundle of coloured cables.
• Expansion cards: Boards such as video or network cards that plug into slots on the motherboard, with their ports visible at the back of the case.

Common ports to identify:

• USB ports: Rectangular (Type-A) or small oval (Type-C) sockets used for keyboards, mice, flash disks, printers and many other devices. Type-A sockets often have a blue or black plastic tongue inside.
• HDMI port: A flat socket with slightly angled corners that carries digital video and sound to a monitor or projector.
• DisplayPort: Similar to HDMI but with one corner cut off, carrying digital video and audio to monitors.
• VGA port: A 15-pin, D-shaped socket, usually blue, carrying analogue video to older monitors and projectors.
• DVI port: A wide white or black socket with a grid of pins, used for video on some older graphics cards and monitors.
• Ethernet (RJ-45) port: A square socket slightly wider than a telephone socket, used for network cables. It often has small indicator lights.
• Audio jacks: Round 3.5 mm sockets for speakers, headphones and microphones. They are commonly colour-coded green for speakers or headphones, pink for a microphone and blue for line input.
• PS/2 ports: Small round six-pin sockets, found on older computers, usually purple for the keyboard and green for the mouse.
• Power inlet: A three-pin socket on the power supply unit where the mains cable plugs in.

1.1.2 Computer case, monitor, keyboard, and mouse

The external hardware components of a computer form the user interface and protect internal parts. Selecting these devices involves evaluating ergonomics, durability, and compatibility to suit professional environments like county offices or law firms.

Computer case types and features

Computer cases house and protect internal components from physical damage and dust. They come in various sizes, full tower, mid tower, mini tower, and small form factor, each suited to different space constraints and hardware configurations. For example, a mid tower is common in office setups due to its balance of expandability and size.

• Cooling and ventilation: Cases must provide adequate airflow to prevent overheating, especially in warm climates. Cases with multiple fan mounts and dust filters are preferred in places such as supermarket back offices.
• Build material: Steel cases offer durability but add weight, while plastic cases are lighter but less robust. Durability is crucial for mobile setups like those used by field technicians.
• Expansion slots and bays: Sufficient slots and bays allow for future upgrades such as additional drives or graphic cards, important for institutions like polytechnics anticipating growth.
• Cable management: Good cable routing options improve airflow and ease maintenance in busy ICT departments.
• Aesthetics and noise levels: Quiet cases with noise dampening features enhance working conditions in libraries.

Monitor selection criteria

Monitors display visual output and are critical for user interaction. Choosing the right monitor involves considering resolution, size, panel type, and connectivity. Example: a records clerk reading small figures on spreadsheets all day needs a sharper and larger screen than a receptionist who only checks appointment lists.

• Resolution: Higher resolution (e.g., Full HD 1920 × 1080 or 4K) provides clearer images and is essential for tasks requiring detail such as data analysis in banks.
• Size and viewing distance: Typical office monitors range from 21 to 27 inches, balancing screen real estate with desk space constraints.
• Panel technology: IPS panels offer better colour accuracy and viewing angles compared to TN panels, useful in the marketing offices of hotels.
• Refresh rate and response time: While crucial for gaming, standard office environments prioritise resolution and colour over refresh rates.
• Connectivity options: HDMI, DisplayPort, and VGA ports ensure compatibility with different computers in technical colleges.

Keyboard and mouse features

Keyboards and mice are primary input devices; their design impacts user comfort and efficiency. A device that suits the task reduces fatigue and errors. Example: a typist in a secretarial bureau who types for hours benefits from a comfortable keyboard with a firm, even key action.

• Keyboard types: Mechanical keyboards provide tactile feedback preferred by software companies for programming, while membrane keyboards are quieter and more affordable for general office use.
• Ergonomics: Split or curved keyboards reduce strain during prolonged typing sessions, beneficial in call centres.
• Mouse types: Optical and laser mice vary in sensitivity and surface compatibility. Wireless mice reduce clutter but require battery management.
• Additional features: Multimedia keys, programmable buttons, and adjustable DPI settings enhance productivity in graphic design or data entry roles at a printing press.
• Durability and cleaning: Devices used at busy public counters, such as a bus company booking office, must withstand frequent use and be easy to clean to maintain hygiene.

1.1.3 All the parts inside the computer case, such as the hard disk drive, motherboard and video cards

The internal components of a computer determine its core functionality and performance. ICT technicians must understand the specifications, roles, and compatibility of these parts to assemble, upgrade, or troubleshoot systems effectively in sectors like flour milling or manufacturing.

1.1.3.1 Classification of computer hardware devices

Hardware devices are classified by the function they perform in the processing cycle of input, processing, storage and output, with communication devices linking computers together. Knowing the class of a device tells a technician what role it plays and what to look for when selecting it. Example: a technician equipping a new office lists the input, output, storage and communication devices separately so that nothing is left off the order.

• Input devices: These enable users to enter data into the computer, such as keyboards, mice, and scanners. Input devices must be ergonomic and compatible with the system to ensure efficient data entry in fast-paced environments like insurance firms.
• Output devices: Devices such as monitors and printers display or produce results from processed data. Selecting high-resolution monitors is vital for graphic design tasks in advertising agencies.
• Processing devices: The central processing unit (CPU) interprets and executes instructions. Its speed and core count determine the system's ability to handle complex applications in places like engineering consultancies running design software.
• Storage devices: Hard drives and solid-state drives store data permanently. Choosing between HDDs and SSDs affects speed and data reliability, important for data-sensitive institutions like a tax records office.
• Communication devices: Network cards and modems facilitate data exchange between computers and networks. Reliable network adapters are crucial for connectivity in county government offices.

Hard disk drives and solid-state drives

Storage devices hold the operating system, applications, and data. HDDs use spinning disks and are cost-effective for large capacities, while SSDs use flash memory, offering faster data access and durability.

• Capacity and speed: SSDs improve boot and application load times, critical in a dental clinic where quick access to patient records is necessary.
• Form factor: Common sizes include 3.5-inch for desktop HDDs and 2.5-inch for SSDs or laptop drives. Some SSDs are small cards that fit directly on the motherboard.
• Interface types: SATA is used by both HDDs and SSDs, while NVMe drives use the faster PCIe interface.
• Reliability and lifespan: SSDs have no moving parts, reducing failure risk in mobile setups like the field offices of a survey firm.
• Cost considerations: Balancing budget and performance is essential in public service procurement, for example when a state corporation buys many workstations.

Motherboard functions and features

The motherboard is the main circuit board connecting all components and peripherals. It determines the types and number of components that can be installed. Example: a technician planning to add a second memory module to an office computer first checks that the motherboard has a free slot of the right type.

• Form factors: ATX, Micro-ATX, and Mini-ITX sizes affect expandability and case compatibility.
• Chipset: Controls communication between CPU, memory, and peripherals, influencing performance and features.
• Socket type: Must match the CPU model, impacting upgrade paths.
• Memory slots: Number and type of RAM slots determine maximum memory capacity.
• Expansion slots: PCIe slots allow installation of graphic cards, network cards, and other add-ons.

Video cards (graphics processing units)

Video cards handle rendering of images, video, and graphical data. Their selection depends on intended use, such as basic office tasks or high-end graphical applications. Example: a reception computer showing documents needs only integrated graphics, while a workstation used for drawing building plans benefits from a dedicated card.

• Integrated vs dedicated: Integrated GPUs share system memory with the CPU and are sufficient for general office use, while dedicated cards have their own memory for demanding tasks.
• Memory size and type: More VRAM supports higher resolution and complex graphics processing.
• Connectivity: Ports like HDMI, DisplayPort, and DVI ensure compatibility with monitors.
• Cooling solutions: Active cooling with fans is necessary for high-performance cards to prevent overheating.
• Driver support: Compatibility with operating systems and software used in firms such as architecture practices is essential.

Processor (CPU)

The processor is the part of the computer that carries out instructions, and it largely sets the speed of the whole system. It sits in a socket on the motherboard under a heat sink and fan. Example: a school examinations office processing results for thousands of learners needs a processor that can handle spreadsheets and database queries without long delays.

• Clock speed: Measured in gigahertz (GHz), it indicates how many cycles the processor performs each second.
• Core count: More cores allow several tasks to run at the same time, which helps with multitasking.
• Socket compatibility: The processor must fit the motherboard socket and be supported by its chipset.
• Cache memory: A small, very fast memory inside the processor that reduces waiting for data from RAM.
• Cooling requirement: Faster processors produce more heat and need a suitable heat sink and fan.

Memory modules (RAM)

Random access memory holds the programs and data the computer is using at the moment. It is much faster than storage drives but loses its contents when power is switched off. Example: a farm office running accounting software and a web browser together slows down noticeably if the computer has too little RAM.

• Capacity: Measured in gigabytes; the more RAM installed, the more programs can run smoothly together.
• Type and generation: Modules such as DDR4 and DDR5 are not interchangeable, and the motherboard accepts only one type.
• Speed: Faster modules transfer data more quickly, provided the motherboard and processor support the speed.
• Form factor: Desktop computers use full-size DIMM modules, while laptops use the shorter SO-DIMM modules.
• Slot count: The number of slots on the motherboard limits how much memory can be installed.

Power supply unit (PSU)

The PSU converts electrical power to the appropriate voltages for computer components. Selecting a reliable PSU safeguards hardware and ensures stable operation. Example: a computer in a small business that restarts whenever a second drive is added may have a PSU whose wattage is too low.

• Wattage rating: Must meet or exceed the total power consumption of components.
• Efficiency certification: Ratings like 80 Plus indicate energy efficiency, reducing electricity costs in offices.
• Modular vs non-modular: Modular PSUs allow customisable cable connections, improving airflow.
• Protection features: Over-voltage, under-voltage, and short-circuit protections prevent hardware damage.
• Form factor compatibility: Should fit the computer case and match motherboard power connectors.

Device compatibility

Compatibility ensures that hardware components and peripherals function seamlessly together. For instance, the choice of motherboard must support the CPU type and memory modules intended for use in a technical training institute's computer lab. Incompatibility can lead to system instability or hardware damage.

Performance specifications

Performance specifications such as processor speed, memory capacity, and storage type dictate the computer's ability to handle applications. In a pharmacy chain, high-performance machines are necessary for running stock management software without delays.

Working environment and usage

The environment where the computer operates affects hardware selection. Dusty or humid conditions in agricultural cooperatives require rugged cases and cooling solutions to prolong hardware life. Usage patterns, such as heavy multitasking in a microfinance institution, demand higher specifications.

Chapter Summary

This chapter provides a comprehensive overview of managing computer hardware devices, beginning with the selection and identification of essential components such as the computer case, monitor, keyboard, and mouse. It explains the internal parts of a computer including the hard disk drive, motherboard, and video cards, and classifies various hardware devices. The process of safely disassembling computer hardware is covered alongside the importance of cleaning these devices to maintain optimal performance. Assembly procedures are detailed, highlighting the types of hardware devices, their functions, and the correct methods for connecting peripherals like monitors and system units. The chapter also introduces the concept of booting, distinguishing between cold and warm booting techniques. Finally, it addresses the connection and configuration of peripheral devices, including mice, keyboards, and projectors, ensuring proper integration with the computer system.