The von Neumann architecture is used in most computers.
Explain one feature of the von Neumann stored program concept.
Mark scheme
Award up to two marks for a linked explanation such as:
- The instructions/program instructions and data are stored together in main memory/RAM (1) so the CPU can fetch each instruction (from its address) and execute it (1)
- The instructions/program instructions are held in main memory/RAM (1) rather than being built into/part of the hardware, so the computer does not need to be rewired/rebuilt to run a different program (1)
- The next instruction to be executed/instruction is held in main memory/RAM (1) so the CPU can fetch it using its address before it is decoded and executed (1)
For both marks, the expansion must follow/associate with the statement.
A point/statement on its own can only earn one mark.
Do not accept a response that only refers to data being stored in main memory/RAM without referring to the instructions/program instructions.
Do not accept instructions/programs being stored on the hard disk/backing store.
Do not accept 'the program is stored in memory' without saying that it is the instructions/program instructions that are stored there.
Example answers and how they were marked
Both the instructions of the program and the data it uses are stored together in the same main memory, so the CPU can fetch each instruction in turn and execute it.
Why: Linked point (1) and reason (1).
The instructions of the program are stored in main memory.
Why: Point only (1); no linked reason about fetching/executing the instructions.
The program is stored on the hard disk and is copied into the CPU when it is run.
Why: Misconception covered by the 'Do not accept' line: the instructions must be stored in main memory/RAM, not on the hard disk/backing store, for the CPU to fetch them.