stucture and function of the processor

Question 1

what is the control unit ?

Answer 1

the role of the control unit is to co-ordinate all activties in the cpu

Question 2

what is the program counter?

Answer 2

the role of the program counter is to hold the address of the next instruction to be executed

Question 3

what is the memory address register?

Answer 3

the role of the MAR is holds the address of the memory location

Question 4

what is the memory data register ?

Answer 4

the role of the MDR is to store temporary data

Question 5

what is the current instruction register ?

Answer 5

the role of the CIR is to hold the address of the current instruction being executed

-opcode & operand

Question 6

what is the accumulator ?

Answer 6

this is where temporary arithmetic and logical data is stored

Question 7

what is the arithmetic logic unit ?

Answer 7

this is where all arithmetic and logical operations are performed
e.g ADD,SUB,MULT

Question 8

what is the data bus?

Answer 8

carries binary 1’s and 0’s

Question 9

what is the address bus ?

Answer 9

carries memory addresses that identify when the data is being read from or writtren to

Question 10

what is the control bus ?

Answer 10

carries control and command signals to every compartment

Question 11

Describe the Fetch-Decode-execute cycle?

Answer 11

Fetch:
- The PC is checked as it holds the address of the next instruction
-the address is stored then copied to the MAR
- The address is then sent along the address bus to main memory

Decode:
- after decoding the instruction you will be able to find out what operation you need to do next.

execute :
- now the address is sent to the MDR
- then stored in the ACC

Question 12

what is an instruction made out of ?

Answer 12

opcode + operand

opcode- what to do
operand = what to do it to

Question 13

what are common factors that affect the performance of a CPU?

Answer 13

• Clock speed = this is the amount of cycles per second

-Amount of cache = this is where temporary data is stored

-Number of cores = A cpu has multiple cores , this can speed up the CPU however they all need to communicate with each other therefore it wastes time.

Question 14

what is the pipelining technique ?

Answer 14

Pipelining is the technique of fetching an instruction whilst the prior one is being decoded and the one before that is being executed.

Question 15

Describe the von-neumann structure ?

Answer 15

• shared memory space for instruction and data
  -both stored in the same format
  -one instruction at a time

Question 16

describe the Harvard structure ?

Answer 16

-instructions and data are stored in seperate memory units
-each memory unit has its own bus
-reading and writting can be done at the same time
- used in RISC

Question 17

differences between Von-neuhmann and Harvard structure ?

Answer 17

Von-neuhmann:
- used in embedded systems
-data and programs share the same memory
-one bus is used transfer data and instructions

Havard:
- used in portabel devices
-programs and data are held in seperate memory units
- programs tend to be large

Question 18

what are registers ?
and list all 5 memory registers ?

Answer 18

registers are small memory cells that operate at high speeds.

-CIR , ACC,MDR,MAR,PC

Question 19

Describe two ways in which the accumulator is used?

Answer 19

• Used to temporarily store mathmatical and logical programs
• responsible for input and output

Question 20

state how a cpu determines if an interrupt has been raised?

Answer 20

The CPU determines if an interrupt has been raised after the program has been executed, after it has been executed, it will then detect an interrupt error.