for the students who are learning computer organisation as their subject of study and will be too helpful for them

1. Stored program concept
Storage of instructions in computer memory to enable it to
perform a variety of tasks in sequence or intermittently.
The idea was introduced in the late 1940s by John von Neumann,
who proposed that a program be electronically stored in binary-
number format in a memory device so that instructions could be
modified by the computer as determined by intermediate
computational results.
 Other engineers, notably John W. Mauchly and J. Presper Eckert,
contributed to this idea, which enabled digital computers to become
much more flexible and powerful. Nevertheless, engineers in England
built the first stored-program computer, the Manchester Mark I,
shortly before the Americans built EDVAC, both operational in 1949.
A CPU chip can handle billions of instructions per second, and as
long as the instructions are valid and reference data within the
program's boundaries, the control unit executes them. If not, the
computer stops running the program

2. Stored program concept
 The Manchester Small-Scale Experimental Machine (SSEM),
nicknamed Baby, was the world's first stored-program computer. It was
built at the Victoria University of Manchester, England, by Frederic C.
Williams.
 Following things will come under:-
1In the stored program concept, both the instructions and the data (that
the instructions operate on) are stored in the computer memory itself.
Before the introduction of this idea, instructions and data were
considered two totally different entities and were thus stored
separately.
2Thus instructions like data can be read from the memory and written to
the memory by the processor.
3The processor then addresses the memory, reads the corresponding
instructions, executes them and according to the executed instruction,
processes (reads and writes) data as well.
4Computers that store both instructions and data on the same memory
are said to be based on the Von Neumann architecture. Modern
desktop computers are still based on the same stored program concept.

3. Stored program concept

4. Stored program concept
Von Neumann Architecture
 also known as the Von Neumann model, the computer consisted
of a CPU, memory and I/O devices. The program is stored in the
memory. The CPU fetches an instruction from the memory at a
time and executes it.
Thus, the instructions are executed sequentially which is a slow
process. Neumann m/c are called control flow computer because
instruction are executed sequentially as controlled by a program
counter. To increase the speed, parallel processing of computer
have been developed in which serial CPU’s are connected in
parallel to solve a problem. Even in parallel computers, the basic
building blocks are Neumann processors.
The von Neumann architecture is a design model for a stored-
program digital computer that uses a processing unit and a single
separate storage structure to hold both instructions and data. It is
named after mathematician and early computer scientist John von
Neumann.

5. Stored program concept
An accumulator is a register for short-term, intermediate storage of
arithmetic and logic data in a computer's CPU (central processing unit).

6. Stored program concept
Memory
The computer will have memory that can hold both data and also
the program processing that data. In modern computers this
memory is RAM.
Control Unit
The control unit will manage the process of moving data and
program into and out of memory and also deal with carrying out
(executing) program instructions - one at a time. This includes the
idea of a 'register' to hold intermediate values. In the illustration
above, the 'accumulator' is one such register.
The 'one-at-a-time' phrase means that the von neumann
architecture is a sequential processing machine.
Input - Output
This architecture allows for the idea that a person needs to interact
with the machine. Whatever values that are passed to and forth
are stored once again in some internal registers.

7. Stored program concept
Arithmetic Logic Unit
This part of the architecture is solely involved with carrying out calculations
upon the data. All the usual Add, Multiply, Divide and Subtract calculations will
be available but also data comparisons such as 'Greater Than', 'Less Than',
'Equal To' will be available.
Bus
Notice the arrows between components? This implies that information should
flow between various parts of the computer. In a modern computer built to
the Von Neumann architecture, information passes back and forth along a
'bus'. There are buses to identify locations in memory - an 'address bus'
And there are buses to allow the flow of data and program instructions - a 'data
bus'.
Conclusion
• The Von Neumann architecture has been incredibly successful, with most
modern computers following the idea. You will find the CPU chip of a personal
computer holding a control unit and the arithmetic logic unit (along with some
local memory) and the main memory is in the form of RAM sticks located on
the motherboard.