32bit OS and Memory

**Imisnew2** · 03-09-10, 06:34 PM

I know this much... that 32bit means there are 4Gig addresses... So why can a 32 bit OS only have 3 GB?
Is it because the mobo maps the other 1G of addresses to other things? (Video card, Bios, etc?)

Like there are only enough address lines to support 4Gig addresses?

I assume 64bit OS's just send the "top half" of the address and the "bottom half" of the address to get 64bit?

Idk.. that's why I'm asking you all.

**Sgt.TmH** · 03-09-10, 06:43 PM

Originally Posted by Imisnew2

I know this much... that 32bit means there are 4Gig addresses... So why can a 32 bit OS only have 3 GB?
Is it because the mobo maps the other 1G of addresses to other things? (Video card, Bios, etc?)

Like there are only enough address lines to support 4Gig addresses?

I assume 64bit OS's just send the "top half" of the address and the "bottom half" of the address to get 64bit?

Idk.. that's why I'm asking you all.

Google is a wonderful thing - http://www.google.com/search?hl=en&q...es+XP+only+rec

The quick answer is what you guessed - the other memory space is allocated for other uses besides System Memory.