Central Processing Unit (CPU)

• The Central Processing Unit (CPU) fetches, decodes, and executes instructions.
• The CPU is the core of a computer which intakes, processes, and outputs data.
• CPUs are used in laptops, desktops, game consoles, and mobile devices.
• The terms CPU and Microprocessor are interchangeable.
• A microprocessor is a type of integrated circuit on a single chip.
• The CPU processes data by executing instructions inputted by the user, and results are outputted to an output device.

Clock Speed

• Measured in Hertz (Hz).
• Determines the number of fetch-decode-execute cycles per second.
• The faster the clock speed, the more instructions processed per second.
• Modern computers have clock speeds in Gigahertz (GHz), i.e. billions of cycles per second.
• A clock speed of 3.5GHz can perform up to 3.5 billion instructions per second.

Cache

• Cache is small, very fast memory on or near the CPU.
• Cache is temporary storage for quick access to frequently used instructions and data.
• A larger cache size allows more frequently used instructions/data to be stored.
• Reduces fetch cycles from RAM, speeding up performance.
• Cache has faster read/write speeds than RAM.

Cores

• A core functions as its own CPU.
• Multi-core processors have multiple processing units that can simultaneously fetch, decode, and execute instructions.
• A dual-core processor has 2 processing units, each with their own: Control Unit (CU), Arithmetic Logic Unit (ALU), Accumulator (ACC), and Registers.
• Multi-core processors can run more powerful programs more easily.
• Multiple cores increase CPU performance in conjunction with clock speed.
• A quad-core CPU (4 cores) running at 3GHz can perform 12 billion instructions per second (4 cores x 3 billion instructions).