3.1 Computers and Their Components

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Need for Input, Output, Primary Memory and Secondary Storage

Input Devices

Purpose: Allow data and instructions to be entered into a computer system.

Why needed:

• Enable user interaction with the computer
• Convert real-world data into digital form
• Provide means to control computer operations
• Capture data from the environment (sensors)

Examples: Keyboard, mouse, microphone, scanner, sensors, touchscreen

Output Devices

Purpose: Present data from the computer in a human-readable form or control external devices.

Why needed:

• Provide feedback to users
• Display results of processing
• Create permanent records (printouts)
• Control other devices (actuators)

Examples: Monitor, printer, speakers, actuators, VR headset

Primary Memory

Purpose: Temporarily stores data and instructions currently being used by the CPU.

Why needed:

• Much faster than secondary storage
• CPU can only access data in primary memory
• Holds running programs and their data
• Essential for the stored program concept

Types: RAM (Random Access Memory), ROM (Read Only Memory), Cache

Secondary Storage

Purpose: Permanently stores data, programs, and the operating system when not in use.

Why needed:

• Non-volatile (retains data when power off)
• Much larger capacity than primary memory
• Cheaper per byte than primary memory
• Portable storage for data transfer

Types: Magnetic (hard disk), Optical (CD/DVD/Blu-ray), Solid State (SSD, USB flash drive)

Component	Volatility	Speed	Capacity	Purpose
Primary Memory	Volatile (RAM)	Very Fast	Small	Active programs/data
Secondary Storage	Non-volatile	Slower	Large	Long-term storage
Cache	Volatile	Fastest	Tiny	Frequently used data
ROM	Non-volatile	Fast	Small	Boot instructions

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Embedded Systems

Definition: A dedicated computer system designed to perform one or a few dedicated functions, often as part of a larger device.

Characteristics

• Designed for specific tasks
• Contains both hardware and software
• Typically has real-time computing constraints
• Limited user interface (or none)
• Low power consumption
• Low cost per unit
• Highly reliable and stable

Examples

• Consumer devices: Microwave ovens, washing machines, digital watches, smart TVs
• Automotive: Engine control units, ABS brakes, cruise control
• Medical: Pacemakers, insulin pumps, patient monitors
• Industrial: Robot controllers, assembly line monitors
• Networking: Routers, switches, firewalls

Benefits of Embedded Systems

• Dedicated function: Optimised for specific task
• Low cost: Mass production reduces unit cost
• Low power: Can run on batteries for long periods
• Small size: Can fit in compact devices
• Reliability: Fewer components to fail
• Real-time performance: Can respond instantly to events
• No user intervention: Operate autonomously

Drawbacks of Embedded Systems

• Limited functionality: Cannot be reprogrammed for other tasks
• Difficult to upgrade: Hardware often fixed
• Hard to fix: May require replacing entire device
• Security risks: Can be hacked if connected to networks
• Obsolescence: Whole device replaced when system outdated
• Debugging challenges: Hard to diagnose problems

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Hardware Devices: Principal Operations

Laser Printer

Operation process:

1. Processing: Printer receives data from computer; builds page image in memory
2. Charging: Primary corona wire applies negative charge to photosensitive drum
3. Writing: Laser beam discharges specific areas on drum, creating latent image
4. Developing: Toner (oppositely charged) attracted to discharged areas
5. Transferring: Paper given positive charge; toner transfers to paper
6. Fusing: Heat and pressure rollers melt toner onto paper
7. Cleaning: Excess toner removed from drum; drum discharged

Key components: Photosensitive drum, laser scanning unit, toner cartridge, fuser unit, corona wires

3D Printer

Operation process:

1. Design: 3D model created in CAD software or scanned
2. Slicing: Software divides model into thin horizontal layers
3. Printing: Material deposited layer by layer
4. Solidification: Material hardens (cooling, UV light, or chemical reaction)
5. Post-processing: Support removal, sanding, curing

Common technologies:

• FDM (Fused Deposition Modeling): Melts and extrudes plastic filament
• SLA (Stereolithography): UV laser cures liquid resin
• SLS (Selective Laser Sintering): Laser fuses powder material

Microphone

Operation process:

1. Sound waves: Air pressure variations hit microphone
2. Transduction: Sound waves converted to electrical signals
3. Types:

• Dynamic: Moving coil in magnetic field generates current
• Condenser: Diaphragm movement changes capacitance
• Piezoelectric: Crystal deformation generates voltage

1. Amplification: Weak signal boosted
2. ADC: Analogue signal converted to digital (for computer input)

Speakers

Operation process:

1. Signal input: Electrical audio signal received
2. Amplification: Signal boosted (if passive speakers)
3. Electromagnet: Varying current creates varying magnetic field
4. Voice coil: Coil moves back and forth in magnetic field
5. Diaphragm: Attached cone moves air, creating sound waves
6. Enclosure: Prevents sound wave cancellation

Magnetic Hard Disk (HDD)

Operation process:

1. Platters: Multiple disks coated with magnetic material spin at high speed (5400-15,000 RPM)
2. Read/Write heads: Float nanometers above platters on air bearing
3. Actuator arm: Moves heads across platters
4. Writing: Electromagnet in head magnetises tiny regions (domains)

• Direction of magnetisation = 0 or 1

1. Reading: Head detects magnetic orientation as it passes over
2. Controller: Manages data transfer, caching, error correction

Key characteristics:

• Mechanical parts → slower, less durable, but cheaper per GB
• Sequential access faster than random access
• Susceptible to shock and magnetism

Solid State Memory (Flash)

Operation process:

1. Floating gate transistors: Store charge to represent data
2. Writing: High voltage forces electrons through insulation into floating gate
3. Reading: Threshold voltage checked to determine if gate charged
4. Erasing: Voltage applied to remove electrons from floating gate
5. Controller: Manages wear leveling, error correction, garbage collection

Key characteristics:

• No moving parts → faster, more durable, quieter
• Limited write cycles (wear out over time)
• Faster read than write
• More expensive per GB than HDD

Optical Disc Reader/Writer (CD/DVD/Blu-ray)

Operation process – Reading:

1. Disc rotates: Constant linear velocity or constant angular velocity
2. Laser: Shines beam onto disc surface
3. Reflection: Lands (flat) reflect; pits (indentations) scatter light
4. Photodiode: Detects reflected light intensity
5. Decoding: Pattern of reflections converted to binary data

Operation process – Writing:

• CD-R/DVD-R: Laser heats dye layer, changing reflectivity permanently
• CD-RW/DVD-RW: Laser changes phase of recording layer (crystalline ↔ amorphous)
• Blu-ray: Shorter wavelength blue-violet laser (405nm) allows higher density

Disc types:

Type	Capacity	Laser wavelength	Use
CD	700 MB	780 nm (infrared)	Audio, software
DVD	4.7 GB (single layer)	650 nm (red)	Movies, data
Blu-ray	25 GB (single layer)	405 nm (violet)	HD video, games

Touchscreen

Types and operation:

Resistive touchscreen:

1. Two flexible layers with gap between
2. Pressure pushes layers together
3. Electrical contact detected at point of touch
4. Controller calculates position

• Benefits: Works with finger, stylus, glove; low cost
• Drawbacks: Lower clarity; pressure needed

Capacitive touchscreen:

1. Glass coated with transparent conductor (ITO)
2. Body’s capacitance affects electrostatic field
3. Sensors at corners measure capacitance change
4. Controller triangulates position

• Benefits: High clarity; multi-touch; durable
• Drawbacks: Only works with conductive stylus/finger; expensive

Infrared touchscreen:

1. LEDs and photodetectors create grid of IR beams
2. Touch interrupts beams
3. Controller identifies interrupted beams

• Benefits: Works with any object; high durability
• Drawbacks: Can be affected by sunlight; bulky

Virtual Reality Headset

Operation process:

1. Tracking: Sensors track head position and orientation

• Accelerometers, gyroscopes, magnetometers
• External cameras/lighthouse (outside-in tracking)
• Inside-out tracking (cameras on headset)

1. Rendering: Computer generates two slightly different images (stereoscopic)
2. Display: High-resolution screens show images at high refresh rate (90-120Hz)
3. Optics: Lenses focus and distort images to create 3D effect
4. Audio: Spatial audio creates immersive sound
5. Latency compensation: Predict movement to reduce motion sickness

Key components: Display panels, lenses, tracking sensors, audio system, processing unit

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Use of Buffers

Definition: A temporary storage area in memory used to compensate for speed differences between two devices or processes.

Why Buffers are Needed

• Speed matching: Fast device can continue working while slow device catches up
• Data bursts: Handle bursts of data without losing information
• Streaming: Smooth out variations in data flow
• I/O operations: Allow CPU to continue processing while I/O occurs

How Buffers Work

Example: Printing a document

1. Application sends data to printer buffer at high speed
2. Buffer stores data temporarily
3. Printer reads from buffer at its own slower speed
4. Application can continue other work immediately
5. If buffer fills, application must wait or pause

Example: Video streaming

1. Video data arrives over network (variable speed)
2. Buffer stores several seconds of video
3. Video player reads from buffer at constant rate
4. If network slows temporarily, playback continues from buffer

Types of Buffers

• Input buffer: Holds data arriving from input device
• Output buffer: Holds data waiting to be sent to output device
• Circular buffer: Fixed-size buffer that wraps around
• Double buffering: Two buffers alternate (one fills while other empties)

Benefits

• Efficiency: CPU not tied to slow I/O devices
• Smooth operation: Prevents gaps in data flow
• Error handling: Can retry failed transfers
• Multitasking: Multiple processes can share resources

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RAM vs ROM

Random Access Memory (RAM)

Characteristics:

• Volatile: Loses data when power off
• Read/Write: Can read and write data
• Fast access: Direct access to any location
• Temporary storage: Holds running programs and data
• Larger capacity: Typically GB to TB

Purpose:

• Store operating system while computer is running
• Hold currently executing programs
• Store data being processed
• Provide working space for applications

Use in devices:

• PCs/Tablets/Phones: Main system memory
• Printers: Store pages being printed
• Routers: Buffer packets and routing tables
• Graphics cards: Video RAM (VRAM) for frame buffer

Read Only Memory (ROM)

Characteristics:

• Non-volatile: Retains data when power off
• Read mostly: Difficult or impossible to write (varies by type)
• Permanent storage: Contains fixed data
• Smaller capacity: Typically KB to MB
• Slower than RAM (generally)

Purpose:

• Store bootloader/firmware (BIOS/UEFI)
• Hold bootstrap program that starts computer
• Contain fixed instructions for embedded systems
• Store critical system data

Use in devices:

• PCs: BIOS/UEFI firmware
• Embedded systems: Complete program storage (microwave, washing machine)
• Calculators: Operating system
• Game consoles: Cartridge games
• Car ECUs: Engine control programs

Feature	RAM	ROM
Volatility	Volatile (data lost)	Non-volatile (data retained)
Read/Write	Read and write	Primarily read
Speed	Fast	Slower (generally)
Capacity	Large (GB/TB)	Small (KB/MB)
Content	Temporary data/programs	Permanent firmware
Modification	Easy	Difficult or impossible
Use	Working memory	Boot code, firmware

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SRAM vs DRAM

Dynamic RAM (DRAM)

Characteristics:

• Uses capacitor and transistor per cell
• Capacitor stores charge (1) or no charge (0)
• Needs constant refreshing (capacitors leak charge)
• Simple design → high density, low cost
• Slower access time (50-70ns)
• Lower power consumption when idle

Operation:

1. Write: Charge or discharge capacitor
2. Read: Sense amplifier detects charge level
3. Refresh: Must read and rewrite every few milliseconds

Use in devices:

• Main system memory (RAM sticks)
• Graphics card memory (GDDR)
• Where large capacity needed at reasonable cost

Static RAM (SRAM)

Characteristics:

• Uses flip-flop circuit (6 transistors per cell)
• No refresh needed (holds state as long as powered)
• Complex design → lower density, higher cost
• Much faster access time (10-20ns)
• Higher power consumption
• No refresh overhead

Operation:

1. Write: Set flip-flop state
2. Read: Sense flip-flop state directly
3. No refresh needed

Use in devices:

• CPU cache: L1, L2, L3 cache
• Registers: Inside CPU
• Buffers: Network switches, routers
• Where speed is critical and capacity moderate

Comparison

Feature	SRAM	DRAM
Cell structure	6 transistors	1 transistor + capacitor
Speed	Very fast (10-20ns)	Fast (50-70ns)
Density	Low	High
Cost per bit	High	Low
Power consumption	Higher (active)	Lower (but needs refresh)
Refresh needed	No	Yes (every ~64ms)
Use	Cache, registers	Main memory

Why Choose SRAM or DRAM

Choose SRAM when:

• Speed is critical (CPU cache)
• Small size acceptable
• Power for active operation available
• Cost less important

Choose DRAM when:

• Large capacity needed
• Cost is important
• Slightly slower speed acceptable
• Main system memory

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Programmable ROM Types

PROM (Programmable Read Only Memory)

Characteristics:

• Blank when manufactured
• Programmed once by user (one-time programmable)
• Programming: High voltage blows fuses or charges floating gates
• Cannot be erased or reprogrammed

Process:

1. Purchase blank PROM
2. Use PROM programmer device
3. Apply high voltage to selected address lines
4. Fuses blow (or charge traps) permanently
5. Data cannot be changed

Use:

• Small production runs
• Prototyping
• When data absolutely must not change
• Legacy systems

EPROM (Erasable Programmable ROM)

Characteristics:

• Can be erased and reprogrammed multiple times
• Erasure: Expose to strong ultraviolet (UV) light
• Window on package allows UV to reach chip
• Programming: Similar to PROM but reversible
• Erases entire chip (not selective)

Process:

1. Program using EPROM programmer
2. To erase: Place under UV lamp for 20-30 minutes
3. UV light discharges floating gates
4. Can then reprogram
5. Requires removal from circuit

Use:

• Development and testing
• Firmware that may need updates
• Boot ROMs in older systems
• Where UV erasure practical

EEPROM (Electrically Erasable PROM)

Characteristics:

• Can be erased and reprogrammed electrically
• No UV light needed; can be programmed in-circuit
• Can erase individual bytes (not whole chip)
• Slower to write than read
• Limited write cycles (typically 100,000 – 1,000,000)

Process:

1. Apply specific voltages to control pins
2. Electrical charge removes from floating gate
3. Can write new data
4. Can be done without removing from circuit

Modern variants:

• Flash memory: Type of EEPROM with block erasure
• Faster and higher density than traditional EEPROM
• Used in USB drives, SSDs, memory cards

Comparison

Feature	PROM	EPROM	EEPROM
Programmability	Once	Multiple	Multiple
Erasure method	Not erasable	UV light	Electrical
Erasure scope	N/A	Entire chip	Byte-by-byte
In-circuit programming	No	No	Yes
Write cycles	1	1,000+	100,000+
Cost	Low	Medium	Higher
Use	Permanent data	Development	Firmware updates

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Monitoring and Control Systems

Monitoring vs Control

Monitoring:

• System measures and records data
• No automatic action taken
• Human may act on information
• Examples: Weather station, security camera, patient monitor

Control:

• System measures data AND takes automatic action
• Uses feedback to maintain desired state
• Examples: Thermostat, cruise control, industrial robot

Aspect	Monitoring	Control
Input	Sensors measure	Sensors measure
Processing	Compare to thresholds	Calculate required action
Output	Display/alert	Actuators make changes
Human role	Interprets and acts	May be none (automatic)
Example	Temperature displayed	Temperature adjusted

Sensors

Definition: Devices that detect and respond to physical input from the environment.

Common sensor types:

Temperature sensor:

• Measures heat energy
• Types: Thermocouple, thermistor, RTD
• Applications: Thermostats, weather stations, industrial processes

Pressure sensor:

• Measures force per unit area
• Types: Piezoresistive, capacitive
• Applications: Altimeters, weather monitoring, hydraulic systems

Infrared sensor:

• Detects infrared radiation (heat)
• Passive: Detects emitted IR (motion sensors)
• Active: Emits and detects IR (proximity)
• Applications: Night vision, remote controls, motion detection

Sound sensor:

• Detects sound waves
• Microphone, ultrasonic sensor
• Applications: Security systems, acoustic monitoring, ultrasound

Light sensor:

• Detects visible light intensity
• Photodiode, LDR (light dependent resistor)
• Applications: Automatic lighting, camera exposure

Other sensors:

• Humidity sensor, gas sensor, accelerometer, proximity, magnetic field

Actuators

Definition: Devices that convert electrical signals into physical action.

Types:

Electric motor:

• Converts electricity to rotational motion
• Types: DC motor, stepper motor, servo motor
• Applications: Fans, robots, disk drives, conveyor belts

Solenoid:

• Electromagnet that moves a plunger
• Linear motion (push/pull)
• Applications: Door locks, valves, relays

Hydraulic actuator:

• Uses pressurised fluid
• Very high force
• Applications: Heavy machinery, aircraft controls

Pneumatic actuator:

• Uses compressed air
• Fast, clean operation
• Applications: Factory automation, brakes

Heater/Cooler:

• Changes temperature
• Peltier device, heating element
• Applications: HVAC systems, ovens, refrigerators

Feedback

Definition: Process where part of output signal is returned to input to maintain desired state.

Importance of feedback:

• Maintains stability
• Compensates for disturbances
• Achieves precise control
• Reduces errors

Negative feedback:

• Output opposes changes
• Maintains set point
• Example: Thermostat (too hot → turn off heat)
• Most common in control systems

Positive feedback:

• Output amplifies changes
• Leads to runaway condition
• Example: Microphone feedback (squeal)
• Used in oscillators, some specialised systems

Feedback Loop Example: Thermostat

Set temperature: 21°C
        ↓
[Controller] ←──────┐
        ↓            │
[Heater]             │ (feedback)
        ↓            │
[Room temperature]───┘
        ↓
[Sensor measures 22°C]
        ↓
[Controller compares: 22°C > 21°C]
        ↓
[Controller turns heater OFF]
        ↓
[Temperature drops to 21°C]
        ↓
[Controller turns heater ON]

Monitoring System Example: Weather Station

1. Sensors measure:

• Temperature (thermometer)
• Pressure (barometer)
• Humidity (hygrometer)
• Wind speed (anemometer)

1. Data logged to database
2. Processing: Calculate trends, averages
3. Output: Display on screen, website
4. No automatic control: Human interprets and acts

Control System Example: Greenhouse Automation

1. Sensors monitor:

• Temperature, humidity, light, soil moisture

1. Controller compares to desired ranges:

• Too hot → open vents, turn on fans
• Too dry → turn on irrigation
• Too dark → turn on grow lights

1. Actuators respond:

• Motor opens vents
• Pump starts irrigation
• Relays turn on lights

1. Continuous monitoring maintains optimal conditions

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3.2 Logic Gates and Logic Circuits

Logic Gate Symbols and Functions

Basic Logic Gates

NOT Gate (Inverter)

• Function: Output is opposite of input
• Symbol: Triangle with small circle
• Boolean expression: Q = NOT A or Q = Ā

A	Q
0	1
1	0

AND Gate

• Function: Output is 1 ONLY when ALL inputs are 1
• Symbol: D-shaped
• Boolean expression: Q = A AND B or Q = A·B

A	B	Q
0	0	0
0	1	0
1	0	0
1	1	1

OR Gate

• Function: Output is 1 when ANY input is 1
• Symbol: Curved shield shape
• Boolean expression: Q = A OR B or Q = A+B

A	B	Q
0	0	0
0	1	1
1	0	1
1	1	1

Universal Gates

NAND Gate (NOT AND)

• Function: AND followed by NOT
• Output is 0 ONLY when ALL inputs are 1
• Symbol: AND with circle
• Boolean expression: Q = NOT (A AND B) or Q = A·B

A	B	Q
0	0	1
0	1	1
1	0	1
1	1	0

NOR Gate (NOT OR)

• Function: OR followed by NOT
• Output is 1 ONLY when ALL inputs are 0
• Symbol: OR with circle
• Boolean expression: Q = NOT (A OR B) or Q = A+B

A	B	Q
0	0	1
0	1	0
1	0	0
1	1	0

Exclusive Gate

XOR Gate (Exclusive OR)

• Function: Output is 1 when inputs are DIFFERENT
• Symbol: OR with extra line
• Boolean expression: Q = A XOR B or Q = A⊕B

A	B	Q
0	0	0
0	1	1
1	0	1
1	1	0

Gate Summary

Gate	Function	Output = 1 when…	Expression
NOT	Invert	Input = 0	Q = NOT A
AND	All	All inputs = 1	Q = A·B
OR	Any	Any input = 1	Q = A+B
NAND	Not all	Not all inputs = 1	Q = A·B
NOR	Not any	No inputs = 1	Q = A+B
XOR	Different	Inputs different	Q = A⊕B

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Constructing Logic Circuits

From a Problem Statement

Example Problem:
A security system should activate an alarm (output X) if:

• The motion sensor (A) is triggered AND it’s after dark, OR
• The door sensor (B) is opened AND the system is armed (C)

Step 1: Identify inputs and output

• Inputs: A (motion), D (dark sensor), B (door), C (armed)
• Output: X (alarm)

Step 2: Write Boolean expression

• Part 1: Motion AND dark = A·D
• Part 2: Door AND armed = B·C
• Combined: X = (A·D) + (B·C)

Step 3: Draw circuit

A ──┬──[AND]──┐
D ──┘         │
           [OR]── X
B ──┬──[AND]──┘
C ──┘

From a Logic Expression

Example: X = (A·B) + (NOT C)

Step 1: Identify operations order

• First: AND (A and B)
• Second: NOT (C)
• Third: OR (results of AND and NOT)

Step 2: Draw gates in order

A ──┬──[AND]──┐
B ──┘         │
           [OR]── X
C ──[NOT]─────┘

From a Truth Table

Example Truth Table:

A	B	C	X
0	0	0	0
0	0	1	1
0	1	0	0
0	1	1	1
1	0	0	1
1	0	1	0
1	1	0	1
1	1	1	1

Step 1: Identify rows where output = 1

• Row 2: A=0, B=0, C=1 → NOT A AND NOT B AND C
• Row 4: A=0, B=1, C=1 → NOT A AND B AND C
• Row 5: A=1, B=0, C=0 → A AND NOT B AND NOT C
• Row 7: A=1, B=1, C=0 → A AND B AND NOT C
• Row 8: A=1, B=1, C=1 → A AND B AND C

Step 2: Write sum-of-products expression
X = (A·B·C) + (A·B·C) + (A·B·C) + (A·B·C) + (A·B·C)
(with appropriate NOTs)

Step 3: Simplify if possible (using Boolean algebra or Karnaugh map)

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Constructing Truth Tables

From a Logic Circuit

Example Circuit:

A ──┬──[AND]──┐
B ──┘         │
           [OR]── X
C ──[NOT]─────┘

Step 1: Identify inputs (A, B, C) and output (X)

Step 2: List all possible input combinations (2ⁿ rows)

• 3 inputs = 8 combinations

Step 3: Work through circuit for each combination

A	B	C	NOT C	A·B	(A·B)+(NOT C)
0	0	0	1	0	1
0	0	1	0	0	0
0	1	0	1	0	1
0	1	1	0	0	0
1	0	0	1	0	1
1	0	1	0	0	0
1	1	0	1	1	1
1	1	1	0	1	1

From a Logic Expression

Expression: X = (A·B) + (NOT C)

Follow same process as above, evaluating expression for each input combination.

From a Problem Statement

Use the same method as “From a Problem Statement” above, but create truth table instead of circuit.

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Constructing Logic Expressions

From a Logic Circuit

Trace through circuit and write expression at each stage.

Example Circuit:

A ──┬──[AND]──┬──[OR]── X
B ──┘         │
C ──[NOT]─────┘

Step 1: Label intermediate points

• After AND gate: A·B
• After NOT gate: NOT C

Step 2: Combine at OR gate
X = (A·B) + (NOT C)

From a Truth Table

Use sum-of-products method:

1. Identify rows where output = 1
2. For each such row, write product term (AND of inputs, with NOT where input = 0)
3. Sum (OR) all product terms

Example:

A	B	C	X
0	0	1	1
0	1	1	1
1	0	0	1
1	1	0	1
1	1	1	1

Expression:
X = (A·B·C) + (A·B·C) + (A·B·C) + (A·B·C) + (A·B·C)

(With appropriate NOTs)

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Summary Checklist for Assessment Objectives

AO1 (Knowledge) – You should be able to:

• ✓ Explain need for input, output, memory, storage
• ✓ Define embedded systems with examples
• ✓ Describe operation of hardware devices
• ✓ Explain buffer purpose and function
• ✓ Differentiate RAM vs ROM
• ✓ Differentiate SRAM vs DRAM
• ✓ Differentiate PROM, EPROM, EEPROM
• ✓ Explain monitoring vs control systems
• ✓ Define logic gates and their functions

AO2 (Application) – You should be able to:

• ✓ Justify use of specific hardware for tasks
• ✓ Calculate memory requirements
• ✓ Select appropriate memory type for scenarios
• ✓ Design monitoring/control systems with sensors/actuators
• ✓ Construct truth tables from circuits/expressions
• ✓ Construct circuits from expressions/tables
• ✓ Construct expressions from circuits/tables

AO3 (Design/Evaluation) – You should be able to:

• ✓ Evaluate hardware choices for systems
• ✓ Compare and contrast memory types
• ✓ Design logic circuits for real-world problems
• ✓ Analyse feedback in control systems
• ✓ Evaluate embedded system suitability
• ✓ Optimise logic expressions

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