Edexcel GCSE Computer Science Hardware PDF

Head to www.savemyexams.com for more awesome resources Edexcel GCSE Computer Your notes Science Hardware Contents CPU Components & Their Function Von Neumann Architecture The Role of Secondary Storage Common Typ...

Head to www.savemyexams.com for more awesome resources Edexcel GCSE Computer Your notes Science Hardware Contents CPU Components & Their Function Von Neumann Architecture The Role of Secondary Storage Common Types of Storage Embedded Systems Page 1 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources CPU Components & Their Function Your notes Fetch-Decode-Execute Cycle What is the purpose of the CPU? The purpose of the Central Processing Unit (CPU) is to fetch, decode and execute instructions The CPU is the brain of the computer and its job is to take an input, process data and produce an output What is the Fetch-Decode-Execute cycle? The Fetch-Execute Cycle is the cycle that the central processing unit (CPU) runs through billions of times per second to make a computer work A computer takes an input, processes the input and then delivers an output for the user Input: Clicking a button on the gamepad Process: The CPU inside the console follows a set of instructions to carry out the task Output: The player moving on screen Page 2 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The Fetch-Decode-Execute cycle stages Fetch stage Your notes During the fetch stage of the cycle, the next instruction or data must be fetched from the computer's memory (RAM) The instruction or data is brought back to the CPU Decode stage During the decode stage of the cycle, the CPU needs to work out what is required from the instruction This could be a range of tasks depending on what the instruction or data included Execute stage During the execute stage of the cycle, the CPU will carry out the instruction that was fetched Some examples that would take place at this stage are Performing a calculation Storing a result or data back in main memory (RAM) Going to main memory to fetch data from a different location The important things to remember are: An instruction or data is fetched from memory The instruction is decoded The instruction is executed The cycle repeats billions of times per second CPU Components & Their Function What are the components of the CPU? The CPU is made up of 6 key components Arithmetic Logic Unit (ALU) Control Unit (CU) Cache Page 3 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Registers Clock Your notes Buses Each of the components sits within the CPU Page 4 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources What is the function of each component? Arithmetic logic unit (ALU) Your notes Performs arithmetic operations Performs logical decisions IF X > 5 THEN DO ………. Control unit (CU) Coordinates how data moves around the CPU by sending a signal to control the movement of the data Decodes the instructions fetched from memory Registers Extremely small, extremely fast memory located in the CPU Hold small amounts of data needed as part of the fetch-execute cycle Each register has its own specific purpose Cache Very small, very fast memory located in the CPU which is used to provide quick access to frequently used instructions and data Clock Synchronises the actions of the CPU, with each tick of the clock triggering an operation The clock speed is measured in Hertz (Hz) The clock speed measures the number of fetch-decode-execute cycles that can take place in 1 second The faster the clock speed, the more instructions can be fetched and executed per second Modern computers have a clock speed in Gigahertz (GHz), meaning billion A clock speed of 3.5GHz can perform up to 3.5 billion instructions per second Buses A bus is a set of parallel wires through which data/signals are transmitted from one component to another Page 5 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The wider a bus, the more parallel wires it has, which determines how many addressable memory locations there are Your notes There are 3 types of bus: Address - unidirectional, carries addresses data is written to/read from Data - bidirectional, carries data or instructions Control - bidirectional, carries commands and control signals to tell components when they should be receiving reads or writes etc. Worked Example Describe the role of the control unit, the control bus, the data bus and the address bus when fetching an instruction from memory Answer The address of memory (holding instruction) is placed on the address bus (1) The control unit sends a signal (1) on the control bus (to start a read operation) (1) The instruction is/the contents of the memory are placed on the data bus (1). Page 6 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Von Neumann Architecture Your notes Von Neumann Architecture What is the Von Neumann architecture? The Von Neumann Architecture is a design of the CPU which was proposed by Mathematician John Von Neumann in the 1940s, which most general-purpose computers are built upon The Von Neumann Architecture outlines how the computer memory, input / output devices and processor all work together It is known as the stored program concept, storing both programs (instructions) and data in the same memory (RAM) Main Memory Why do you need main memory? A computer needs main memory because access times are considerably faster than secondary storage Page 7 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources This means the time taken to complete operations such as the Fetch-Decode-Execute Cycle is dramatically reduced Your notes Main memory holds the data and instructions that the CPU needs to access whilst the computer is turned on Due to the fast access times, main memory is used as short term, working memory Performance of main memory means a much higher cost which limits the amount that is used For example, RAM is commonly purchased in 16 or 32 gigabytes whereas secondary storage such as a hard drive is in terabytes What is RAM? RAM (Random Access Memory) is main memory that is directly connected to the CPU and holds the data and instructions that are currently in use RAM is volatile which means the contents of RAM are lost when the power is turned off For the CPU to access the data and instructions they must be copied from secondary storage RAM is very fast working memory, much faster than secondary storage RAM is read/write which means data can be read from and written to In comparison to ROM, it has a much larger capacity What is ROM? ROM (Read Only Memory) is main memory that holds the first instructions a computer needs to start up (Bootstrap) ROM contains the BIOS (Basic Input Output System) ROM is a small memory chip located on the computers motherboard ROM is fast memory, much faster than secondary storage but slower than RAM ROM is non-volatile which means the contents of ROM are not lost when the power is turned off ROM is read only which means data can only be read from In comparison to RAM, it has a much smaller capacity Worked Example A smart television allows the user to search the Internet and watch videos online. Page 8 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The smart television uses RAM Give two examples of data that the smart television could store in RAM Your notes How to answer this question Think about the main function of a smart television, watch channels, use apps to stream content and browse the web etc. For each function, try to think of what data would have to be in the RAM whilst you were actually doing it (in use!) Possible answers Current channel being watched Current volume Current video/file/tv program being watched Web browser/applications that are running Data being downloaded/buffered Page 9 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The Role of Secondary Storage Your notes The Role of Secondary Storage Why do you need secondary storage? A computer needs secondary storage for long term storage of programs and data that are currently not in use Secondary storage is needed as ROM is read only and RAM is volatile Secondary storage holds the programs and data whilst the computer is turned off (non-volatile) Performance of secondary storage is slower than primary storage but capacity is much higher which makes it perfect for backup & archive of data files What are the characteristics of secondary storage? Capacity - What is the maximum amount of data that can be stored? Speed - How fast can data be read from and written to? (R/W) Cost - How much does it cost? Portability - How easy is it to move around? What is the physical size? Weight? Durability - How robust is the storage? Reliability - What is the probability that the device will consistently perform its function Worked Example A games console has secondary storage. State, using an example, why the games console needs secondary storage How to answer this question They keyword is 'why', why does a games console need secondary storage? give an example, do not just describe what secondary storage is! Answer To store data once the power is turned off / permanently // for non-volatile storage Examples could include: Page 10 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Storing games Save games User data / profiles Your notes Downloaded content / applications / updates Page 11 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Common Types of Storage Your notes Storage devices are non-volatile secondary storage, that retain digital data within a computer system They provide a means of storing, accessing, and retrieving data, which can include software applications, documents, images, videos, and more There are 3 types of storage: Magnetic Solid State Optical Magnetic Storage What is magnetic storage? Magnetic storage is a type of non-volatile media that uses magnets (polarity) to store binary 0s and 1s Magnetic drives contain moving parts which eventually fail Advantages Disadvantages Capacity - High storage Durability - Moving parts can get damaged if dropped Cost - Low per gigabyte Portability - Heavy & bulky making them less convenient for transport Speed - Moderate read/write Reliability - Prone to mechanical failure (moving parts) access Noise - Loud (spinning disks) Solid State Storage What is solid state storage? Solid state storage is a type of non-volatile media that uses electronic circuits to store binary 0s and 1s Solid state contain no moving parts Page 12 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Advantages Disadvantages Your notes Capacity - Medium/high storage Cost - Very high per gigabyte Speed - Very fast read/write access Reliability - Limited read/write cycles Durability - No moving parts Portability - Small and no moving parts Noise - Silent Optical Storage What is optical storage? Optical storage is a type of non-volatile media that uses lasers to burn the surface of a disk, creating pits and lands suitable for storing binary 0s and 1s Advantages Disadvantages Cost - Very low per gigabyte Capacity - Very low Durability - No moving parts Speed - Very slow read/write access Portability - Small and no moving parts Reliability - Prone to scratches Noise - Silent Suitable Storage Devices How do I choose the right storage device? Choosing the right storage device depends on: Capacity - How much data needs to be stored? Speed - How quickly can the data be read from/written to? Cost - How much does it cost? Page 13 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Portability - Does the data need to be transported? What is the physical size? Weight? Durability - How robust is the media? Your notes Reliability - Does the device to be accessed over and over again? In different scenarios, different storage devices are more suitable Scenario 1 - army laptop The army would like a new portable computer than can used whilst 'in the field', it must be robust enough to withstand a few bumps and easy to transport to new places. Money is no object In this scenario a solid state device would be most suitable A solid state device has a high durability which means it can withstand any bumps or drops, it is small in size and weight which is perfect for a device that needs to be portable and because money is no object, the high cost is not a concern Scenario 2 - school backups A school wants to backup all students work twice a day and keep it safe in case of any emergencies. The cost of the device is very important as the school budget is tight and they want a device that can hold terabytes of data in one go to minimise the amount of devices they would need to buy Page 14 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes In this scenario a hard disk drive (HDD) would be most suitable A hard disk drive has the highest capacity and would limit the amount of devices they would need to buy, it is also relatively cheap per gigabyte compared to solid state. Reliability could be an issue but as this is being used for backing up data it will not be used constantly and would be less of a concern Scenario 3 - new game release An international game studio wants to distribute it's new release for the latest games consoles. This could potential involve many millions of copies being sold so the device would have to extremely portable and cheap enough to produce so that the company do not make a loss. The device needs to be durable enough to withstand being handled regularly Page 15 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes In this scenario a Blu-ray (optical) would be most suitable A Blu-ray disc is highly portable due to its size and weight and durable enough because it has no moving parts. The cost is low which is perfect in this scenario as the company could potentially be selling millions of copies Page 16 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Embedded Systems Your notes Embedded Systems What is an embedded system? An embedded system is a computer system with a dedicated function, inside a larger mechanical unit Its purpose is to control a device and allow a user to interact with it Some embedded systems are microcontrollers meaning they are part of an integrated circuit with built in memory Embedded systems often have firmware which is software built into the system which cannot be reprogrammed by the user. Software may be able to be updated e.g. GPS software in a car navigation system Embedded systems usually have some form of analogue or digital input Automatic windscreen wipers on a car is an example of an embedded system: Rain sensors detect rain A signal is sent to the microcontroller The microcontroller sends a signal to the wiper motor (type of actuator) The wiper motor adjusts power to the motor, controlling wiper speed Examples of other embedded systems include Page 17 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Heating thermostats Hospital equipment Your notes Washing machines Dishwashers Coffee machines Satellite navigation systems Factory Equipment Traffic lights What are the properties of an embedded system? They generally use less power than a general-purpose computer, this is a major consideration for the design of an embedded system They are generally small in size They generally have a lower cost They can operate in real time and respond to inputs very quickly What is the Internet of Things? Page 18 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The Internet of Things (IoT) is a network of physical devices with the ability to transfer data without requiring human-to-human or human-to-computer interaction Your notes The IoT is made up of a vast network of embedded devices Devices could include: Consumer electronics Building sensors Wearable devices (fitness trackers etc.) Industrial machinery The advantages of the IoT include: Increased efficiency - automating tasks and processes New opportunities - evolving to create new opportunities for business & individuals Convenience - Simply daily lives by automating tasks in the home or workplace Decision making - data collected can drive decision making by providing valuable insights The disadvantages of the IoT include: Security - networked devices provide more opportunities for hackers, how secure are the devices? Privacy - Who has access to the data collected/exchanged using these devices? What actual data is collected? Where is it used? Worked Example 1) Tick two boxes below to show which are an example of an embedded system Is it an example of an embedded system Laptop Washing Machine Mobile Phone Car Engine Management System Page 19 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources 2) Justify your choice to question 1 Your notes 1) Tick two boxes below to show which are an example of an embedded system. Is it an example of an embedded system Laptop Washing Machine ✓ Mobile Phone Car Engine Management System ✓ 2) Justify your choice to question 1 Any two of: A washing machine and car engine management system are not general-purpose computers A washing machine and car engine management system have a single purpose and are both housed inside a larger mechanical unit A washing machine and car engine management system have a microcontroller Page 20 of 20 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers