New submitter DidgetMaster writes: Everyone knows that CPU registers are much faster than level1, level2, and level3 caches. Likewise, those caches are much faster than RAM; and RAM in turn is much faster than disk (even SSD). But the past 30 years have seen tremendous improvements in data access speeds at all these levels. RAM today is much, much faster than RAM 10, 20, or 30 years ago. Disk accesses are also tremendously faster than previously as steady improvements in hard drive technology and the even more impressive gains in flash memory have occurred. Is the 'gap' between the fastest RAM and the fastest disks bigger or smaller now than the gap was 10 or 20 years ago? Are the gaps between all the various levels getting bigger or smaller? Anyone know of a definitive source that tracks these gaps over time?