Is it possible through ASM to sequencialy load each byte of memory from range X to X into a file on a HardDisk? Be very useful on critical projects. Could then link to a shortcut save and load keys ont he keyboard.

why, this is usualy done. Just open file, write the N bytes from position X to hdd and close file handle. Or did you meant it without using OS? THne you have to have some hdd driver

It isn't just that easy
99% of memory addresses give errors even when NOT writing to them. I'm using Win2000 and when I tried to copy &200000-&200400 or about 1KB to dat.txt, then my program ran tgether and DrWatson said that memory was accessed illegally.
I have 256MB of RAM so the values should be legal, but I have tried starting from 1 and I wasn't lucky even in &FFFFFFF

of course, protected mode, you can only access memory allocated for your process. You can't modify or even read memory of other processes (so easily).

i found this on daily rotation.

It's written in MASM. I can live with that, but why does it use so much calls???
I have seen programs capable of saving few megs per second. With this I got ~128KB/s. The calls take clocks!!!