Hardware

3.1 Computer architecture

Candidates should be able to:

1. • Understand the role of the central processing unit (CPU) in a computer
   • Understand what is meant by a microprocessor

Note and guidance

• The CPU processes instructions and data that are input into the computer so that the result can be output

• A microprocessor is a type of integrated circuit on a single chip

2. • Understand the purpose of the components in a CPU, in a computer that has a Von Neumann architecture
   • Describe the process of the fetch–decode–execute cycle including the role of each component in the process

Note and guidance

• Including:
  • units: arithmetic logic unit (ALU) and control unit (CU)
  • registers: program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR) and accumulator (ACC)
  • buses: address bus, data bus and control bus
• How instructions and data are fetched from random access memory (RAM) into the CPU, how they are processed using each component and how they are then executed
• Storing data and addresses into specific registers
• Using buses to transmit data, addresses and signals
• Using units to fetch, decode and execute data and instructions

3. Understand what is meant by a core, cache and clock in a CPU and explain how they can affect the performance of a CPU

Note and guidance

• The number of cores, size of the cache and speed of the clock can affect the performance of a CPU

4. Understand the purpose and use of an instruction set for a CPU

Note and guidance

• An instruction set is a list of all the commands that can be processed by a CPU and the commands are machine code

5. Describe the purpose and characteristics of an embedded system and identify devices in which they are commonly used

Note and guidance

• An embedded system is used to perform a dedicated function, e.g. domestic appliances, cars, security systems, lighting systems or vending machines. This is different to a general purpose computer that is used to perform many different functions, e.g. a personal computer (PC) or a laptop

3.2 Input and output devices

Candidates should be able to:

1. Understand what is meant by an input device and why it is required

Note and guidance

• Including:
  • barcode scanner
  • digital camera
  • keyboard
  • microphone
  • optical mouse
  • QR code scanner
  • touch screen (resistive, capacitive and infra-red)
  • two-dimensional (2D) and three-dimensional (3D) scanners

2. Understand what is meant by an output device and why it is required

Note and guidance

• Including:
  • actuator
  • digital light processing (DLP) projector
  • inkjet printer
  • laser printer
  • light emitting diode (LED) screen
  • liquid crystal display (LCD) projector
  • liquid crystal display (LCD) screen
  • speaker
  • 3D printer

3. • Understand what is meant by a sensor and the purposes of sensors
   • Identify the type of data captured by each sensor and understand when each sensor would be used, including selecting the most suitable sensor for a given context

Note and guidance

• Limited to:
  • acoustic
  • accelerometer
  • flow
  • gas
  • humidity
  • infra-red
  • level
  • light
  • magnetic field
  • moisture
  • pH
  • pressure
  • proximity
  • temperature

3.3 Data storage

Candidates should be able to: 1.Understand what is meant by primary storage

Note and guidance

• Primary storage is directly accessed by the CPU
• Including the role of:
  • random access memory (RAM)
  • read only memory (ROM)
• Including why a computer needs both RAM and ROM, and the difference between them

2. Understand what is meant by secondary storage

Note and guidance

• Secondary storage is not directly accessed by the CPU and is necessary for more permanent storage of data

3. Describe the operation of magnetic, optical and solid-state (flash memory) storage and give examples of each

Note and guidance

• Magnetic storage uses platters which are divided into tracks and sectors. Data is read and written using electromagnets
• Optical storage uses lasers to create and read pits and lands
• Solid-state (flash memory) uses NAND or NOR technology. Transistors are used as control gates and floating gates

4. Describe what is meant by virtual memory, how it is created and used and why it is necessary

Note and guidance

• Pages of data are transferred between RAM and virtual memory when needed

5. Understand what is meant by cloud storage

Note and guidance

• Cloud storage can be accessed remotely in comparison to storing data locally
• Physical servers and storage are needed to store data in cloud storage

6. Explain the advantages and disadvantages of storing data on the cloud in comparison to storing it locally

3.4 Network hardware

Candidates should be able to:

1. Understand that a computer needs a network interface card (NIC) to access a network

2. Understand what is meant by and the purpose of a media access control (MAC) address, including its structure

Note and guidance

• A network interface card is given a MAC address at the point of manufacture
• MAC addresses are usually written as hexadecimal
• MAC addresses are created using the manufacturer code and the serial code

3. • Understand what is meant by and the purpose of an internet protocol (IP) address
   • Understand that there are different types of IP address

Note and guidance

• An IP address is allocated by the network and they can be static or dynamic
• Including the characteristics of and differences between IPv4 and IPv6

4. Describe the role of a router in a network

Note and guidance

• A router sends data to a specific destination on a network
• A router can assign IP addresses
• A router can connect a local network to the internet