CPU and Microprocessor Fundamentals

CPU and Microprocessor

• A CPU (Central Processing Unit) processes data by executing instructions
• A microprocessor is a type of integrated circuit that contains a CPU, used in general-purpose computers and embedded systems

Components of a CPU

• Control Unit:
  • Controls the flow of data around the CPU
  • Sends control signals to different components
  • Decodes instructions
  • Controls the timings of operations
• Arithmetic Logic Unit (ALU):
  • Performs calculations required to execute instructions (e.g., ADD, SUBTRACT)
  • Carries out logical operations (e.g., COMPARE)
  • Has a built-in register for interim results
• Registers and Buses:
  • Registers: small memory locations within the CPU that temporarily store data needed to execute an instruction
  • Program Counter (PC): stores the address of the next instruction to be fetched
  • Memory Address Register (MAR): stores the address of the instruction or data to be fetched or written to memory
  • Memory Data Register (MDR): stores the data that has been fetched from memory or is being written to memory
  • Current Instruction Register (CIR): stores the instruction being decoded or executed
  • Accumulator: temporarily stores the results of calculations performed by the ALU
• Buses: parallel transmission components that transmit data between components

System Buses

• Address bus: carries addresses throughout the computer system, unidirectional between CPU and memory
• Data bus: carries data between CPU, memory, and input/output devices, bidirectional
• Control bus: carries control signals between CPU and other components, bidirectional, 8-bits wide

Fetch-Decode-Execute Cycle

• FETCH: CPU fetches instruction from memory, stores it in MDR, and increments PC
• DECODE: instruction is decoded, and control signals are sent to components
• EXECUTE: CPU executes the instruction, using control signals to interact with components

Factors Affecting CPU Performance

• Cache memory: stores frequently accessed instructions and data, improving CPU performance
• Number of cores: more cores allow for more instructions executed per second
• Clock speed: increasing clock speed increases processing speed

Embedded Systems

• A computer system with a specific function, built into a larger mechanical device
• Runs on firmware, no additional peripherals
• Examples: digital clocks, traffic lights, security systems, vending machines

Advantages of Embedded Systems

• Low power consumption
• Small physical size
• Low cost to manufacture
• Can be controlled remotely
• Real-time operation and quick response to inputs

Input Devices

• Examples: barcode scanner, QR code scanner, 2D and 3D scanners, digital camera, keyboard, mouse, microphone, touchscreen

Output Devices

• Actuators: convert electrical signals to mechanical processes
• Examples: turning a wheel, opening/closing a door, controlling a conveyor belt
• Projectors: digital light projector (DLP), LCD projector
• Printers: laser printer, inkjet printer, 3D printer
• Display screens: LCD, LED, OLED### Organic Carbon Compounds and Semiconductors
• Organic carbon compounds are used to create semiconductors
• No backlighting is required for these semiconductors
• They can be made into very thin, flexible screens

Speakers

• Speakers are used to convert digital sounds or recordings into sound waves that can be heard by humans
• Typical uses of speakers include:
  • Listening to music
  • Listening to video sound
  • Telephone calls
  • Alarms

Sensors

• Sensors are input devices that measure physical properties of their environment
• Examples of physical properties that can be measured by sensors include:
  • Light levels
  • Temperature
  • Movement
• Sensors can be used for:
  • Monitoring systems
  • Control systems

Types of Sensors

• Acoustic sensors: measure sound levels, used in industrial machinery, noise pollution monitoring, and security systems
• Accelerometer sensors: measure acceleration rate, tilt, and vibration, used in vehicle safety features, mobile phones, and more
• Flow sensors: measure rate of gas, liquid, or powder flow, used in water systems and pipes
• Gas sensors: detect presence of gases, used in confined spaces, gas leak detection, and more
• Humidity sensors: measure levels of water vapour, used in greenhouses and monitoring moisture
• Infra-red sensors: detect motion or heat sources, used in security systems and emergency services
• Level sensors: measure liquid levels, used in petrol tanks, water tanks, and leak detection
• Light sensors: measure light levels, used in automatic light switching, street lights, and headlights
• Magnetic field sensors: detect presence and strength of magnetic fields, used in anti-lock braking systems and monitoring rotating machinery
• Moisture sensors: detect presence and levels of moisture, used in soil monitoring, building damp monitoring, and more
• pH sensors: measure acidity or alkalinity, used in soil monitoring, chemical processes, and more
• Pressure sensors: measure gas, liquid, or physical pressure, used in tyre pressure monitoring, manufacturing processes, and more
• Proximity sensors: measure distance, used in robotics, safety systems, and more
• Temperature sensors: measure temperature, used in swimming pools, chemical processes, and more

Primary Storage

• Primary storage is directly accessible by the CPU
• Includes RAM, Cache, and ROM
• Purpose of RAM: to store data, instructions, and software currently in use
• Characteristics of RAM:
  • RAM is also called main memory
  • Faster read/write speeds than secondary storage
  • Volatile, meaning data is lost when the computer is switched off
  • Can be increased in size to improve operational speed
• Types of RAM technology:
  • Dynamic RAM (DRAM)
  • Static RAM (SRAM)
  • DRAM: uses transistors and capacitors, needs to be constantly refreshed, less expensive to manufacture
  • SRAM: uses flip flops, doesn't need to be constantly refreshed, faster data access time, more expensive to manufacture

Cache Memory

• Purpose: store frequently/recently used instructions and data
• Characteristics:
  • Faster read/write speeds than RAM
  • Volatile, meaning data is lost when the computer is switched off
  • Increasing cache size can improve performance

ROM Memory

• The role of ROM is to store the computer's boot-up sequence
• Characteristics:
  • Non-volatile, meaning data is stored even when the computer is switched off
  • Read-only, meaning data cannot be written to ROM
  • Data cannot be altered
  • Always used to store BIOS and other data needed at start-up

Secondary Storage

• Not directly accessed by the CPU
• Used for permanent storage of data
• Non-volatile, meaning data is stored even when the computer is switched off
• Characteristics:
  • Slower data access speeds than primary storage
  • Larger capacity
  • Software such as the operating system is saved permanently

Types of Secondary Storage

• Magnetic storage
• Solid State storage
• Optical storage

Virtual Memory

• Part of secondary storage that acts as RAM when RAM is full
• Prevents computer system crashes when RAM is full
• Data is switched between virtual memory and RAM by the operating system

Cloud Storage

• A method of data storage where data is stored on remote servers
• Benefits:
  • Almost unlimited storage capacity
  • Recovery of data in case of failure
  • Remote backup of data
  • No need for external storage devices
  • Files can be accessed from anywhere
• Drawbacks:
  • Risk of loss of data if the cloud storage company fails
  • High costs for large storage capacity
  • Slow internet connections can cause problems

Network Hardware

• Network Interface Card (NIC)
• Wireless Network Interface Card (WNIC)
• Media Access Control (MAC)
• Internet Protocol (IP)

Media Access Control (MAC)

• A hardware identification number that uniquely identifies each device on a network
• Manufactured into every Network Interface Controller (NIC)
• Cannot be changed
• 12-digit hexadecimal number

Internet Protocol (IP)

• Used to identify a device on the Internet or network
• Allocated by the network or Internet Service Provider (ISP)
• Can be used in place of URL
• IP addresses can be IPv4 or IPv6
• IP addresses can be static or dynamic

Advantages of IPv6

• Removes the risk of IP address collisions
• Has built-in authentication checks
• Allows for more efficient packet routes

Routers

• Enable data packets to be routed between different networks
• Take data transmitted in one format and convert it to a protocol and format understood by another network
• Allow different networks to communicate