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neurologyYou need to know

• The central processing unit (CPU) processes data and instructions by repeatedly carrying out the fetch-execute cycle.
• The fetch-execute cycle has three main stages: fetch the next instruction from memory, decode the instruction, and execute it.
• During the fetch stage, the CPU retrieves the next instruction from main memory using its stored memory address.
• During the decode stage, the control unit interprets the instruction and determines the operation that must be performed.
• During the execute stage, the CPU carries out the decoded instruction, which may involve a calculation, logical comparison, data movement or input/output operation.
• The arithmetic logic unit (ALU) performs arithmetic calculations and logical operations, including comparisons.
• The control unit (CU) coordinates the CPU by decoding instructions and sending control signals to other components.
• Cache is small, fast memory located in or close to the CPU that stores frequently or recently used data and instructions.
• Registers are very small, high-speed storage locations inside the CPU that temporarily hold data, instructions or memory addresses.
• In Von Neumann architecture, program instructions and data are stored together in the same memory and use the same communication pathways.
• The memory address register (MAR) stores the address of the location in memory that the CPU needs to access.
• The memory data register (MDR) stores data or instructions being transferred to or from memory.
• The program counter (PC) stores the memory address of the next instruction to be fetched.
• The accumulator stores intermediate data and the results of calculations performed by the ALU.
• An address identifies a location in memory, whereas data is the information or instruction stored at that location.
• Clock speed is the number of CPU cycles completed per second, measured in hertz, and a higher clock speed can allow more instructions to be processed in a given time.
• A larger cache can improve CPU performance by reducing how often the CPU must access slower main memory, although the benefit depends on whether the required data and instructions are cached.
• A processor core is an individual processing unit within a CPU, and multiple cores can execute instructions simultaneously when software supports parallel processing.
• CPU performance depends on the combined effects of clock speed, cache size, number of cores, software design and the type of tasks being processed.
• An embedded system is a computer system built into a larger device to perform a specific function, often with limited hardware resources, low power consumption and little or no user reprogramming; examples include washing machines, traffic lights, vehicle engine-management systems, digital thermostats and pacemakers.

• Sequence the fetch, decode and execute stages and describe the action that occurs at each stage.
• Identify the ALU, control unit, cache and registers in a CPU description and explain each component’s function.
• Match the MAR, MDR, program counter and accumulator to what each register stores, distinguishing addresses from data or instructions.
• Explain how changing clock speed, cache size or number of cores can affect CPU performance, including limitations such as software support for multiple cores.
• Compare two CPUs using their clock speed, cache size and number of cores, avoiding the assumption that one characteristic alone always determines performance.
• Classify a device as an embedded system by linking its dedicated function to characteristics such as limited resources, low power consumption and restricted user control.
• Give and justify examples of embedded systems from household, transport, medical and industrial contexts.