Use All the Memory You are Entitled to Have on Windows

[alexander]

Yes, you are probably sitting there, confused, thinking "Huh, what in the world does he mean?"

Well, let me clear some fog for you, so you understand what i am talking about.

But first, a history lesson

Back in time, when Windows 3.0 came out, people thought they wanted a bit more out of their memory. It supported 16 megs, but some people wanted more, much more, so Microsoft came up with a work around, an XMS driver that replaced Highmem DOS module and enabled addressing up from 16 megs of ram, and as reported, up to 512 megs... (astronomical values at the time)

Soon Microsoft did away with the 8096k bit descriptors and 64K possible combinations (which bring the theoretical limit of such a system to 512mb (multiply the two))

Fast forward to today's world of XP and Vista (and Standard Server Editions) memory support has been greatly improved. We are now reaching the theoretical maxims of the 32 bit processors, which can not use more then 4GB of ram, by design. (2 bits 32 registers equates to 2^32 or 4GB)
64 bit processors are in the petabyte ranges, 128 bit processors limits are so astronomical, doubt there is enough silicon to fill it for now anyways. ()

Anyhow, there have been methods devised that allow one to access more then the hardware limit of memory and we have discussed those here at some point, if you are still wodnering, just Google for highmem.

Anyways, so what i have come to find is that windows memory drivers, by default, do not allow you to have access to full 4GB, and no process can take up more then 2GB of Ram (i think microsoft is limiting itself there) and the system, can only access 3.5GB of memory (no matter what it tells you). Luckily they have created Physical Address Extension (PAE), and even though on most systems it does not increase support of signifficant amount of memory, it alows you to use the memory you already have, to its fullest (assuming i'm not the only person who has multiple systems pushing the limits)

Enabling PAE is pretty straight forward:
Edit the boot up line in C:\boot.ini and add /PAE to the line

ex:

Before
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windo ws Server 2003, Standard" /noexecute=optout /fastdetect

After
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windo ws Server 2003, Standard" /noexecute=optout /fastdetect /PAE

This enables you to use:
4Gb windows xp
4Gb windows vista
4Gb windows server 2003 standard
4Gb windows server 2008 standard
64Gb on enterprise and datacenter editions for both 2003 and 2008
8GB on 2000 advanced server
and 32Gb on 2000 datacenter edition

Enjoy :| err, well, whatever

[Boerseun]

...and change the /noexecute=optout to /noexecute=alwaysoff while you're at it. Gratuitous system crashes and freezes down by 99%!

Thanks for the info, btw. On a 4Gb RAM box, why would Windows limit itself to 3.5Gb? If that's bad design, and it can be cleared with a single boot.ini switch, why would current-edition vanilla installs still default to the previous state? Why not make the /PAE switch the default, with currently-shipping versions of Windoze?

Am I just dumb, or am I missing something here?

[Donk]

Originally Posted by alexander

Enabling PAE is pretty straight forward:
Edit the boot up line in C:\boot.ini and add \PAE to the line

...

After
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windo ws Server 2003, Standard" /noexecute=optout /fastdetect /PAE

\PAE or /PAE ?
Or doesn't it make a difference?

[Buffy]

Windows flags are always forward-slash, so in this case /PAE is correct.

Yes, it matters a lot!

Keyboard work creates a class of unwanted things - one-letter typos, failures of phrasing, bad punctuation. If you don't want to delete these entirely, you can use the Return key to push them to the bottom of the screen,
Buffy

[alexander]

oooops typo there, i fixed it, ofcourse it is /PAE

Originally Posted by Boerseun

Why not make the /PAE switch the default

because the problem is that they like to not have to create virtual memory tables, as it complicates the kernel a little bit.... and also there is no need for the PAE support for MOST, meaning 98% of Windows users... (hope that answers that)

[Boerseun]

Won't a Windoze machine running 4Gb with virtual memory tables adressing the initial missing 0.5Gb run a tad slower than the same machine using the default 3.5Gb with all the memory tables in RAM?

[alexander]

not that noticeably