Hardware Flashcards
central processing unit (cpu)
processes instructions and data that are input into the computer so that the result can be
output
control unit (CU)
manages other components of the cpu and overall operation (including fetch-decode-execute cycle and ALU)
arithmetic logic unit (alu)
responsible for carrying ou mathematical operation (eh bit shifts)
why dos alu use accumulator (acc)
temporarily store the data while performing calculations
registers
small areas of storage found within cpu (PC, MAR, MDR, CIR, ACC)
pc
program counter - holds the address of the next instruction to be fetched
mar
memory address register - used when reading or writing data from/to ram
mdr
memory data register - used to read/write from/to ram. mdr contains data while mar contains address
cir
current instruction register - holds the instruction which is currently being decoded or executed
acc
accumulator - used to hold data being worked on by alu
bus
way of communicating between components
how many buses does cpu have
3 (control, address, data)
control bus
carries control signals from the control unit to other components of the cpu
address bus
carries addresses from mar to ram to indicate which address will b selected
address bus is
unidrectional
data bus
carries thee data to be written from the mdr to ram
the data bus is
bidirctional
fetch-decode-execute cycle
cycle computer follows to run programs
active computer programs are stored in the
ram
fetch steps
- PC contains the location of the next instruction
- This address is copied to the MAR.
- pc is incremented by 1 so that it points to next instruction
- address bus carries value in mar to ram
- control bus sends read signal to ram
- contents of mdr are copied to cir
decode steps
cu decodes instruction in cir
execute steps
- instruction is sent to alu to be executed
- alu may use acc to temporarily store its results
factors that affect cpu performance
clock speed, cores, cache
clock speed
- determines number the cycles cpu can perform each second (measured in gigahertz)
- higher clock speed -> more heat -> more energy