S5-2.4 Memory Organization
You can explain the memory hierarchy, compare direct, associative and set-associative cache mapping, and describe virtual memory address translation using pages.
The memory hierarchy exists because fast memory is expensive and big memory is slow, and caching works only because real programs exhibit locality - without that empirical fact the whole edifice collapses. Practise the three mapping functions by translating the same address under each; the trade between hardware cost and conflict misses becomes obvious in a way prose cannot convey. Virtual memory is the same caching idea one level down, with disk backing RAM instead of RAM backing cache.
Work through these
Memory hierarchy
The pyramid that exists because fast memory is expensive and big memory is slow. Every item below is one level of it, so keep the picture in view.
Primary memory and auxiliary memory
The two ends of that pyramid and what each is actually made of. It grounds the abstraction before the caching items get going.
Associative memory
Memory addressed by what is in it rather than where it is. Unusual and expensive, and the mechanism behind the fully associative cache in the next items.
Cache memory
The level that makes the hierarchy work, and it only works because real programs return to the same data. Without that empirical fact the whole idea collapses, which is worth pausing on.
Mapping functions: direct, associative and set-associative
Practise by translating one address under all three schemes. The trade between hardware cost and conflict misses becomes obvious in a way that prose about it never manages.
Virtual memory: address mapping using pages
The same caching idea one level down, with disk standing behind main memory. Page tables are the bookkeeping, and seeing the parallel with the item above saves learning it twice.
Memory management
Who decides what lives where, and the policies that decide what gets evicted. It is where the hardware in this topic meets the operating system you will meet elsewhere.
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