Stored Program Concept and its Processing Cycle

A stored program is a program that is stored in the memory of a computer. The execution of the program then requires the use of a control unit – to read instructions from the memory at appropriate times and arrange to carry them out.

The memory used to store the program may be the same as or different from the memory used to store the data. There are advantages in using the same (read-write) memory, allowing programs to be modified, but there may be advantages in limiting opportunities for program modification, either by using physically read-only memory or by restricting access to the part of the memory containing programs.

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.