CPU Architecture and Components

• CPUs process and execute instructions and data to produce an output.
• Microprocessors are integrated circuits on a single chip that perform fewer functions than a regular CPU.

CPU Components: Units

• Arithmetic Logic Unit (ALU) handles arithmetic operations (addition, subtraction, etc.) and logical operations ("AND", "OR", "NOT" etc.).
• Control Unit (CU) manages and synchronizes data and instruction transfers within the CPU by sending control signals and decoding instructions.

CPU Components: Registers

• Registers are high-speed memory components within the CPU that temporarily store important information.
• Program Counter (PC) stores the memory address of the next instruction to be processed.
• Memory Address Register (MAR) stores the memory address of the instruction/data to be fetched from RAM.
• Memory Data Register (MDR) stores data or instructions fetched from RAM.
• Current Instruction Register (CIR) stores the instruction being processed or decoded by the CPU.
• Accumulator (ACC) stores interim or final values from ALU operations.

CPU Components: Buses

• Buses are communication systems that transfer data and instructions between components.
• Address bus carries the memory address of data/instructions.
• Data bus carries the actual data/instructions.
• Control bus carries control signals to and from the CU.

Fetch Stage

• Instructions or data is retrieved from memory and brought to the CPU.
• The Program Counter's address is copied to the Memory Address Register via the address bus.
• The Memory Address Register sends the address to RAM via the address bus.
• RAM locates the data/instruction using the address and copies it to the Memory Data Register via the data bus.
• The Memory Data Register transfers the data/instruction to the Current Instruction Register via the data bus.
• The Program Counter is incremented to hold the next instruction's address.

Decode Stage

• The Control Unit decodes instructions using an instruction set written in low-level machine code.
• Instruction sets are sequences of instructions that the CPU understands to carry out certain operations.

Execute Stage

• Arithmetic and Logical Unit (ALU) carries out arithmetic or logical operations.
• The Accumulator is used to store any values created during execution by the ALU.
• The command is executed after all calculations.
• The whole process is repeated for each instruction or piece of data.

Cache

• Cache is internal temporary storage inside the CPU for frequently used data and instructions.
• Using cache reduces the need to fetch from RAM, which speeds up processing.
• Larger cache size typically improves CPU performance.
• Excessively large cache can cause delays during information fetching due to prolonged searching.

Clock

• The System Clock controls processing speed, execution time, and synchronization of the FDE cycle.
• Clock speed is measured in Hertz (Hz), with an average computer clock speed around 2 GHz (2 billion instructions per second).
• Higher clock speed processes more instructions per second, enhancing performance.
• Overclocking can cause overheating.

Cores

• Cores execute the FDE cycle, with each core processing one instruction at a time.
• Multicore processors can process multiple instructions simultaneously, improving multitasking and overall performance.

Embedded Systems

• Embedded systems are combinations of software and hardware built into a device, running on firmware to perform a specific, dedicated function.
• Embedded systems contrast with general-purpose computers due to their singular purpose, being designed for specific tasks.
• Used in appliances, cars, security, lighting and vending machines.
• Advantages: small size, low cost, remote controllability, minimal power consumption, and no OS dependence.
• Disadvantages: Difficult to update, hacking susceptibility, specialized repair needs, environmental disposal concerns, and potentially confusing interface.

Input Devices

• Input devices enter data into a system.

Barcode Scanner

• Uses laser light to read parallel dark and light lines.
• Line width represents a binary code.
• Used for automatic stock control.
• A red LED or laser reads the barcode.
• Reflected light from dark areas is read by sensors.
• A pattern is generated and converted to digital form.

Digital Camera

• Scanned with an app on a mobile device.
• Captures images.
• Alignment is defined by three large squares.
• Black squares = less light reflection, white squares = more light reflection.
• Each small square/pixel converts to a binary value.

Keyboard

• Used for interacting with computers via keystrokes.
• Used in business and personal contexts (e.g., entering quantities, gaming).
• Connected via USB or wireless link.
• Each key has an ASCII value.
• Keystrokes are translated into digital signals.
• Can cause Repetitive Strain Injury (RSI).
• Ergonomic keyboards are used to address these issues, with a different key arrangement for comfort.

Microphone

• Converts audio signals into electrical signals, which are digitized by a sound card.
• Connects via USB or wireless.
• Voice recognition and speech recognition are applications.
• Translated words create wave patterns, which are compared to saved patterns.
• Used in security systems, like unlocking phones.

Optical Mouse

• Pointing device, typically connects via USB or wireless.
• Traditional mice used a moving ball to detect pointer position.
• Modern mice use a red laser to track position.
• An LED shines light on the surface.
• A light-detector chip measures reflected light.
• This converts analog hand movements into digital X and Y coordinates.
• Scroll wheel rotations detected and converted to digital signals using potentiometers.

Trackerball

• Commonly used in industrial environments, such as control rooms.
• Doesn't require movement, saving desk space.
• Operator is less likely to experience injuries, like RSI.
• A ball is used to control the cursor.
• Buttons are used to select icons and functions.

QR Code Scanner

• Scanned using app on mobile device
• The camera is used to scan/capture the image
• The three large squares are used to define the alignment
• Black squares reflect less light/white squares reflect more light
• The app/device processes the image
• Each small square/pixel is converted to a binary value
• Eliminates manual website address entry.
• Store URLs found in magazines, buses, trains, or business cards.

Touch Screen

• These input devices come in various forms
• Resistive touchscreens use layers of material that transmit electric currents when pressed.
• Coordinate changes based on the point of contact.
• They are inexpensive, and use styluses, fingers, gloved fingers, or pens.
• These have poor sunlight visibility, can be scratched, wear over time, and do not allow multi-touch.
• Capacitive touchscreens use a conductive layer to create an electrostatic field.
• Sensors monitor the electrostatic field.
• Charge transfers to finger on contact, calculating coordinates.
• Insulators block current/charge, affecting the electrostatic field.
• They are durable, offer good sunlight visibility, and multi-touch functionality.
• Capacitive touchscreens can break, and cannot be used with gloves.
• Infrared touchscreens use an invisible grid of infrared beams.
• Sensors detect touch when infrared beams are broken.
• Positions are calculated using this information.
• They are durable, offer multi-touch, and work with styluses or gloves.
• These are expensive, fragile, and sensitive to dust.

2D Scanner

• 2D scanners illuminate a document, capture the reflected light using mirrors and lenses, convert to a digital file and produces a 2D digital image.
• They're used to scan passports at airports.

3D Scanners

• 3D scanners shine a laser over an object's surface.
• They record measurements and convert them into a digital file to produce a 3D digital model.
• They're used to create 3D images in CT scans.

Output Devices

• Output devices transmit information to the user.

Actuator

• Actuators use motors, relays, valves or robot arms to operate machines automatically.
• Requires a Digital to Analogue (DAC) converter.
• Used in autonomous cars, climate control, or security.

Digital Light Processing (DLP) Projector

• Uses white light and micro mirrors on a chip to project images.
• Number of micro mirrors determines resolution.
• Light separates into RGB colors, for about 16 million combinations.
• Micro mirrors tilt towards or away from the light source to produce colors.

Inkjet Printer

• Sprays ink droplets onto paper using a print head with nozzles.
• Uses individual ink cartridges for each color.
• A stepper motor moves the print head.
• It uses thermal bubble and piezoelectric technology.
• Characters are formed from small ink droplets, propelled on by crystal movement.
• Used for photographs.

Laser Printer

• The printer driver formats data for the printer.
• The data sends to the printers and is stored in its buffer.
• Printing drum gets a positive charge.
• Laser scans the drum, removing the positive charge from certain areas.
• Negatively charged ares attract positively charged toner.
• Paper is rolled over the drum.
• Toner transfers to the paper.
• Paper passes through a fuser to melt and fix the toner.

Light Emitting Diode (LED) Screen

• Flat panel display that uses light-emitting diodes as pixels to backlight the LCD panel eliminating the need for CCFL.

Liquid Crystal Display (LCD) Screen

• A flat panel display that modulates light using liquid crystals and diodes.
• Diodes form pixels, grouped in red, blue, green (RGB).
• Modern LCDs use LEDs for backlighting, replacing CCFL.
• CCFL used two florescent tubes for providing light to the screen.
• LCDs require backlighting tech, since they do not emit light.

Liquid Crystal Display (LCD) Projector

• Light is propelled through this projector from the LED.
• Light waves are reflected by mirrors into RGB colors.
• Then passed through 3 LCD screens
• Images were then combined through a prism to produce a full color image.
• The resulting colored image is projected onto the screen.

Speaker

• Sound from a computer passes through a Digital to Analogue Converter (DAC).
• And through an amplifier.
• Audio outputs for listening to audios or videos.

Headphones

• Headphones provide instructions to users with disabilities or read text.
• Digital sound signals pass through a DAC, then an amplifier.
• The sound outputs through its speakers.

3D Printer

• 3D printers construct solid objects by layering powdered resin, metal, paper, or ceramic.

Sensors

• Input devices that record data from their environment at set intervals to monitor different conditions.
• Acoustic sensors record sound levels for use in security systems.
• Accelerometers record acceleration forces for earthquake warnings.
• Flow sensors track liquid/gas/steam flow in pipes/plumbing.
• Gas sensors measure gas concentration in carbon monoxide detectors.
• Humidity sensors measure humidity levels.
• Infrared sensors identify rays in security systems.
• Level sensors measure liquid/gas volume.
• Light sensors measure light levels for automatic lighting.
• Magnetic field sensors detect magnetic fields.
• Moisture sensors detect moisture.
• pH sensors measure water/soil pH levels.
• Pressure sensors measure pressure for intrusion detection.
• Proximity sensors measure object distance for automatic doors/robots.
• Temperature sensors measure temperature for cooling systems.

Data Storage: Primary

• Primary storage is directly accessible by the CPU.
• RAM and ROM are examples of primary storage.

Data Storage: Secondary

• Secondary storage isn't directly accessible by the CPU and isn't currently required – typically hard-disk drives for files, and USB drives etc for external storage.
• It's non-volatile, meaning that data persists when power is off.
• It stores data for transfer.
• Pen drives and CDs are secondary storage devices.

Primary Storage: RAM

• RAM temporarily stores data and instructions actively in use by the CPU.
• For example, for currently open application program files.
• RAM is volatile.

Primary Storage: ROM

• ROM permanently stores data required to initially boot the computer, such as the BIOS.
• ROM is non-volatile.
• RAM compared to ROM: RAM is temporary and volatile, storing data in CPU use which constantly changes, and is easy to increase in size, whereas ROM is permanent and non-volatile, storing programs to boot the computer which stays fixed, and is difficult to resize.

Secondary Storage: Magnetic Storage

• It uses magnetised and demagnetised dots to store data on spinning platters with read/write heads.
• Platters have tracks and sectors.
• "1" is represented by a magnetised dot, and "0" by demagnetised dot.
• Hard disk drives are an example.

Secondary Storage: Optical Storage

• Optical storage uses lasers to store data by creating pits and lands on circular discs.
• A laser beam burns the data onto the disc and a laser reads the data of.
• Pits represent "1" and lands represent "0".
• Data is written in a spiral or circular pattern.
• CDs, DVDs, and Blu-Rays are optical storage examples.

Secondary Storage: Solid-State Storage

• Solid-state storage uses transistors and cells to store data on a semiconductor chip.
• Transistors form a grid which contain a control gate over a floting gate.
• Transistors control electron flow to a floating gate.
• Storing electrons changes the transistor's binary value.
• Solid state devices use NAND or NOR structure
• Pen-drives and SSDs are solid state storage devices.

Virtual Memory

• Virtual memory extends the RAM by using a portion of the hard disk drive.
• Data in RAM is split into pages which are not in immediate use, being moved to virtual memory to free up space.
• New data enters from secondary storage.
• Finally, data not needed in RAM transfers back to secondary storage and pages initially in virtual memory are reloaded.

Cloud Storage

• Remote data storage is maintained by a third party is known as cloud storage.
• Cloud Storage vs. Local Storage:
• Cloud storage can be accessed everywhere, with internet, requires no hardware costs, makes backing up data easier, offers easy storage size adjustments and allows trusting third parties with person data.
• Local storage allows access with storage, it requires no internet, requires hardware costs, backup issues will need to be resolved in-house, the storage size can prove difficult to adjust, removes trust issues and privacy concerns since it removes sharing data with third-parties.

Network Interface Card (NIC)

• A NIC connects computers to networks, linking to routers, and includes the MAC address.

Media Access Control (MAC) Address

• A MAC address uniquely identifies each computer in a network.
• It is located on the NIC on the computer.
• Its written in hexadecimal format.
• Manufacturer's code = first six digits, device's serial no = last six digits.
• 48 bits in total; 24 bits manufacturer's code, 24 bits device's serial no.

Internet Protocol (IP) Address

• The network assigns an IP address, which uniquely identifies each computer on a network
• Static IP never changes unless requested, allows devices to be traceable and therefore it's comparatively unsafe.
• Dynamic IP changes when a computer connects, which makes the IP harder to trace and has better privacy.

IP Address Structure

• IPv4 is written in denary digits separated by dots, contains 4 groups (32 bits) of numbers between 0-255 (e.g. 24.2.89.232), has fewer available unique addresses
• IPv6 is hexadecimal separated by colons, contains 8 groups (128 bits) of numbers between 0000-FFFF (e.g. 1234:0A34:1F20:0000:FFFF:998B:900C:5ABC) and has more available addresses