Memory is used for many things, as I understand. It serves as a disk-cache, and contains the programs' instructions, and their stack & heap. Here's a thought experiment. If one doesn't care about the speed or time it takes for a computer to do the crunching, what is the bare minimum amount of memory one can have, assuming one has a very large disk? Is it possible to do away with memory, and just have a disk?
Disk-caching is obviously not required. If we set up swap space on the disk, program stack and heap also don't require memory. Is there anything that does require memory to be present?