1.1.2 Von Neumann Architecture

Question 1

Von Neumann Architecture

Answer 1

All modern CPUs are based on the Von Neumann architecture.

Question 2

ALU

Answer 2

Arithmetic and Logic Unit

Question 3

What does the ALU do

Answer 3

Performs all of the arithmetic and logical operations of the CPU eg.
Addition and subtraction, multiplication and division.
Comparisons such as whether numbers are equal or if one is greater than another.
Boolean operations (e.g. AND, OR, NOT).

Question 4

CU

Answer 4

Control Unit

Question 5

What does the CU do

Answer 5

Transmits control signals to other components of the CPU.
The Control Unit follows the fetch-decode-execute cycle to execute program instructions.
There are two main componenets of the Control Unit:
The clock, which coordinates the CPU’s activity.
The decoder, which decodes program instructions.

Question 6

Registers

Answer 6

Tiny amounts of super-quick memory within CPU.
They are used to hold information needed for the CPU to work.
Each register holds a specific piece of information.

Question 7

Types of registers in the CPU

Answer 7

ACC
MAR
PC
MDR

Question 8

ACC

Answer 8

Accumulator

Holds the result of calculations and operations performed by the ALU.

Question 9

MAR

Answer 9

Memory Address Register

Holds the address of the location in memory where data is to be retrieved or stored.

Question 10

PC

Answer 10

Program Counter

Holds the memory location address of the next instruction to be performed by the CPU.

Question 11

MDR

Answer 11

Memory Data Register

Holds the data that has been retrieved from memory, or that is about to be stored in memory.

Question 12

The Fetch, Decode, Execute Cycle (FDE)

Answer 12

Processes instructions and data, the processor needs to retrieve them from memory.

Question 13

Fetch

Answer 13

The address of the instruction that needs to be processed next is copied from the PC to the MAR.

The PC is incremented to point to the next instruction that will be needed when the cycle starts again.

The instruction stored at the location held by the MAR is copied to the MDR.

Question 14

Decode

Answer 14

The CU decodes the instruction and sends control signals to the component within or outside the CPU that needs to act.

Question 15

Execute

Answer 15

The operation indicated by the instruction is performed by the appropriate component.

The ALU performs the operation given by the CU.

The value stored by the PC or MAR might be changed.