1.1.1 Structure & function of the processor

Question 1

Buses

Answer 1

Data bus:

• Sends & receives data between components allowing data to flow

Control bus:

• Controls activity between components while preventing two components from using the data bus at the same time

Address bus:

• The address in RAM that the CPU is trying to read or write data from

Question 2

Arithmetic Logic Unit (ALU)

Answer 2

• The ALU performs arithmetic calculations like addition and less than allowing the program to make logical decisions

Question 3

Control Unit

Answer 3

• The control unit manages the executing instructions in the CPU and F-D-E each instruction by sending signals to other components in the CPU

Question 4

Registers

Answer 4

Registers are small amounts of fast memory used during processing on the CPU and they are volatile

• PC = Holds the address of the next instruction to be executed
• ACC = Holds the results of calculations performed by the ALU
• MAR = Holds the memory address of data read from or written to memory
• MDR = Holds data being retrieved or stored at the address held in MAR
• CIR = Holds the current instruction the processor is executing contains operand and opcode

Question 5

Factors affecting CPU performance

Answer 5

Number of cores:

• Multiple cores acts like an individual CPU processing instructions much faster in parallel

Clock speed:

• Clock speed controls the number of instructions that are processed each second measured in Hz

Cache:

• Volatile fast memory to access
• L1 cache is searched first and if data is found a cache hit occurs
• If data is not found L2 is checked and L3