von neumann architecture

Question 1

von neumann architecture

Answer 1

the design upon which many general purpose computers are based. This architecture uses the stored program concept

Question 2

how are data and instructions stored

Answer 2

as binary digits

Question 3

where are data and instructions stored?

Answer 3

in the RAM

Question 4

where are instructions fetched from, and how?

Answer 4

they are fetched from memory, one at a time (serially)

Question 5

what does the processor do?

Answer 5

it decodes and executes an instruction, before cycling around to fetch the next instruction

Question 6

when does the cycle stop?

Answer 6

until there are no more instructions available

Question 7

what are the key elements of von neumann architecture

Answer 7

1. data and instruction turned into binary
2. data and instructions stored in RAM
3. instructions fetched from memory serially
4. processor decodes and executes instruction before fetching the next one
5. cycle continues until instructions are finished

Question 8

what are the 5 special registers that a processor uses when processing

Answer 8

1. program counter
2. MAR
3. MDR
4. CIR
5. ACC

Question 9

program counter

Answer 9

holds the memory address of the next instruction to be fetched from main memory

Question 10

MAR

Answer 10

memory address register- holds the address of the current instruction that is to be fetched from the memory

Question 11

MDR

Answer 11

memory data register- holds the contents found at the address held in the MAR, or data which is to be transferred to main memory

Question 12

CIR

Answer 12

current instruction register- holds the instruction that is currently being decoded and executed

Question 13

ACC

Answer 13

accumulator- holds the results of processing

Question 14

the fetch-decode-execute cycle

Answer 14

the cycle that the central processing unit follows from boot-up until the computer has shut down in order to process instructions

Question 15

steps of the fetch-decode-execute cycle

Answer 15

1. the memory address held in the program counter is copied into the MAR
2. the address in the program counter is then incremented - or increased - by one. The program counter now holds the address of the next instruction to be fetched
3. the processor sends a signal containing the address of the instruction to be fetched along the address bus to the computers memory
4. the instruction held in the memory address is sent along the data bus to the MDR
5. the instruction held in the MDR is copied into the CIR
6. the instruction held in the CIR is decoded and then executed. The results of processing are stored in the ACC
7. the cycle then returns to step one

Question 16

additional steps may be taken depending on the type of instruction,
if the instruction is to transfer data held in the ACC back to the RAM:

Answer 16

the intended memory address is copied into the MAR. The data to be transferred is copied into the MDR and then transferred to the specified address using the address bus data bus.