Von Neumann architucture Flashcards
Cache memory
A portion of memory used for high-speed storage
Control Unit (CU)
Internal part of the CPU and it controls the flow of data trough the CPU. It also controls interactions between the different parts of the CPU.
Immediate access store (IAS)
Memory found inside the CPU used to hold data and the instructions for the CPU. It would be very slow bringing them directly from the main memory.
Arithmetic logic unite (ALU)
Internal part of CPU that carries out calculations on data. Values must be placed in the accumulator for calculations to be carried out.
Registers
Internal memory locations within the CPU. They hold data and instructions during the process. Registers are used to move data and instructions into and around the different components of the CPU.
Input/Output
Allows interaction with the computer. Instructions are processed from and to them in the CPU.
Buses
A series of conductors, which deliver data and the instructions to different components.
The fetch-execute cycle
1 Fetching the instruction
2 Decoding the instruction
3 Executing the instruction
Fetching the instruction (1)
- The CPU puts the address of the next item that needs to be fetched on the address bus
- The data from this address is then moved from main memory into IAS by data bus
- Registers are then used to store and move the data to a special register that will decode the instructions
Decoding the instruction(2)
The CPU is designed to understand a specific set of commands. This is called a instruction set and the CPU uses this in order to decode the instruction.
Executing the instruction(3)
In this stage, the CPU understands the instruction and carries it out. If any arithmetic calculations are needed in the instructions, they are carried out by ALU. Once the instruction is done, the cycle begin again for next instruction.
