OCR GCSE computer science

What is the purpose of the CPU?

executing instructions given in a program, where data process is, control other device(fetch-execute cycle)

What are the common CPU components?

ALU, CU, Cache, registers

What happens in the fetch part of the cycle?

instruction/data to be used moved from RAM to CPU, CPU send signal, request next instruction/data to be used.

What happens in the execute part of the cycle?

CU decode/interpret instruction&decide what it mean&action to perform, then it carry out. If calc need to be perform, CU instruct ALU.

What is the MAR?

holds address(loction in mem)of instruction/data to be fetch/stored

What is the MDR?

holds data/program instruction temporarily when fetch(mem)/data to be fetch/stored.

What is the program counter(PC)?

holds mem address of next instruction to be process

what is the Accumulator(ACC)?

memory location where operation carry out by ALU are temporary stored.

What is the cache?

temporary data/instruct store(likely need by CPU), so can be access quick when need

What is the ALU?

perform arithmetic/logic operation(+/-/*/division/logical test using logic gate/comparison/shift operation).

What is the Control Unit(CU)?

coordinate act in CPU, also of computer&control fetch-execute cycle by send control sig to parts of CPU. also send sig to other components of computer system.

What is the von neumann architecture?

hold both program/data in memory. Data would move between mem unit and CPU.

What happened before the von neumann architecture?

computer had to be rebuilt for each new program needed.

What way does the von neumann architecture execute program instructions?

fetch-execute cycle

What is the way the CPU is designed and executes program instructions called?

von neumann architecture

What is clock speed measured in?

cycles per second(hertz/Hz)

What is the speed at which CPU operates at called?

clock speed

What is the clock?

pulses sent to components to coordinate their act&ensure instruct carry out&complete. one instruct carry out with each pulse.

main factors affecting CPU performance?

clock speed, cache size, number of cores

What is the fastest cache size?

level 1 cache(L1), but the smallest memory capacity out of 2 more cache’s

How does cache help modern computers without increasing price?

increases speed at minimal costs.

What is a multi core processor?

has more than one CPU

Pros of multi cores?

work together on same program(parallel processing), work on diff programs at same time(multi-tasking)

cons of multi cores?

may not work together at same time on program, so tasks carried out in turns.