computer architecture

The purpose of the CPU is to fetch, decode and execute instructions.

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

CPU stands for Central Processing Unit.

False. The CPU is used in various devices including laptops, desktops, games consoles, and mobile devices.

Data and commands inputted by the user using an input device.

The execution of instructions by the CPU to manipulate data.

The results of processing displayed to the user via an output device.

The three main steps in computer data processing are input, process, and output.

True. The terms CPU and microprocessor can be used interchangeably.

The Von Neumann Architecture is a design of the CPU proposed by John Von Neumann in the 1940s, which most general-purpose computers are built upon.

Holds the memory address of the next instructions to be executed.

Holds the memory address of where data or instructions are to be fetched from in memory.

Stores the data or instruction which has been fetched from memory.

Stores the instruction the CPU is currently decoding or executing.

Stores the results of any calculations that have taken place in the Arithmetic Logic Unit (ALU).

A bus is a set of parallel wires through which data/signals are transmitted from one component to another.

The three types of buses are address bus, data bus, and control bus.

The address bus carries location data (addresses), data is written to/read from.

False. The data bus is bidirectional, carrying data or instructions in both directions.

The Fetch-Decode-Execute Cycle is the cycle that the central processing unit (CPU) runs through billions of times per second to make a computer work.

The three main stages are Fetch, Decode, and Execute.

In the fetch stage, the Program Counter (PC) holds the address of the next instruction to be fetched from memory.

The Program Counter increments by 1 so it is pointing to the next instruction to be executed.

The part of an instruction that specifies what operation to perform.

The part of an instruction that specifies what to perform the operation on.

During the decode stage, the CPU works out what is required from the instruction by splitting it into opcode and operand.

False. The execute stage can involve performing a calculation, storing a result, or fetching data from memory, depending on the instruction.

The Control Unit sends a signal along the control bus to initiate the read operation from main memory.

A modern CPU typically performs the Fetch-Decode-Execute cycle billions of times per second.

The three common characteristics are:

Clock speed is measured in Hertz (Hz) and measures the number of fetch-decode-execute cycles that can take place in 1 second.

True. Modern computers have a clock speed in Gigahertz (GHz), meaning billions of cycles per second.

The faster the Clock Speed, the more instructions can be fetched and executed per second.

A Clock Speed of 3.5GHz means it can perform up to 3.5 billion instructions per second.

Cache is used as temporary storage to provide quick access to frequently used instructions and data.

The larger the Cache Size, the more frequently used instructions or data can be stored, resulting in fewer fetch cycles from RAM and improved performance.

Each core works like its own CPU, so multiple cores allow multiple processing units to fetch, decode and execute instructions simultaneously.

False. A dual-core CPU (2 cores) running at 3.6GHz can perform 2 x 3.6 billion instructions = 7.2 billion instructions per second. A quad-core CPU (4 cores) running at 2.5GHz can perform 4 x 2.5 billion instructions = 10 billion instructions per second.

For a dual-core processor, "dual-core" means there are two cores (processing units) that can fetch, decode and execute instructions.

An instruction set is a list of all the commands that can be processed by a CPU.

The binary code representation of a CPU instruction.

The two parts of a machine code instruction are the operation code (opcode) and the operand.

A mnemonic is a short, human-readable code that represents a machine code instruction.

False. Instruction sets are machine-specific and can vary between different processor manufacturers.

The ADD instruction typically adds a value to the value currently stored in the accumulator (ACC).

The LDA instruction typically loads the value stored in a memory location into the accumulator.

The HLT instruction (halt) typically stops the program.

An embedded system is a computer system with a single function, inside a larger mechanical unit.

Examples of embedded systems include:

The three key properties of an embedded system are:

False. A laptop is not an example of an embedded system. A laptop is an example of a general-purpose computer.

They have a single dedicated function rather than being general-purpose computers.

False. While a fridge has a single main function, it does not contain a CPU, so it is not considered an embedded system.

No. Mobile phones are general-purpose computing devices, not single-function embedded systems.