1.1 - CPU Flashcards
What does a computer do
takes inputs and performs functions to produce an output
What does I - P - O stand for
Input Process Output
What are the three parts of a cycle
Fetch Decode Execute (FDE cycle)
What is a register
a small, fast bit of memory within the CPU
What does the program counter (PC) do
stores which instruction is next
What does the memory address register (MAR) do
stores the address in RAM that needs to be fetched
What does the memory data register (MDR) do
stores the instruction/data that has been fetched from RAM
What does the current instruction register (CIR) do
stores which instruction is being processed
What does the accumulator (ACC) do
stores the results of calculations
Summarise Fetch stage of FDE cycle
The memory address from PC is copied to MAR, PC increases by 1, instruction/data from correct address in RAM is stored in MDR
Summarise Decode stage of FDE cycle
Instruction/Data is copied from MDR to CIR if it is an instruction, from the MDR to the MAR if it is an address, or from the MDR to the ACC if it is a number. The control unit works this out.
Summarise Execute stage of FDE cycle
The instruction goes to the ALU which performs maths/logic. the output is stored in the ACC
what are the 6 main parts of the CPU
control unit (CU), arithmetic logic unit (ALU), registers, cache, clock, buses
What three things increase CPU performance
more cache, higher clock speed, more cores
What is cache
small amounts of high speed memory closer to the CPU
