The Von Neumann and Harvard architectures are two common computer architectures. The Von Neumann architecture uses a single memory to store both programs and data, accessed via a shared bus, while the Harvard architecture separates memory and uses two separate buses for program and data access. The Von Neumann architecture has advantages of simpler design and lower cost while the Harvard allows parallel instruction and data processing but has higher development costs. They differ primarily in their memory structure and bus configurations.

1. • Define Von Neumann and Harvard Architectures in
detail.
• List the advantages and disadvantages of each.
• State their differences.
Olson Matunga B1233383 Bsc Hons.
Comp Science

2. 
 Between 1945 & 1951 John von Neumann set down the
structure, layout, interaction, cooperation, realisation,
implementation, functionality and activity for the whole
computer as a system. The Von Neumann Architecture is
characterized by: -
 A memory, arithmetical-logical unit (ALU), control
unit, input and output devices,
 All parts of a computer are connected together by Bus,
 Memory and Devices are controlled by CPU.
 Data can pass through bus in half duplex mode to and
from CPU.
Von Neumann Architecture
Olson Matunga B1233383 Bsc Hons.
Comp Science

3. 
 Memory holds both programs and data; this is also known
as the stored program concept.
 Memory is addressed linearly; that is, there is a single
sequential numeric address for each and every memory
location.
 Memory is addressed by the location number without
regard to the data contained within.
 Memory is split to small cells with the same size. Their
ordinal numbers are called address numbers.
Von Neumann Architecture
Cnt’d
Olson Matunga B1233383 Bsc Hons.
Comp Science

4. 
 Program consists of a sequence of instructions.
Instructions are executed in order they are stored in
memory.
 Sequence of instructions can be changed only by
unconditional or conditional jump instructions.
 Instructions, characters, data and numbers are represented
in binary form.
Von Neumann Architecture
Cnt’d
Olson Matunga B1233383 Bsc Hons.
Comp Science

5. 
Diagrammatic view of Von
Neumann Architecture
Olson Matunga B1233383 Bsc Hons.
Comp Science

6. 
 Control Unit gets data and instruction in the same way
from one memory. It simplifies design and development of
the Control Unit.
 Data from memory and from devices are accessed in the
same way.
 Memory organization is in the hands of programmers.
Advantages of Von
Neumann
Olson Matunga B1233383 Bsc Hons.
Comp Science

7. 
 Serial instruction processing does not allow parallel
execution of program. Parallel executions are simulated
later by the Operating system.
 One bus is a bottleneck. Only one information can be
accessed at the same time.
 Instruction stored in the same memory as the data can be
accidentally rewritten by an error in a program.
Disadvantages of Von
Neumann
Olson Matunga B1233383 Bsc Hons.
Comp Science

8. 
 MARK II computer was finished at Harvard University in
1947. It wasn't so modern as the computer from von
Neumann team. But it introduced a slightly different
architecture. Memory for data was separated from the
memory for instruction. This concept is known as the
Harvard architecture.
Harvard Architecture
Olson Matunga B1233383 Bsc Hons.
Comp Science

9. 
Diagrammatic view of
Harvard Architecture
Olson Matunga B1233383 Bsc Hons.
Comp Science

10. 
 since it has two memories , this allows parallel access to
data and instructions.
 Development of the Control Unit is expensive and needs
more time
 Data and instructions are accessed the same way.
 Both memories can use different cell sizes.
Advantages of Harvard
Olson Matunga B1233383 Bsc Hons.
Comp Science

11. 
 Free data memory cant be used for instruction and vice-
versa.
 Production of a computer with two buses is more
expensive and needs more time.
Disadvantages of Harvard
Olson Matunga B1233383 Bsc Hons.
Comp Science

12. 
Harvard vs von Neumann
Harvard
 Two memories with two Buses
allow parallel access to data
access and instructions.
 Control unit for two buses is
more complicated and more
expensive.
 Program cant write itself.
 Both memories can use
different sizes.
Von Neumann
 Content of the memory if
organised and all installed
memory can be used.
 One bus is simpler for the control
unit design
 Computer with one bus is cheaper.
 Error in a program can rewrite
instruction and crash program
execution.Olson Matunga B1233383 Bsc Hons.
Comp Science

13. 
Harvard vs von Neumann
Harvard
 Development of a
complicated Control Unit
needs more time.
 Free data memory can’t
be used for instruction and
vice-versa.
Von Neumann
 Development of the Control
Unit is cheaper and faster.
 Data and instruction is
accessed in the same way.
 One Bus ( for Data,
instruction and devices) is a
bottleneck.
Olson Matunga B1233383 Bsc Hons.
Comp Science

14. 
Harvard architecture is used primary for small
embedded computers
and signal processing (DSP).
Von Neumann is better for desktop
computers, laptops, workstations and high
performance computers.
Olson Matunga B1233383 Bsc Hons.
Comp Science

15. 
THE END
THANK
YOU
Olson Matunga B1233383 Bsc Hons.
Comp Science