Chaszmyr said:
I don't know how the calculations work, but a 32 bit chip can address 4gb of RAM, and the G5 (a 64 bit chip) can address 4tb of RAM, so I am assuming a 128 bit chip may be able to address 4pb of RAM. (I wouldn't be even a little bit surprised if this is wrong, I'm too lazy to find out for sure, but I assure you a 128 bit chip can address a huge amount of RAM).
Huge is right!
A 1-bit machine can address two bytes: the one called 0 and the one called 1.
A 2-bit machine can address four (2*2) bytes: 00, 01, 10, and 11.
A 3-bit machine can address eight (2*2*2) bytes: 000, 001, 010, 011, 100, 101, 110, 111.
A 4-bit machine can address sixteen = 2^4 = 2*2*2*2 bytes.
Similarly, a 32-bit machine can address 2^32 = 2*2*2*...*2 (32 of them) bytes. That's 4 GB, about 4 billion.
A 64-bit machine can address 2^64 bytes. That's about 18 exabytes. 18 followed by 18 zeros. 18446744073709551616 to be precise. That's huge.
Now, a 128-bit machine -- of course, you can extend the pattern. Is it going to be twice as much as a 64-bit machine? How about four times? Eight? A billion times? No, actually, it's 2^64 times more than 2^64.
Here's the number:
340282366920938463463374607431768211456
I'm not even going to try to find SI prefixes for that. It's nuts.
So, no, there is absolutely no point for consumer machines to address more than 64 bits of address space at this point in time. We're not quite in the territory of "number of atoms in the universe" but we're definitely blasting off our home planet before we are looking at 128-bit machines making any sense in your personal computer.
Hope that helps clear it up!