Re: XP 32 bit Memory
- From: John Callaway <jcalla@xxxxxxxxx>
- Date: Sun, 06 Dec 2009 09:42:58 -0500
On Mon, 07 Dec 2009 08:34:33 -0400, John John - MVP
<audetweld@xxxxxxxxxxx> wrote:
J. P. Gilliver (John) wrote:
In message <883lh59rsnph5s2g2l2lsrbuua3jbui583@xxxxxxx>, "Ken Blake,
MVP" <kblake@xxxxxxxxxxxxxxxxxxxxxxxxx> writes:
[]
All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB[]
address space (64-bit versions can use much more). That's the
theoretical upper limit beyond which you can not go.
But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.
Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.
Since the hardware presumably doesn't need much, presumably the RAM
_beyond_ the hardware address _could_ be used, if someone were to write
a suitable "memory manager" (as used to be done in the early days of DOS
to get round the "640k" limit (and even a little around 1M, IIRR).
Unless the hardware uses incomplete address decoding, that is.
If such a manager were to be written, of course, only software that knew
about it could use it (like DOS software that either knew about being
"loaded high" or didn't), so there probably would be insufficient
usefulness for it to be worth anybody's while, since software houses
would be unlikely to cater for it.
That won't happen on NT operating systems, the kernel will simply not
allow it.
John
Ken Blake,
I do appreciate all the info on this matter. I recently
purchased a Dell laptop with W7 OS. I could not install some older
programs on it, so I tried to install XP 32 bit OS on a partition
that I resized with W7. The CD/DVD drive would not fully load the
install disc. I returned the computer. I have since done some research
and found out that if I have XP 32 Bit OS on the computer and then
load W 7 on it, it seems to go better. So I intend to buy another Dell
with W 7 OS, then resize the partition, making room for XP 32 bit OS
on the other partition. I will then Ghost the W 7 partition using
Norton. I will then load XP 32 bit OS over the W 7 OS providing the
CD/DVD will read the XP install disc. Then Ghost the W 7 OS on the
other partition. I have downloaded EasyBC boot loader utility to have
the option to dual boot to which OS I want on boot up.
Ken, am I on the right track?
John P. Callaway
.
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