CPU REVISION

CPU REVISION

1. FDE Cycle

   • Fetch - retrieves the next instruction and associated data to be fetched from the main memory.
   • Decode - interprets the instruction then decodes it.
   • Execute - Performs the instructions, it executes it.

2. CPU Components

   • Arithmetic Logic Unit (ALU) - Part of a CPU that carries out the arithmetic and logic operations of a computer instruction
   • Control Unit (CU) - Part of a CPU that controls the flow of data within the system and to decode instructions
   • Cache - small temporary volatile memory, stores frequently used instructions, quicker for the CPU to access than main memory
   • Registers - Locations of computer memory within the processor that provide extremely fast access.

3. CPU Performance

   • Cache - ● Very fast memory, on, or very close to the CPU, stores frequently used instructions ● The holding area for data from the RAM – stores frequently used instructions. ● More cache then the better the performance. WHY? The more cache the CPU has the less time is spent accessing memory (RAM) this means it can retrieve instructions quicker and programs can run faster.
   • Cores - ● Number of independent processors within the CPU. ● Multiple Instructions able to be processed simultaneously in the same cycle. ● The more cores the quicker the performance – WHY? Quad Core = 4 cores. Can perform 4 instructions at same time in same cycle so more cycles/instructions are being processed per second
   • Clock Speed - ● Clock Speed (measured in Hertz) ● Represents the number of instructions the CPU can process in a given time. ● The higher the clock speed the faster the CPU will run, WHY? – Because it will be doing more Fetch-Decode and Execute cycles per second which means more instructions are being processed. ● A CPU with 3 GHz can run 3 billion cycles per second