@David09 - I guess I can see the advantage of direct mapping or any kind of cache technology if you are using a disk drive and want to store information in RAM.
However, I don't think that it matters if you were using flash memory. I have a small notebook that uses flash memory – there is no hard disk whatsoever.
In that case, I assume that all of the data read and write operations are already taking place in memory and therefore a separate cache would not be useful whatsoever.
That’s just my opinion; I can vouch that the flash memory is much faster than the hard disk from an older laptop.