general purpose computer has four main comp onents: the ari thmetic、lopic、uni t(ALU), A 、the control unit. 
the rnemory, and、the input and、output devices. The controlunit , ALU, resgisters, and、(     ) are collectivellr known as A 、central processing unit(CPU) 
A、bus 
B、basiC I/0 
C、chip 
D、memory