1.1 - Systems Architecture Flashcards
What is inside the CPU?
- Arithmetic Logic Unit (ALU)
- Control Unit (VU)
- Cache
- Registers
What does the Arithmetic Logic Unit (ALU) do?
Carries out maths and logic calculations
What does the Control Unit (CU) do?
Coordinates the FDE cycle and decodes instructions
What is cache?
Small, fast memory that holds frequently accessed items
What are the 4 registers?
- Memory Address Register (MAR)
- Memory Data Register (MDR)
- Program Counter
- Accumulator
What does the Memory Address Register (MAR) hold?
Address of where will be written / is being fetched to
What does the Memory Data Register (MDR) hold?
Instruction/data that will be written / has been fetched to
What does the Program Counter hold?
Address of the next instruction to be fetched from memory
What does the Accumulator hold?
Results from Arithmetic Logic Unit (ALU) calculations
What happens in the fetch stage of the FDE cycle?
- Instruction is fetched from memory using the address in the Program Counter
- Program Counter changes to the next instruction’s address
What happens in the decode stage of the FDE cycle?
Instruction is interpreted by the Control Unit
What happens in the execute stage of the FDE cycle?
- Instruction is carried out
- Any additional data is fetched
- Results may be written to memory
What are the characteristics of the CPU?
- Clock Speed
- Number of Cores
- Cache Size
What is Clock Speed?
The rate at which the FDE cycle is carried out (GHz)
What does having more cores do?
If software allows it, each core can execute an instruction at the same time, increasing the speed of the CPU
