This is an excellent post describing the memory hierarchy in current PC architectures. It’s been a long time since I went to computer school, but I remember this being oversimplified even then. Nowadays, are students taught the horrible consequences of a cache miss? Or does one have to find it out for oneself?
Reading from L1 cache is like grabbing a piece of paper from your desk (3 seconds), L2 cache is picking up a book from a nearby shelf (14 seconds), and main system memory is taking a 4-minute walk down the hall to buy a Twix bar…waiting for a hard drive seek is like leaving the building to roam the earth for one year and three months.