Computer Hardware, Operating Systems and Databases: Key Concepts Explained

 System Hardware & Software Architecture

1.1.1 Computer Hardware: Internal Components and the Input–Process–Output Model

A computer can be understood as an Input → Process → Output (I-P-O) system: it accepts raw data, works on it, and produces a result.

• Input Unit: devices that feed data and instructions into the computer, e.g. keyboard, mouse, scanner.
• Central Processing Unit (CPU): the “brain” of the computer; it fetches, decodes and executes instructions. It has three main parts — the Control Unit, the Arithmetic Logic Unit and the Registers.
  • Control Unit (CU): directs and coordinates the activities of all other units; it does not process data itself.
  • Arithmetic Logic Unit (ALU): performs arithmetic operations (+, −, ×, ÷) and logical/comparison operations (AND, OR, NOT, >, <, =).
  • Registers: very small, very fast memory locations inside the CPU that temporarily hold the data or instruction currently being worked on.
• Primary Memory: RAM (Random Access Memory) is volatile working memory that is cleared when power is switched off; ROM (Read Only Memory) is non-volatile and permanently stores start-up instructions (firmware).
• Secondary Storage: non-volatile, larger-capacity, slower storage that keeps data permanently, e.g. Hard Disk Drive (HDD), Solid State Drive (SSD), USB flash drive.
• Output Unit: devices that present the processed result to the user, e.g. monitor, printer, speaker.

Other key internal components: the Motherboard is the main circuit board that physically connects the CPU, memory and other components; buses are electrical pathways that carry data (data bus), memory addresses (address bus) and instructions/timing signals (control bus) between them; and the Power Supply Unit (PSU) converts mains electricity into the low voltages the components need.

Utility Software

Utility software is a category of system software designed to analyse, configure, optimise or maintain a computer, keeping it running smoothly. Unlike the OS, a utility program performs one specific maintenance task rather than running the whole system.

• Antivirus software: detects and removes malicious programs (viruses, malware).
• Disk clean-up / defragmentation tools: free up storage space and organise files for faster access.
• File compression tools (e.g. ZIP): reduce file size for storage or transfer.
• Backup software: creates copies of data to protect against loss.

Peripheral Devices and Peripheral Management

A peripheral is any hardware device connected to a computer that is not part of its core internal architecture (i.e. not the CPU, motherboard or primary memory). Peripherals are generally classified as follows:

• Input peripherals: Keyboard, mouse, scanner, microphone, webcam
• Output peripherals: Monitor, printer, speaker, projector
• Storage peripherals: External hard disk, USB flash drive, memory card

Peripheral management is handled by the operating system through small control programs called device drivers, which translate general OS commands into the specific instructions a device understands. Modern systems also support Plug and Play (PnP), a feature that automatically detects a newly connected peripheral and loads (or prompts for) the correct driver, so the device can be used with little or no manual setup. Devices connect through standard ports such as USB, HDMI, Ethernet and audio jacks.

Operating System: Key Functions

The Operating System (OS) is system software that acts as an interface between the user, application programs and computer hardware. Its main functions are:

• Process management: schedules the CPU’s time among multiple running programs.
• Memory management: allocates and frees RAM space as programs start and stop.
• File management: organises data using a file structure — a hierarchy of drives, folders (directories) and files — and controls how they are named, stored and retrieved.
• Device management: controls input/output devices through device drivers, as described above.
• Security & access control: manages user accounts, login passwords and file permissions.

Cloud Service Models

Pivot Tables and Data Visualisation

2.4 Introduction to Databases

A relational database stores data in one or more related tables, each of which is formally called a relation.