Systems Architecture Flashcards
def computer
elec device that takes input, processes data, and deliver output
fetch cycle
fetch instruction from main mem
bring back to cpu
decode cycle
inspect instruction, work out what needs to be done
execute cycle
carry out instruction
e.g grab more data from ram
perform claculation
storing info back into ram
how often fetch decode execute cycle occur
billion time per second.
called the clock speed
clock speed
measured in Hz
1hz = 1 cycle per sec
3GHz = 3bn cycles/sec
alu job
arithmetic claculations
making logical decisions
control unit job
send signals to control how data moves around cpu
cache
very fast memory used to store insturctions and data
very close to cpu or right inside it
registers
tiny super fast memory in cpu
each has specific purpose
internal clock of cpu job
provides pulse constant rate to syncronise components
FETCH STAGE IN DETAIL
program counter checked as it holds address of next instruction 2 b executed.
address used by MAR to feth instruction from RAM and bring it to MDR
addrsss in program coutner incremented to point to next instruction
DECODE STAGE
control unit decodes instruction to see what is to be done
EXECUTE STAGE
instruction executed
cache size - how it affect cpu perofrmance
temporary storage of data/instructions being to and written from
on or very near cpu
stories coipies of recent data/instruct
much quicker to get data from cache than ram - saves time
