I will soon be teaching a lesson on ROM, RAM, and virtual memory.
The problem is with “virtual memory”:
Some of the teaching resources correctly use the phrase virtual memory, and physical memory, and describe how virtual is mapped to physical via the memory management unit.
The computer's operating system, using a combination of hardware and software, maps memory addresses used by a program, called virtual addresses, into physical addresses in computer memory. Main storage, as seen by a process or task, appears as a contiguous address space or collection of contiguous segments. The operating system manages virtual address spaces and the assignment of real memory to virtual memory. Address translation hardware in the CPU, often referred to as a memory management unit or MMU, automatically translates virtual addresses to physical addresses. Software within the operating system may extend these capabilities to provide a virtual address space that can exceed the capacity of real memory and thus reference more memory than is physically present in the computer.
While in other resources they use the phrase “virtual memory”, and describe “paging”.
Virtual memory is a section of volatile memory created temporarily on the storage drive. It is created when a computer is running many processes at once and RAM is running low.
The operating system makes part of the storage drive available to use as RAM. Virtual memory is much slower than main memory because processing power is being taken up by moving data around, rather than just executing instructions. The guide on operating systems explains how the OS manages memory.
Taken from https://www.bbc.co.uk/education/guides/zmb9mp3/revision/8 Though I have seen the same in resources approved by the exam board.
So the question is what do I do in these situations?
- The exam board is wrong, but clear about what they think the answer is.
- The exam board is unclear about the answer.
UK England, GCSE / A-Level