Chapter 3: Hardware – (0478/2210) IGCSE/GCE CS Notes

Based on Cambridge Syllabus 2026-2028

What is Hardware?

Hardware refers to the tangible, physical parts of a computer system. These are the components you can see and touch.

Hardware includes:

Input devices – Send data into the computer
Output devices – Display or present data from the computer
Storage devices – Store data permanently or temporarily
Processors – Execute instructions and process data (e.g., CPU)
Peripherals – External devices connected to the computer

Hardware works together with software (programs and data) to perform operations.

Computer Architecture

The Role of the CPU

The Central Processing Unit (CPU) is the brain of the computer. Its role is to:

Process instructions and data that are input into the computer
Perform calculations and logical operations
Control the flow of data between different components
Ensure that results can be output to the user

What is a Microprocessor?

A microprocessor is a type of integrated circuit on a single chip that contains the functions of a CPU.

Key point: All CPUs are microprocessors, but not all microprocessors are called CPUs (they can be found in embedded systems, calculators, etc.)

The CPU and Its Components

Von Neumann Architecture

Most computers use the Von Neumann architecture, where:

Data and instructions are stored in the same memory
The CPU fetches instructions and data from memory
Instructions are executed sequentially

CPU Components

The CPU consists of three main types of components: units, registers, and buses.

1. Units

Unit	Full Name	Function
ALU	Arithmetic Logic Unit	Performs arithmetic calculations (+, -, ×, ÷) and logical operations (AND, OR, NOT, comparisons)
CU	Control Unit	Directs the flow of data, controls instruction execution, sends control signals to other components

2. Registers

Registers are small, high-speed storage locations within the CPU that temporarily hold data and instructions during processing.

Register	Full Name	Purpose
PC	Program Counter	Holds the memory address of the next instruction to be executed
MAR	Memory Address Register	Holds the address of memory location currently being read from or written to
MDR	Memory Data Register	Holds the actual data or instruction being transferred to or from memory
CIR	Current Instruction Register	Holds the current instruction being executed
ACC	Accumulator	Stores intermediate results of arithmetic and logic operations

3. Buses

Buses are communication pathways that transfer data and signals between components.

Bus	Purpose	Direction
Address Bus	Carries memory addresses from CPU to memory	Unidirectional (CPU → memory)
Data Bus	Carries actual data between CPU, memory, and I/O	Bidirectional
Control Bus	Carries control signals (read/write commands)	Bidirectional

Visual Representation of CPU Components

                         ┌─────────────────────┐
                         │         CPU          │
                         │  ┌─────────────────┐ │
                         │  │      CU         │ │
                         │  │                 │ │
                         │  └────────┬────────┘ │
                         │            │          │
                         │  ┌─────────▼────────┐ │
                         │  │      ALU         │ │
                         │  │                  │ │
                         │  └─────────────────┘ │
                         │                       │
                         │  ┌─────────────────┐ │
                         │  │   REGISTERS     │ │
                         │  │ PC  MAR  MDR    │ │
                         │  │ CIR  ACC        │ │
                         │  └─────────────────┘ │
                         └───────────┬───────────┘
                                     │
              ┌──────────────────────┼──────────────────────┐
              │                      │                      │
         Address Bus            Data Bus               Control Bus
              │                      │                      │
              ▼                      ▼                      ▼
         ┌──────────┐          ┌──────────┐          ┌──────────┐
         │  MEMORY  │          │   I/O    │          │  OTHER   │
         │  (RAM)   │          │ DEVICES  │          │COMPONENTS│
         └──────────┘          └──────────┘          └──────────┘

The Fetch-Decode-Execute Cycle

The FDE cycle is the process by which the CPU retrieves an instruction from memory, interprets it, and carries it out.

Step 1: Fetch

The CPU fetches an instruction from memory (RAM).

Component	Role in Fetch Stage
PC	Holds address of next instruction
MAR	Address from PC is copied into MAR
Address Bus	Carries address from MAR to RAM
Control Bus	Sends “read” signal to memory
RAM	Returns instruction at that address
Data Bus	Carries instruction from RAM to CPU
MDR	Receives and holds the instruction
CIR	Instruction copied from MDR to CIR
PC	Incremented to point to next instruction

Step 2: Decode

The CPU interprets the instruction to understand what needs to be done.

Component	Role in Decode Stage
CIR	Holds the instruction to be decoded
CU	Decodes the instruction in CIR
CU	Determines what operation is needed (e.g., ADD, LOAD)
CU	Identifies what data is needed and where it’s located

Step 3: Execute

The CPU carries out the instruction.

Component	Role in Execute Stage
CU	Sends control signals to appropriate components
ALU	Performs any calculations or logical operations needed
ACC	Stores results of calculations
MAR/MDR	May be used to read or write data from memory
Buses	Carry data and addresses as needed

Visual Summary of FDE Cycle

┌─────────────────┐
│     FETCH       │
│ PC → MAR        │
│ Address Bus → RAM│
│ RAM → Data Bus  │
│ Data Bus → MDR  │
│ MDR → CIR       │
│ PC increments   │
└────────┬────────┘
         │
         ▼
┌─────────────────┐
│     DECODE      │
│ CU decodes      │
│ instruction in  │
│ CIR             │
└────────┬────────┘
         │
         ▼
┌─────────────────┐
│     EXECUTE     │
│ ALU performs    │
│ operation       │
│ Results stored  │
│ in ACC/memory   │
└────────┬────────┘
         │
         ▼
    Repeat cycle

Example: Adding Two Numbers

Instruction: ADD 5, 3

Stage	What Happens
Fetch	CPU fetches the ADD instruction from memory
Decode	CU decodes that this is an ADD operation requiring two numbers
Execute	ALU adds the numbers (5 + 3 = 8), result stored in ACC

CPU Performance Factors

Three main factors affect how fast a CPU can process instructions:

1. Number of Cores

Term	Definition
Core	An individual processing unit within the CPU that can execute instructions independently

How it affects performance:

More cores allow the CPU to execute multiple instructions simultaneously
Dual-core = 2 instructions at once, Quad-core = 4 instructions at once
Improves multitasking and parallel processing

Limitation: Software must be designed to use multiple cores (parallel processing)

2. Cache Size

Term	Definition
Cache	Small, very fast memory inside the CPU that stores frequently used data and instructions

Levels of cache:

L1 cache – Smallest, fastest, inside each core
L2 cache – Larger, slightly slower than L1
L3 cache – Largest, shared between cores

How it affects performance:

Larger cache means more data can be stored close to the CPU
Reduces need to access slower RAM
Speeds up processing by having data ready when needed

3. Clock Speed

Term	Definition
Clock	A timing device that synchronises CPU operations
Clock speed	Number of cycles the CPU can execute per second (measured in GHz)

How it affects performance:

Higher clock speed = more instructions per second
3 GHz = 3 billion cycles per second
Each cycle can execute one or more instructions

Comparison Table

Factor	What it does	Impact on Performance
More cores	Executes multiple instructions simultaneously	Better for multitasking and parallel tasks
Larger cache	Stores more data close to CPU	Reduces waiting for data from RAM
Higher clock speed	More cycles per second	Faster execution of instructions

Instruction Sets

What is an Instruction Set?

An instruction set is a list of all the commands that a CPU can understand and execute.

Key points:

Each CPU model has its own instruction set
Instructions are in machine code (binary)
Different CPUs may have different instruction sets (e.g., x86, ARM)

What Instructions Are Included?

Typical instruction set categories:

Category	Examples
Data transfer	LOAD, STORE, MOVE
Arithmetic	ADD, SUBTRACT, MULTIPLY, DIVIDE
Logic	AND, OR, NOT, COMPARE
Control flow	JUMP, BRANCH, CALL, RETURN

Why Instruction Sets Matter

Determines what operations the CPU can perform
Software must be compiled for a specific instruction set
Complex instruction sets can do more in fewer steps
Simpler instruction sets may be faster but need more steps

Embedded Systems

What is an Embedded System?

An embedded system is a computer system designed to perform one or a few dedicated functions, often with real-time computing constraints.

Key characteristics:

Performs a dedicated function
Part of a larger device
Has limited hardware resources
Often runs a single program repeatedly

Embedded Systems vs General Purpose Computers

Feature	Embedded System	General Purpose Computer
Purpose	Single dedicated function	Many different functions
User interaction	Minimal (buttons, sensors)	Extensive (keyboard, mouse, screen)
Software	Fixed, stored in ROM	Can install new software
Examples	Microwave, car, thermostat	PC, laptop, tablet

Common Devices with Embedded Systems

Category	Examples
Domestic appliances	Washing machines, microwaves, refrigerators
Cars	Engine control units, braking systems, infotainment
Security systems	Burglar alarms, CCTV, smart locks
Lighting systems	Smart bulbs, automatic street lights
Vending machines	Drink dispensers, ticket machines
Medical devices	Pacemakers, glucose monitors
Industrial control	Factory robots, assembly lines

Advantages of Embedded Systems

Low cost to manufacture
Low power consumption
Reliable for dedicated tasks
Small physical size
No user intervention needed

Input Devices

What is an Input Device?

An input device is hardware that allows users to send data or instructions into a computer system.

Common Input Devices

Device	Description	Example Use
Keyboard	Standard text input with keys	Typing documents, coding
Mouse	Pointer control device	Navigating GUI, selecting items
Touchscreen	Combines input and output via touch	Smartphones, tablets, kiosks
Microphone	Captures sound input	Voice commands, recording, calls
Digital camera	Captures images and video	Photography, video calls
Barcode scanner	Reads barcode patterns	Retail checkout, inventory
QR code scanner	Reads QR codes (2D barcodes)	Payment, tickets, information
Optical mouse	Uses light to detect movement	Computer navigation
2D scanner	Flattens documents to digital images	Archiving, OCR
3D scanner	Creates 3D digital models of objects	Manufacturing, design

Touchscreen Technologies

Type	How it Works	Advantages	Disadvantages
Resistive	Pressure causes two layers to touch	Works with any object (finger, stylus), cheap	Less sensitive, lower clarity
Capacitive	Electrical conductivity of finger changes capacitance	Very sensitive, multi-touch, clear	Only works with conductive objects (no glove)
Infra-red	Grid of IR beams detects interruption	Works with any object, durable	Expensive, affected by direct sunlight

Output Devices

What is an Output Device?

An output device is hardware that allows a computer to communicate information to the user.

Common Output Devices

Device	Description	Example Use
Monitor (VDU)	Displays visual output	Browsing, gaming, work
LED screen	Uses light-emitting diodes	TVs, displays, signs
LCD screen	Uses liquid crystals	Monitors, laptops, calculators
Printer (Inkjet)	Sprays ink onto paper	Home printing, photos
Printer (Laser)	Uses toner and static electricity	Office printing, high volume
3D printer	Creates physical 3D objects	Prototyping, manufacturing
Speaker	Outputs sound	Audio playback, alerts
Projector (LCD)	Passes light through LCD panel	Presentations, classrooms
Projector (DLP)	Uses tiny mirrors to reflect light	Home cinema, large venues
Actuator	Produces physical movement	Robotics, automated systems

Printer Comparison

Feature	Inkjet Printer	Laser Printer
Technology	Sprays liquid ink	Uses toner powder and heat
Speed	Slower	Faster
Quality	Good for photos	Good for text
Cost per page	Higher	Lower
Initial cost	Lower	Higher
Best for	Home use, photos	Office use, text documents

Sensors

What is a Sensor?

A sensor is an input device that detects physical changes in the environment and converts them into electrical signals that a computer can process.

Types of Sensors

Sensor	Detects	Example Use
Acoustic	Sound waves	Noise monitoring, burglar alarms
Accelerometer	Acceleration, movement	Smartphone orientation, step counters
Flow	Rate of fluid flow	Water meters, fuel systems
Gas	Presence of gases	Carbon monoxide detectors, leak detection
Humidity	Moisture in air	Weather stations, greenhouses
Infra-red	Heat signatures	Motion detectors, thermal imaging
Level	Height of liquid	Tank filling systems, reservoirs
Light	Light intensity	Street lights, camera exposure
Magnetic field	Magnetic fields	Compass, metal detectors
Moisture	Water content	Soil moisture for irrigation
pH	Acidity/alkalinity	Water quality, soil testing
Pressure	Force applied	Touch screens, weather forecasting
Proximity	Presence of nearby objects	Parking sensors, phone screen off
Temperature	Heat/cold levels	Thermostats, ovens, weather

Choosing the Right Sensor

Scenario	Appropriate Sensor
Automatic doors	Proximity or infra-red sensor
Greenhouse watering	Moisture sensor + temperature sensor
Weather station	Temperature, humidity, pressure, light
Car parking assist	Proximity (ultrasonic) sensors
Smoke alarm	Gas sensor, smoke detector

Primary Storage

What is Primary Storage?

Primary storage is memory that is directly accessed by the CPU. It holds data and instructions that are currently in use.

RAM (Random Access Memory)

Feature	Description
Volatility	Volatile – loses data when power is off
Purpose	Stores running programs and current data
Speed	Fast access
Read/Write	Can be read from and written to

Role of RAM:

Holds the operating system while computer is running
Stores applications currently open
Holds data being processed
Provides fast access for CPU

ROM (Read Only Memory)

Feature	Description
Volatility	Non-volatile – retains data when power is off
Purpose	Stores essential startup instructions
Speed	Slower than RAM
Read/Write	Usually read-only (cannot be changed easily)

Role of ROM:

Stores BIOS/UEFI (firmware)
Contains bootloader instructions
Performs Power-On Self-Test (POST)
Initialises hardware when computer starts

Why Computers Need Both RAM and ROM

Situation	RAM	ROM
When computer starts	Empty	Contains boot instructions
During normal operation	Holds OS and apps	Not used
When running programs	Stores program data	Not used
When power is off	Data lost	Boot instructions preserved

Comparison: RAM vs ROM

Feature	RAM	ROM
Volatility	Volatile	Non-volatile
Data retention	Lost on power off	Retained on power off
Speed	Fast	Slower
Content	Changes constantly	Fixed (factory programmed)
Purpose	Temporary storage	Permanent instructions
Size	Large (GB)	Small (MB)

Secondary Storage

What is Secondary Storage?

Secondary storage is storage that is not directly accessed by the CPU. It is used for more permanent storage of data when the computer is turned off.

Types of Secondary Storage

1. Magnetic Storage

How it works:

Uses magnetic platters divided into tracks and sectors
Read/write head uses electromagnets to magnetise particles
Data stored as magnetic patterns

Example: Hard Disk Drive (HDD)

Characteristics:

Large capacity
Relatively cheap per GB
Moving parts (slower, less durable)
Susceptible to physical shock

2. Optical Storage

How it works:

Uses lasers to create and read pits (indentations) and lands (flat areas)
Laser reflects differently from pits and lands
Data stored as patterns of reflections

Examples: CD, DVD, Blu-ray

Characteristics:

Removable media
Durable against magnetic fields
Slower than magnetic or solid-state
Limited capacity (compared to HDD)

Format	Capacity	Use
CD	700 MB	Music, software
DVD	4.7 GB (single layer)	Movies, games
Blu-ray	25 GB (single layer)	HD movies, backups

3. Solid-State Storage (Flash Memory)

How it works:

Uses NAND or NOR technology
Transistors with control gates and floating gates
Electrons trapped in floating gate represent data (0 or 1)
No moving parts

Examples: SSD (Solid State Drive), USB flash drive, SD card

Characteristics:

Very fast access
No moving parts (durable, silent)
Lower power consumption
More expensive per GB than magnetic
Limited write cycles (wear leveling used)

Comparison of Secondary Storage Types

Feature	Magnetic (HDD)	Optical (CD/DVD)	Solid-State (SSD)
Speed	Medium	Slow	Very fast
Capacity	High	Low to medium	Medium to high
Cost per GB	Low	Low	Higher
Durability	Low (moving parts)	Medium	High (no moving parts)
Portability	Internal mostly	High	High
Power use	Medium	Low (when reading)	Very low

Virtual Memory

What is Virtual Memory?

Virtual memory is a section of secondary storage (hard drive or SSD) that is used as if it were RAM when the physical RAM is full.

Why is Virtual Memory Needed?

RAM is limited and expensive
Programs may require more memory than physically available
Allows multiple large programs to run simultaneously

How Virtual Memory Works

When RAM becomes full, the OS identifies less frequently used data
This data is paged (moved) from RAM to virtual memory on the hard drive
The RAM space is freed up for active programs
If the paged data is needed again, it is swapped back into RAM
This process is called paging or swapping

┌─────────────────┐
│      RAM        │
│  ┌───────────┐ │
│  │ Active    │ │
│  │ Program A │ │
│  └───────────┘ │
│  ┌───────────┐ │
│  │ Active    │ │◄───┐
│  │ Program B │ │    │
│  └───────────┘ │    │
│  ┌───────────┐ │    │ When RAM full
│  │ Inactive  │ │    │
│  │ Data      │ │    │
│  └───────────┘ │    │
└─────────────────┘    │
         │             │
         │ Page out    │
         ▼             │
┌─────────────────┐    │
│ VIRTUAL MEMORY  │    │
│ (Hard Drive)    │    │
│  ┌───────────┐ │    │
│  │ Paged out │ │◄───┘
│  │   Data    │ │
│  └───────────┘ │
│                │
└─────────────────┘

Advantages and Disadvantages

Advantages	Disadvantages
Allows running more programs than RAM can hold	Slower than RAM (hard drive is slower)
Prevents programs from crashing due to low memory	Excessive paging (thrashing) slows system
Cost-effective way to extend memory	Uses space on secondary storage

Cloud Storage

What is Cloud Storage?

Cloud storage is a model where data is stored on remote servers accessed via the internet, rather than locally on personal devices.

Key point: Physical servers and storage are still needed – they are just located elsewhere and managed by a provider.

How Cloud Storage Works

User Device
     │
     │ Internet
     ▼
┌─────────────────────┐
│   Cloud Provider     │
│  ┌─────────────────┐ │
│  │  Data Center    │ │
│  │  ┌───────────┐ │ │
│  │  │ Servers   │ │ │
│  │  │ Storage   │ │ │
│  │  └───────────┘ │ │
│  └─────────────────┘ │
└─────────────────────┘

Cloud Storage vs Local Storage

Aspect	Cloud Storage	Local Storage
Access	Anywhere with internet	Only on that device or network
Cost	Monthly subscription	One-time purchase
Maintenance	Handled by provider	User responsible
Security	Provider handles	User handles
Backup	Automatic	Manual
Speed	Depends on internet	Fast (direct connection)
Capacity	Scalable (pay for more)	Fixed by hardware

Advantages of Cloud Storage

Accessible anywhere – Files available from any device with internet
Automatic backup – Data backed up by provider
Scalability – Easy to increase storage space
No hardware maintenance – Provider manages servers
Collaboration – Multiple users can access and edit shared files
Disaster recovery – Data safe if local device fails

Disadvantages of Cloud Storage

Requires internet connection – Cannot access without internet
Ongoing cost – Subscription fees can add up
Security concerns – Data stored on someone else’s servers
Privacy issues – Provider could access data
Speed dependent – Upload/download limited by connection
Data sovereignty – Data may be stored in different countries with different laws

Network Hardware

Network Interface Card (NIC)

A Network Interface Card (NIC) is hardware that allows a computer to connect to a network.

Key points:

Every NIC has a unique MAC address at the point of manufacture
Can be wired (Ethernet) or wireless (Wi-Fi)
Required for any device to access a network

MAC Address

Aspect	Description
Full name	Media Access Control address
Purpose	Unique identifier for network device
Length	48 bits (12 hexadecimal digits)
Format	Usually written as 6 pairs: 00:1A:2B:3C:4D:5E
Assignment	Factory-assigned to NIC (hardware address)
Uniqueness	Globally unique

Structure of MAC Address:

First 6 hex digits = Manufacturer code (OUI)
Last 6 hex digits = Serial number assigned by manufacturer

Example: 00:1A:2B:3C:4D:5E

00:1A:2B = Manufacturer (e.g., Intel)
3C:4D:5E = Unique serial number

IP Address

Aspect	Description
Full name	Internet Protocol address
Purpose	Identifies device on a network
Assignment	Allocated by network (software address)
Uniqueness	Must be unique on that network

Types of IP Address

Type	Description
Static IP	Permanently assigned to a device, never changes
Dynamic IP	Temporarily assigned from a pool, may change each connection

IPv4 vs IPv6

Feature	IPv4	IPv6
Address length	32 bits	128 bits
Format	Four decimal numbers (0-255) separated by dots	Eight hexadecimal groups separated by colons
Example	192.168.1.1	2001:0db8:85a3:0000:0000:8a2e:0370:7334
Number of addresses	~4.3 billion	340 undecillion (virtually unlimited)
Status	Being exhausted	Growing adoption

Router

A router is a device that forwards data packets between computer networks.

Role of a router:

Sends data to specific destinations on a network
Connects a local network to the internet
Assigns IP addresses to devices on the local network (DHCP)
Directs traffic between devices
Provides firewall and security functions

How routers work:

Receives data packet
Examines destination IP address
Consults routing table
Forwards packet toward destination

Summary & Key Takeaways

CPU Components

Component	Function
ALU	Arithmetic and logic operations
CU	Controls instruction execution
Registers	Fast temporary storage (PC, MAR, MDR, CIR, ACC)
Buses	Communication pathways (address, data, control)

FDE Cycle

Fetch – Get instruction from memory
Decode – Interpret what to do
Execute – Carry out instruction

CPU Performance

More cores = parallel processing
Larger cache = faster data access
Higher clock speed = more cycles per second

Embedded Systems

Dedicated function devices
Examples: microwaves, cars, security systems

Input Devices

Keyboard, mouse, touchscreen, microphone, scanner, sensors

Output Devices

Monitor, printer, speaker, projector, actuator

Sensors

Detect physical quantities (temperature, light, pressure, moisture, etc.)

Primary Storage

	RAM	ROM
Volatile?	Yes	No
Purpose	Running programs	Boot instructions

Secondary Storage

Type	Technology	Examples
Magnetic	Magnetised platters	HDD
Optical	Pits and lands (laser)	CD, DVD, Blu-ray
Solid-state	Flash memory (transistors)	SSD, USB, SD card

Virtual Memory

Uses hard drive space as “extra RAM”
Slower but allows more programs to run

Cloud Storage

Remote servers accessed via internet
Advantages: anywhere access, automatic backup
Disadvantages: needs internet, ongoing cost

Network Hardware

Component	Purpose
NIC	Connects device to network
MAC address	Unique hardware identifier
IP address	Network location identifier
Router	Directs traffic between networks

Practice Questions

Section A: CPU Architecture

What is the role of the CPU in a computer system?
List three components inside a CPU and describe the function of each.
Explain the purpose of each of these registers:
a) Program Counter (PC)
b) Memory Address Register (MAR)
c) Accumulator (ACC)
Describe the three buses in a computer and state whether each is unidirectional or bidirectional.

Section B: Fetch-Decode-Execute Cycle

Describe what happens during the Fetch stage of the FDE cycle.
Explain the role of the Control Unit during the Decode stage.
During the Execute stage of adding two numbers, which component performs the calculation and where is the result stored?

Section C: CPU Performance

State three factors that affect CPU performance.
Explain how increasing the number of cores can improve performance.
What is cache memory and why is it important for CPU performance?
If a CPU has a clock speed of 3 GHz, how many cycles does it execute per second?

Section D: Embedded Systems

What is an embedded system?
Give three examples of devices that contain embedded systems.
Explain one difference between an embedded system and a general-purpose computer.

Section E: Input and Output Devices

State whether each of these is an input device, output device, or both:
a) Touchscreen
b) Speaker
c) Microphone
d) 3D printer
Describe two different touchscreen technologies and explain how they work.
Compare inkjet printers and laser printers. Give one advantage of each.

Section F: Sensors

What is a sensor?
Identify the most suitable sensor for each scenario:
a) Automatic greenhouse watering system
b) Car parking sensors
c) Weather station measuring air moisture
d) Automatic street lights
A farmer wants to monitor soil conditions. Suggest three different sensors they might use and explain what each would detect.

Section G: Primary Storage

Explain the difference between RAM and ROM.
Why does a computer need both RAM and ROM?
What happens to data in RAM when the computer is turned off? Why?

Section H: Secondary Storage

Describe how magnetic storage (HDD) stores data.
Explain the difference between pits and lands in optical storage.
Give two advantages of solid-state storage (SSD) over magnetic storage (HDD).
A photographer needs to store 500 GB of photos. Recommend a storage device and justify your choice.

Section I: Virtual Memory

What is virtual memory and why is it needed?
Explain the process of paging when RAM becomes full.
Give one advantage and one disadvantage of using virtual memory.

Section J: Cloud Storage

What is cloud storage?
Give two advantages and two disadvantages of storing data in the cloud compared to storing it locally.
A small business is considering moving from local storage to cloud storage. What factors should they consider?

Section K: Network Hardware

What is a MAC address and where is it stored?
Explain the difference between a static IP address and a dynamic IP address.
Compare IPv4 and IPv6 in terms of:
a) Address length
b) Number of possible addresses
c) Format
Describe three roles of a router in a network.

Quick Reference Card

Topic	Key Points
CPU components	ALU (calculations), CU (control), Registers (fast storage)
Registers	PC (next address), MAR (memory address), MDR (data), CIR (current instruction), ACC (results)
Buses	Address (addresses), Data (data), Control (signals)
FDE cycle	Fetch → Decode → Execute (repeats)
Performance	Cores (parallel), Cache (speed), Clock speed (cycles/sec)
Embedded system	Dedicated function (microwave, car, security)
Input devices	Keyboard, mouse, touchscreen, microphone, sensors
Output devices	Monitor, printer, speaker, projector, actuator
Sensors	Temperature, light, pressure, moisture, proximity, etc.
RAM	Volatile, running programs
ROM	Non-volatile, boot instructions
Magnetic storage	HDD (tracks/sectors, electromagnets)
Optical storage	CD/DVD/Blu-ray (pits/lands, laser)
Solid-state	SSD/USB/SD (flash memory, transistors)
Virtual memory	Hard drive space used as RAM
Cloud storage	Remote servers via internet
MAC address	Hardware ID (hexadecimal, unique)
IP address	Network location (static/dynamic)
Router	Directs traffic, connects networks, assigns IPs

End of Chapter 3: Hardware

Below is a a detailed presentation for this chapter that you can download to study from slides.

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