cpu

Question 1

Describe the purpose of the CPU

Answer 1

consists of components of the computer that processes instructions (logical op/simple arithmetic)
program instructions are interpreted and executed in CPU

Question 2

What must a computer be able to do to process data?

Answer 2

input data and instructions
store data and instructions (a memory)
output results of the processing
control and interpret machine language and send appropriate signals to different parts of the computer

Question 3

Describe the control unit.

Answer 3

sends and receives signals from and to different parts of the comouter
supervises the fetch decode execute cycle
ensures all data and instructions are processed at the right time, in the right order
directs the flow of data and instructions

Question 4

Describe the Arithmetic and logic unit.

Answer 4

processes and manipulates data

performs simple arithmetic calcs and logic operations e.g. comparing values

Question 5

Why are registers required in the CPU?

Answer 5

to store results from ALU

for the CU to store details of operations being dealt with by fde cycle

Question 6

Describe what registers are.

Answer 6

Temporary fast access storage location
in the cpu
where info is temporarily stored

Question 7

What is a con of registers?

Answer 7

It has a limited storage capacity

Question 8

Describe CIR

Answer 8

current instruction register

it stores the instruction currently being executed

Question 9

Describe PC

Answer 9

program counter

it s stores memory location of the next instruction needed by the processor

Question 10

Describe MAR

Answer 10

memory address register

stores memory location of where data is being read from or written to

Question 11

Describe ACC

Answer 11

Accumulator

stores the results from the calculations made by ALU

Question 12

What are buses?

Answer 12

pathways that use groups of parallel wires to transfer data from one location in the computer to another

Question 13

Describe the data bus.

Answer 13

carries data and instruction to and from the processor and memory, as program is run
carries data both ways (to and from memory)(to and from I/O controllers)

Question 14

Describe the address bus.

Answer 14

carries data in one direction
from processor to memory
carries the memory address of the next instruction or data item
used to access anything stored in memory to the processor

Question 15

Describe the control bus

Answer 15

helps the CU communicate with other parts of the computer
delivers control information on time to the CU, at the right place
one way but can at times be both directions

Question 16

Describe internal memory

Answer 16

the memory built into a computer
rom, ram, registers
fast accessed memory is directly accessed by the processor

Question 17

Describe the fetch stage

Answer 17

copy of address in PC is sent to the MAR
processor uses address to find instruction in memory
contents of that data in memory is sent to cir
pc moves on one point
cycle repeats until all instructions are carried out

Question 18

Describe the decode stage

Answer 18

CU checks instruction in the CIR

instruction is decoded to determine the action to be carried out

Question 19

Describe the execute stage

Answer 19

processor carries out the instruction

next instruction is fetched