64-Bit Addressing - See what I mean?

"If you want to make use of 4GB, you'll need a 64-bit OS."

This is a real quote from this board AND it's incorrect.

32-bits will address 4 gigabytes of memory-period. The exec is involved also but users frequently forget the exec. It can't be omitted.

Renee

 

so i dont need a 64 bit os to use more then 4 gig of ram ?

 

In a way, yes, and in a way, no. For you to see the memory usage (in Task Manager, for example) and for your programs to utilize the full 4GB, you will need a 64-bit OS.

But, if you have a 32-bit OS, it can still use the "unseen" part of the RAM for the OS exec - your programs, however, will not utilize this area of RAM (which could be an issue in, for example, intensive gaming or calculation programs that need a lot of RAM).

Renee, you certainly do make a good point, and it's nice to provide some clarification on the matter

 

so the unseen part is used as a swap ?

 

Okay, but in practice why is it that people seem to only be able to access around 3GB out of the 4GB installed?

Does the following come into play?

" the maximum memory available in 32-bit versions of Windows Vista is typically 3.12 GB" -- source http://support.microsoft.com/kb/929605

 

Ummm. 32 bit addressing will give you EXACTLY 4GB of addresses. Since other hardware will ALWAYS use address space, no matter how little it is (and it's usually not little, lots of people show 3GB/4GB in their 32 bit OS), you'll never fully utilize all 4GB of memory.
This is leaving out PAE, which not only isn't compatible with all systems nor all software, also gives a performance depredation.
The only real effective way to utilize 4GB or more of RAM is to use a 64 bit operating system.

 

32bit translates to 4GB of memory, yes. But RAM isn't the only memory in a computer. Memory also includes video memory from video card as well. That's why not all 4GB of RAM is usable.

 

If you want to make use of ALL 4GB of RAM, you'll need a 64-bit OS, period.

Then again, ~3.5 GB of RAM will work for most people too—and a 32-bit OS will do this amount just fine.

The BIOS and other hardware need to be addressed as well and they use a portion of the 32-bit address space for this—and, as a result, this portion of RAM is inaccessible. Welcome to the aging x86 architecture.

What’s the fix? Use a 64-bit OS. With RAM being so cheap, 64-bit will become mainstream soon enough anyway.

Of course, this excludes PAE.

 

One question at a time. "But RAM isn't the only memory in a computer. Memory also includes video memory from video card as well. That's why not all 4GB of RAM is usable."

That ram... is addressed by the controller in the card so it doesn't count as addressable memory to the computer ....just the card. Ram that is shared by both counts against non-pagedpool and therefore against the 4 gigabytes. If it's addressable by the cpu then it counts aginst the 4 gigs.

-Renee

 

'If you want to make use of ALL 4GB of RAM, you'll need a 64-bit OS, period."

Here's the error again in this thread BUT this time let's take a look at it.

"All 4 GB of RAM" is undefined. Is there more? And what about the exec? It takes memory too. Still there is a principle, 4 gigabytes equals 32 bits. Since the exec takes space (including non-paged pool for drivers) thats 4 gigs total. If there is more than about 3.5 gigs of user space (non-exec space), then that space or all the space for that computer is 64 bits because 32 bits of addressability has been exceeded.

They didn't used to show full addressibility INCLUDING the exec. They are beginning to now.

-Renee

 

"Ummm. 32 bit addressing will give you EXACTLY 4GB of addresses. Since other hardware will ALWAYS use address space, no matter how little it is (and it's usually not little, lots of people show 3GB/4GB in their 32 bit OS), you'll never fully utilize all 4GB of memory."

Hep, your right and wrong. Your right about the 32 bits. But of the people who show 3-4 gigs, you have to specify the OS and the the task which you did neither because Microsoft has changed the way they are displaying in Windows 7 and maybe Vista. I run Vista here on my system at the hospital and I'll be happy to run a Vista test for anyone. I know I'm running a Vista 64 bit system and I'm runing, I think, 4 gigs on this Extreme.

Renee

 

Why try to pick a fight about this? For all intents and purposes, yes you do need a 64 bit OS. Simple as that.

 

I don't even understand what you're saying. You're running Vista X64 and you're able to use all 4GB? Congrats, you're average.
My post wasn't right and wrong, no matter what OS, no matter who makes it - I don't care if it's Ubuntu, or OS 9, or Windows 2000, XP, ME, Vista, Win7... I don't care. ANY 32 bit OS, BY THE NATURE OF THE 32 BIT ADDRESSING SCHEME CAN ONLY SEE A TOTAL OF 4GB OF ADDRESSES.

Maybe I'm misunderstanding you... are you saying that no one needs 4GB of RAM? Please, clarify.

 

You’re making a mountain out of a molehill—or are just confused.

To try to make things simple, you have 2 to the 32 power of bytes of memory to address in a 32-bit environment—so 4294967296 bytes (4GB)/addresses. Since, for example, the BIOS can only be addressed via memory addresses, it might use memory address 1 through 1024000 for itself—and, as a result, this section of memory is no longer accessible to the operating system. The BIOS has reserved it and the OS cannot use it. There is now only 4293943296 bytes/addresses left. Other hardware will reserve address space as well and prevent the OS from using it too.

On the other hand, you have 2 to the 64 power of bytes of memory to address in a 64-bit environment (in theory)—so 18446744073709551616 bytes (16EB)/addresses. If the BIOS chooses to use memory address 1 through 1024000 for itself, that’s perfectly fine—the OS will still be able to address the entire 4GB on top of this since we will not be hitting the limits of a 64-bit address space anytime soon.

Almost anything to the contrary of this, including magic exec space, is mental mast*rbation.

 

Up to 256MB of address space is allocated per video card, and is lost from the rest of the system's address space.

 

It depends on who is doing the addressing in the videocard HEP, if its "the system" I've covered it. If it's just the card I've covered it.

Renee

 

I am always willing to learn when I am wrong.
Please show me some documentation on what you are specifically talking about.

So, how much memory can you use on a 32 bit OS?

 

4 gigs. Thats what I've always maintained. As for credentails, how will 30 years with Digital Equipment Corporation do in a software position all the time? Digital put the VAX, the first 32 bit machine out. That was our main machine for 30 years. VMS Engineering came after me for something I invented in the field that became part of the OS. I do not need any credentials to say that 32 bits = 4 gigabytes in a virtual machine where the machine is byte adressable. A lot of people have written that here.

Renee

 

From Toms Hardware

"There are a few items that need to be mentioned, as 64-bit systems do in fact have several advantages that go beyond the issues of processing and addressing. First, a 32-bit version of Windows is limited to a maximum of 4 GB RAM, and so will not give you the full memory for your applications—operating system processes are mapped into the address space, resulting in an effective memory capacity of 3 GB, or sometimes a bit more. Effectively, the maximum (User memory - My change - Renee) memory capacity is limited to only 3+ GB. A 64-bit version of Windows will give you access to more available memory as you add it."

Renee

 

Thanks for proving the point of everyone else in this thread. No one is saying 32 bits doesn't equal 4GB of addresses. We're saying exactly that - that 4GB addresses minus BIOS shadowing, VRAM mapping, other hardware = under 4GB of usable system memory.

 

thank god this is hopefully over =P

 

Nope. As long as people are posting errors it'll continue.

 

But you just proved yourself wrong ?

 

"We're saying exactly that - that 4GB addresses minus BIOS shadowing, VRAM mapping, other hardware = under 4GB of usable system memory."

I've been saying that 32 bits = 4gb in byte adresses. I don't care about the bios or whatever because it's treated as a system virtual address. That's not incorrect, that's physics.

I've been careful in what I've said. I invite you, or anyone else to find an error in what I've said. If you think you have, put the quote here and let's examine it fully.

The statement above is not correct. The memory is quite useable, it's course used by system (the exec + driver + nonpaged pool) and user space. Is there any here that thinks they don't use the exec? How do they do I/O then?

Renee

 

I have no doubt you have a lot of experience in your area of expertise, but you might want to spend some time reading up on non-VAX architectures—particularly the x86 and x86-64 architectures that most of us use in our notebooks. Not everyone here is a systems engineer and all they want to know is how get Windows to expose the 4GB of RAM they just purchased

I look forward to your retractions after you’ve read up on the x86 architecture and wrapped your head around current implementations of BIOS, PCI and other forms of memory-mapped I/O (MMIO).

 

There will not be any retractions because 32 bits = 4 gigabytes on a byte addressable machine.

As far as the Windows architecture is concerned its either a 32 or 64 bit machine. In fact, Dave Cutler did Windows NT as Chief Engineer and Dave originally did VMS. So there was lots of cross fertilization because they both started as 32 bit OS's. Lou Perrazoli is another DECie that went to Microsoft as Cutler's Executive chief. Lou came from the same office in DC that I did.

So I'll be looking for your apologies although the dynamics would surprise me if you apologized. Oh and by the way, I sucessfully interviewed with Dave out at Redmond in '86 as he was gearing up for a new project at 'DECWest'. Or Vince Orgovan, also from the DC office went to work for Microsoft.

A second "by the way" may be that I am currently a Microsoft MVP for the second year in a row. When I'm not here, I do Windows forums work which I've done since '04.

Renee

 

I sincerely hope you don’t spread this same misadvise on Windows forums and tell people the 4GB of RAM they just purchased will be fully useable in their 32-bit OS—contrary to MS’s own literature and noted by Lew at http://forum.notebookreview.com/showpost.php?p=5026162&postcount=5.

 

Alright before this devolves any further, let's just say we can disagree even vehemently while maintaining a friendly and productive atmosphere. If this thread erodes any more it will be closed as was the other 4GB of memory in XP thread.

 

So to simplify this for the average computer user, if I want to take fulladvantage of my 4gb of RAM, should I upgrade to a 64bit OS?

 

If all you use is 32-bit application, it won't even matter, since the most they can use is 3GB. But 64-bit applications are coming out (like Microsoft Office 2010, Matlab, Photoshop, etc...) that can fully utilize all your RAM.
I'm just gonna retreat, sit back, and relax, while the "expert" shows us "clueless masses" they truth. She is a Microsoft MVP, after all. We are not worth it, dear intelligent one.

 

This is exactly what I meant when I said if this thread erodes any further, it will closed. You couldn't even make it more than two posts?