On Fri, 20 Jun 2008 20:43:34 -0400, Arne Vajhøj <arne@vajhoej.dk>
wrote, quoted or indirectly quoted someone who said :

>I assume you are trying to tell that the virtual address space
>is 9 million GB. Which is wrong. The potential max of virtual
>address space is 16 EB (16 billion GB)

Often you can't always use all 64 bits for addressing, but if you
did, that would give you addresses 0 .. 2^64-1
i..e 0.. 18,446,744,073,709,551,615

We have the problem of binary and decimal gigabytes. The article
http://mindprod.com/ggloss/sixtyfourbit.html is in the Buyer's
Glossary, not the Java glossary, so it is not aimed at programmers. I
thought it thus best to stick to decimal. It does not really matter.
The point I am trying to make is the addressing limit is well beyond
what you could afford in real ram.

A decimal gigabyte is 10^9, so that would make it the addressability
18,446,744 gb (twice the 9 million gb I used presuming the sign bit
bit of addressing would be chewed up by housekeeping.)

How did you get your number 16 billion GB. ? three orders of magnitude
bigger?

I presume the 16-18 difference comes from you using binary gigabytes.

To sort out the confusion, NIST has devised new prefixes when you mean
binary.
see http://physics.nist.gov/cuu/Units/binary.html
--

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com