Introduction to Computer Hardware

What is a Computer?

• A computer is an electronic device that accepts data as input.
• It processes data using a set of instructions.
• It produces meaningful results as output.
• Computers store, retrieve, and process data.
• They employ a combination of hardware and software.

Computer Hardware

• This refers to the physical components of a computer system.
• Components include the processor (CPU), memory, storage, input/output, and peripherals.
• Hardware provides a platform for running software applications.
• Consists of various mechanical, electrical, and electronic components.
• Hardware components can be classified as internal and external.
• Internal Components: Motherboard, CPU, CPU Heatsink, SMPS, RAM, Graphics Card, Hard Disks/Disk Memory.
• External Components: Computer Case, Connection Sockets, Computer Display Monitor, Computer Keyboard, Computer Mouse, Printer & Power Supply Cable, External USB Hard Disks.

Functions of Hardware Components

• Computer Case/Cabinet: A metal enclosure for organizing and assembling internal hardware components.
• Motherboard: The largest printed circuit board, acts as a central hub connecting all hardware components. It manages data flow and power allocation.

CPU (Processor)

• The CPU is responsible for executing most commands.
• 'Clock speed' measures the speed at which it does this (in GHz).
• Key components include ALU (Arithmetic Logic Unit) and the Control Unit (CU).
  • ALU performs arithmetic and logical operations.
  • CU manages data flow and directs CPU operations.
• Registers are small, fast memory units for temporary data storage.
• Cache memory stores frequently used data close to the CPU for quicker access.
• Buses facilitate communication among the CPU and other components (e.g., data bus, address bus, control bus).
• A Clock synchronizes operations.

Power Supply Unit (PSU)

• Supplies stable electrical power.
• Converts AC to DC electricity.
• Standard desktop computer's power cord connects to the PSU.

Memory Unit (RAM)

• Stores data, instructions, and information.
• RAM is essential for fast data access for immediate processing.
• RAM is temporary storage, erased when the computer is turned off.
• There exist various types of computer memory (e.g., DRAM, SRAM).

Read-Only Memory (ROM)

• Stores firmware or software instructions.
• Non-volatile memory—data remains stored even when power is off.
• ROM is used during the computer booting or bootstrapping process.

Types of ROM (ROM chips):

• PROM: Programmable Read-Only Memory, written to once.
• EPROM: Erasable Programmable Read-Only Memory, rewritten with UV light.
• EEPROM: Electrically Erasable Programmable Read-Only Memory, rewritten with an electric charge.
• Flash Memory: Re-writable; often used in mobile devices and flash drives.

Secondary Memory (HDD/SSD)

• Long-term storage for digital content, operating system, and programs.
• HDD is a traditional hard disk drive that's slower than SSD.
• SSD is a newer form of long-term storage that uses flash memory and is faster and more reliable than HDD.

Graphics Card (GPU)

• Processes images and videos to display on the computer monitor.
• Processes images for presentation.

Ports

• Ports are connection points that extend the functionality of a computer by connecting devices.

Computer Software

• A set of instructions that direct the computer's operations.
• Software is categorized as System and Application Software.
• System Software: Manages core functions, allows application software to operate, manages hardware resources (e.g., operating systems, utilities, etc.)
• Application Software: Application software performs tasks for the user (e.g., word processors).

Utility Software

• Essential for computer maintenance.
  • Example: antivirus, disk cleanup tools, system optimizers.

Device Drivers

• Specialized software allowing an operating system to communicate with hardware.
• They act as a bridge between the OS and the hardware components or devices.

BIOS

• The basic input/output system program that a computer's microprocessor uses to start the computer system.
• Controls the flow of data between the OS and attached peripheral devices.

UEFI

• Unified Extensible Firmware Interface.
• More modern firmware interface, replacing BIOS.

Operating System

• An interface between users and hardware.
• Manages resources, CPU, file management.
• Makes the computer system more convenient and efficient.

Program/Process/Thread

• Program: A set of instructions.
• Process: The set of instructions in execution (active program).
• Thread: A single sequence of control within a program.

Types of Operating Systems

• Single-Processor OS: Manages a system with a single CPU.
• Batch OS: Processes groups of similar jobs without interaction.
• Multiprogramming OS: Executes multiple programs on a single processor; utilizes the CPU efficiently when one program waits on input/output operations.
• Multitasking/Time-Sharing OS: Allows multiple tasks to execute concurrently (or on the same processor).
• Multiprocessing OS: Uses multiple CPUs to improve performance by processing tasks in parallel.
• Distributed OS: Multiple computer systems communicate through a single communication channel.
• Real-Time OS: Processes data and tasks within strict time constraints (e.g. Air Traffic Control).

Kernel Space/User Space

• Kernel Space: A protected area of memory where the "kernel" works.
• Kernel: Responsible for everything (e.g., scheduling processes, managing memory, and handling interrupts); has complete control over the system.
• Kernel provides functions that are essential for the operating system.
• User Space: User-facing applications and processes operate here.
• User-mode application cannot directly access hardware resources and must use system calls to access the kernel.

System Call Interface (SCI)

• Acts like a receptionist.
• Facilitates communication between user applications and kernel.

Interrupts

• A signal sent to the processor to indicate an event.
• Can temporarily halt the current task ensuring efficient operation.
• Interrupt Service Routine (ISR) is executed in response.

Types of Kernels

• Monolithic kernel: Combines core OS functionality in a single memory space, and enables faster process execution.
• Microkernel: Contains only essential services and separates user and kernel services in distinct memory spaces, reduces OS size.
• Hybrid kernel: Combines characteristics of both monolithic and microkernels.

IPC (Interprocess Communication)

• Medium of conversion between user mode and kernel mode.
• Methods include Message Passing and Shared Memory.

Malware

• Any software designed to harm, exploit, or compromise devices, networks, or data.

Types of Attackers

• Amateurs: Script kiddies (inexperienced hackers, use pre-made tools).
• Hackers: White hat (identify and report vulnerabilities, usually have permission), Gray hat, Black hat (take advantage of vulnerabilities for personal gain), Organised Hackers (State-sponsored, Terrorist groups).

Cyber Warfare

• Use of technology to attack another nation's computer systems.

Computer Viruses

• Malicious software that spreads between computers.
• Can disrupt operations, cause data loss, crash systems, and security breaches.

Worms

• Self-replicating malware, automatically spreads to other computers, causing disruption.

Denial of Service Attacks (DoS/DDoS)

• Malicious attempts to overload a network, preventing legitimate access.
• Types include DoS and DDoS (distribute denial of service).

Interception

• Capture of information in transit between computers or devices.
• Improper encryption leaves information vulnerable to misuse.

Man-in-the-Middle Attack

• Attacker secretly intercepts communications between two parties.
• Modifies messages or data, without the parties' knowledge.

Phishing

• Pretending to be someone/something to gain sensitive data like passwords.
• Example: sending fraudulent emails or messages.
• Types: Phishing, Spear Phishing, CEO Fraud (or Whaling), Smishing, Vishing.

Pretexting

• Making false claims to gain sensitive information from people. (e.g., impersonating a bank worker or social worker)

Tailgating/Social Engineering

• Exploits trust and social connections, may include pretending to be someone you know.
  • Example: Following someone into a building or gaining access physically/digitally in person.

Cryptocurrency

• A digital currency, using encryption algorithms.
• Functioning as both a currency and virtual accounting system.

Security Architecture

• Strategic design of systems, policies, and technologies to protect IT and business assets from cyber threats.

Risk Assessment

• Identifying potential security gaps and cyber threats.
• Determining how well the organization addresses those threats.

Threat Intelligence

• Analysis of data to generate meaningful information about emerging threats.
• Helping anticipate or mitigate cyber threats.

Security Operations (SecOps)

• Integrating security measures and processes for enhanced cyber resiliency within an IT operation.

GRC (Governance, Risk, and Compliance)

• Structured way to align IT with business goals, manage risks, and ensure compliance.
• Unification of the company's governance, risk management, technological innovation, and compliance efforts.