Processor Implementation

Question 1

Processor main parts

Answer 1

datapath

control

Question 2

datapath

Answer 2

caries out arithmetic and other operations, moves operands and results around

Question 3

control

Answer 3

task to determine the appropriate value of each control unit within the datapath

Question 4

datapath components include

Answer 4

ALU, registers, cache memory, multiplexors, plus others

Question 5

time for one step of a machine language instructions to execute

Answer 5

one clock cycle

Question 6

delimiting steps

Answer 6

use storage elements that are stored in such a way that the stored values can change only at the end of a clock cycle

Question 7

combinational circuits

Answer 7

output is only a function of the current input

Question 8

sequential circuits

Answer 8

output depends both on the current input and on the current circuit “state” (value stored), as set by previous inputs

Question 9

S-R latch

S=1, R=0

Answer 9

store a 1 in the circuit (the output Q=1)

Question 10

S-R latch

S=0, R=1

Answer 10

store 0 in the circuit

the output Q=0

Question 11

S-R latch

S=0, R=0

Answer 11

Cause no change to stored value

Question 12

D latch

C input = 0

Answer 12

no change to the stored value

Question 13

D latch

C input = 1

Answer 13

D input value is stored

Question 14

D flip-flop

The D input value is stored when

Answer 14

only when the clock input C changes from 1 to 0

Question 15

Using D flip-flops we can build

Answer 15

storage elements whose stored values can change only at the end of a clock cycle

Question 16

Simple single clock cycle datapath

Answer 16

each instruction executes in a single clock cycle
contains only
    * PC register
    * adder for incrementing PC by 4
    * instruction memory component
    * register file
    * an ALU

Question 17

The clock cycle must be long enough so

Answer 17

the adder, register file, memory, ALU, all have time to do their work

Question 18

Control units within the datapath includes

Answer 18

• read/write enable control inputs for storage elements
• selector inputs for multiplexors
• ALU control units

Question 19

Control for single clock cycle datapath

Answer 19

uses op and funct fields from instruction