Going from 16 bit to 32 bit increased addressable memory by not by 2, but by 65.000. Not bad, however 64 for bit is not twice as much as 32 bit either.. its <b>4 billion</b> times as much..
Let's just focus on memory addressing to get an idea of what we are talking about. Assume 1 GB Dimms are 5mm thick.
*) A 32 bit machine can address 4 of those, put them on a pile, and you get 2cm.
*) PAE allows 36 bit addressing, that gives you 64 GByte, 32 cm or a pile as high as a few good books.
*) Opteron (and I think Itanium) allow up to 40 bit physical addressing. That is one terrabyte, or the equivalent of over half a meter of 1 GB Dimms per cpu. Not very practical yet.
*) Opteron and Itanium allow 48 bit virtual memory addressing, 48 bit represents 256 terrabyte, or a tower off 131 meter of 1 GB dimms. should be enough for a while
*) If you'd fully exploit the 64 bit addressing that means 16 million terrabyte, or a pile off well over 8000 kilometer high !! most satellite orbit below 1000 km. See how ridiculous 64 bit addressing is already ? 32 bit doesnt always cut it anymore, but 64 bit is MASSIVE overkill.
*) Now, you are suggesting 128 bit. that allows 309.485.009.821.345.000.000.000.000 terrabyte addressing. Even using hypothetical terrabyte DIMMS, that is a pile of 16 million LIGHTYEARS (roughly 154.742.504.910.673.000.000,00 kilometer).
You see.. there are 10 kind of people; those that understand binary, and those that don't
= The views stated herein are my personal views, and not necessarily the views of my wife. =<P ID="edit"><FONT SIZE=-1><EM>Edited by bbaeyens on 09/29/03 06:20 AM.</EM></FONT></P>