1.1.1e - Processor Architecture

Question 1

What is the Von Neumann Architecture?

Answer 1

A computer architecture where program data and instruction data are stored in the same memory. (1945)

Question 2

Features of the Von Neumann Architecture

Answer 2

• It is ancient computer architecture based on stored program computer concept
• The same physical memory address is used for both instructions and data
• There is a common bus for data and instruction transfer
• Two clock cycles are required to execute a single instruction
• It is cheaper in cost
• CPU can not access instructions and read/write at the same time
• It is used in personal computers and small computers

Question 3

What is the Harvard Architecture?

Answer 3

A computer architecture where there are separate memory locations and buses for instruction and data.

Question 4

Features of the Harvard Architecture

Answer 4

• It is modern computer architecture based on the mark I relay based model
• Separate physical memory address is used for instructions and data
• Separate buses are used for transferring data and instruction
• An instruction is executed in a single cycle
• It is more costly than Von Neumann Architecture
• CPU can access instructions and read/write at the same time
• It is used in micro controllers and signal processing

Question 5

Advantages of Von Neumann Architecture (3 points)

Answer 5

• Simplicity: all of the data and instructions being stored in one location means less complicated systems are required as pathways (buses) are shared
• Cost Effective: a smaller number of components are required therefore making it more economical
• Flexibility: a program can always be altered without a requirement to change physical aspects such as circuitry

Question 6

Disadvantages of Von Neumann Architecture (3 points)

Answer 6

• Bottleneck issues: the shared bus can be a problem because the data and control instructions cannot be obtained simultaneously and therefore it becomes slow.
• Memory corruption: Since the data and instructions reside in the same memory, then there is a temptation for one to erase the other, producing system faults.
• Memory leaks: some defective programs fail to release memory when they are finished with it, which could cause the computer to crash due to insufficient memory.

Question 7

Advantages of the Harvard Architecture (3 points)

Answer 7

• Fast and efficient data access: the separate memory spaces for instructions and data allow for parallel and simultaneous access to both memory spaces.
• Improved security: The chance of memory corruption is at least cut in half since data is not stored in the same location as instructions.
• Efficient use of instructions: it enables the use of different memory for data and for instructions of different sizes as this helps in optimal utilization of the buses and other resources.

Question 8

Disadvantages of the Harvard Architecture (3 points)

Answer 8

• Complexity: the design and implementation of this design are more intricate than Von Neumann.
• Higher cost: having two sets of memory and two separate buses makes the implementation costs much higher than Von Neumann.
• Less flexibility: changing or improving the system can be challenging due to the different memory regions.