Am I semi Retarded?

[ReiaH]

So I bought 4gb of ram and a 32bit Vista with that, and I can only see 3,2 gb of that ram supported. So whats up with that, cause I recall that 32bit vista only supports 3,2gb ram..is that true? or am I semi retarded?

[caveman-jim]

32bit windows will only see 3-3.5gb of installed RAM because of ancient design limitations in the motherboard. Windows itself can see 4Gb, or more depending on version and supporting hardware.

Due to design decisions made by IBM (not Microsoft) the IBM PC could only use 640 kilobytes of its 1 megabyte memory map to address main memory. The rest was taken up with video memory, BIOS ROM, and various devices. So a full 37.5% of the memory map was out of bounds, imposing the infamous 640K limit on how much RAM you could fit, before having to resort to all sorts of hacks that never really worked very satisfactorily.

Then 32-bit systems came along. A few years later, 32-bit the mainstream OS market caught up. The 640K limit was relegated to a painful footnote in the history of the PC. (Yes, I know I just ignored about half a decade of the horrors of not-quite-32-bit operating systems, where the ghost of the 16-bit machine could still haunt you. But I for one ran Linux on the first PC I owned back in 1993, and then installed Windows NT in 1994 and haven't looked back, so I was able to avoid most of that carnage.)

To address 4GB of memory you need 32 bits of address bus. (Assuming individual bytes are addressable.) This gives us a problem - the same problem that IBM faced when designing the original PC. You tend to want to have more than just memory in a computer - you need things like graphics cards and hard disks to be accessible to the computer in order for it to be able to use them. So just as the original PC had to carve up the 8086's 1MB addressing range into memory (640K) and 'other' (384K), the same problem exists today if you want to fit memory and devices into a 32-bit address range: not all of the available 4GB of address space can be given over to memory.

This shouldn't be a problem. Contrary to popular belief, Intel's 32-bit CPUs have more than 32 address pins. They actually have 36, giving them the ability to address a 64GB physical address space. This means that you should in theory be able to fit 4GB of RAM, and still have plenty of space for memory mapped devices. In fact you can fit a whole lot more than 4GB.

Unfortunately it's not always so simple.

Historically, the PCI bus in most ordinary PCs has shared the same physical address space as the CPU. This means that if a device on the PCI bus looks at physical address 0x12345678, it will see exactly the same thing as the CPU would if it looked at the same physical address. It doesn't have to be this way of course - the CPU bus and the PCI bus are physically separate, and are connected by a bridging chip of some kind. This bridge could in theory perform some kind of mapping between addresses on the two buses. But for a long time, this didn't happen in PCs.

Windows NT/2000/XP/2003 has always supported mapping between PCI buses and the main system bus. This was necessary because back in the day when NT supported RISC systems, most of those did actually perform such a mapping. I used to write device drivers for DEC Alpha systems, and with those, the physical address the CPU used to access a particular bit of memory was usually different from the address used on the PCI bus. So if you write a device driver and wish to access a memory-mapped device, or get the device to perform some DMA, you are required to use system calls to find out what addresses the device will use on the PCI bus, and what physical address this corresponds to on the system bus. (Which will of course be different again from the virtual address of the memory in question.)

Presumably the reason PC architecture machines didn't do this is that this mapping layer increases costs, and makes it harder to achieve performance goals. So for years, the address map of the PCI bus and the address map of the system bus have been one and the same thing in the PC. (So the mapping APIs ended up passing you back the same address you passed in. Doubtless there are loads of device drivers out there that take advantage of this, omitting this call as an 'optimization'.) For a long time this wasn't a problem, because there was a whole 4GB of address space, so devices typically lurk up in the top 1GB of physical address space, leaving the bottom 3GB for memory.

So what actually happens if you go out and buy 4GB of memory for your PC? Well, it's just like the DOS days - there's a hole in your memory map for the IO. (Now it's only 25% of the total address space, but it's still a big hole.) So the bottom 3GB of your memory will be available, but there's an issue with that last 1GB.

If you're lucky, your PC will be able to do something clever. The usual solution is to make that last gigabyte appear further up in the memory map. So your memory's all still available, it just happens not to be contiguous. The first 3GB are present where you'd expect to find them, then there's a 1GB hole, reserved for devices, and the 4th GB of memory appears in the 5th GB of address space. So if you chose your motherboard wisely/flukily, all 4GB will be available to you.
How can you know which kind of motherboard to buy in order to avoid this? Right now it's not all that easy to tell actually, short of reading the datasheets for the chipset... If the mobo can take more than 4GB of memory, then you might be OK. Although they might just take the attitude of "If you can afford to fit 32GB of memory, you can afford for 1GB to go missing"...

In short, caveat emptor.

http://www.interact-sw.co.uk/iangblog/2005/08/05/is3gbenough

More info on Why you cant see all 4Gb on your machine

[caveman-jim]

Also, what's hinted at here but not explicitely stated, is that if you have a memory remap function in your motherboard's BIOS, you will need to use Physical Address Extensions (the /PAE switch for boot.ini) to be able to see and use the RAM added to the memory table, if that address range is above 4Gb.

[Lupine]

Yes. But what you're seeing is normal too.

[Sound_Card]

why 32bit may I ask?

[ReiaH]

I dont know..I asked the guy in the store what the difference between 64bit vista and 32 was..he said that 64bit was 3d..I Lol,d and bought the 32bit immiediatly.

[moshpit]

Ouch. My brain hurts...

[caveman-jim]

There's some pics in the linked blog, might help you out a bit

[night]

still retarded though

[moshpit]

No, the sales guy telling Reiah that the difference between 32bit and 64bit was 3D, that's what hurt my brain. I'd LOVE the phone number of the place that told him that. I'm not allowed to chew people up on the forums anymore, so calling that salesman and eating his lunch would just make my day

[Qb2k5]

Someone should make a sticky about this. This questions gets asked all the time.

Edit: nevermind

I guess Im going semi retarded.

[caveman-jim]

[ReiaH]

So the jurys out, I wasnt semi retarded after all.

[moshpit]

So the jurys out, I wasnt semi retarded after all.

No, just lied to by the salesman. You should go back in there and eat his lunch. I'd be all over that dummy.

[ultimadrift]

No, just lied to by the salesman. You should go back in there and eat his lunch. I'd be all over that dummy.

Its not polite to correct people

[moshpit]

Its not polite to correct people

I've never been an overly polite person. Polite is for pansies

[seeker010]

damn, foiled by rage3d members again. opened software is not eligible for refund

btw, doesn't microsoft allow you to order 64bit media if you've bought the 32bit version?

[moshpit]

damn, foiled by rage3d members again. opened software is not eligible for refund

btw, doesn't microsoft allow you to order 64bit media if you've bought the 32bit version?

Yes.

[caveman-jim]

Note one of the changes for Vista SP1:

With SP1, Windows Vista will report the amount of system memory installed rather than report the amount of system memory available to the OS. Therefore 32-bit systems equipped with 4GB of RAM will report all 4GB in many places throughout the OS, such as the System Control Panel. However, this behavior is dependent on having a compatible BIOS, so not all users may notice this change.

Notable Changes in Vista SP1

[Lupine]

Now Microsoft is going to get sued for 'misadvertising' the amount of memory available, joining ranks w/ monitor and hard drive mfgs.

[guest]

Now Microsoft is going to get sued for 'misadvertising' the amount of memory available, joining ranks w/ monitor and hard drive mfgs.

There never should have been a 32-bit version of Vista.

[Lupine]

There never should have been a 32-bit version of Vista.

QFT.

[-n7-]

QFT.

I agree, but...

MS doesn't really care about us.

They care about the mainstream market, who wouldn't have been ready for x64.

Now with RAM limitations forcing a switch to x64, it'll be interesting to see how they handle the transition in Windows 7.

[caveman-jim]

There had to be a 32bit version of Vista, given the lack of manufacturers developing good 64bit drivers before release, and the new driver model with signed driver enforcement. For Windows 7 I will be dissapointed if there is not a 64bit only push.

[Nazgul]

I agree, but...

MS doesn't really care about us.

They care about the mainstream market, who wouldn't have been ready for x64.

Now with RAM limitations forcing a switch to x64, it'll be interesting to see how they handle the transition in Windows 7.

I'd be very surprised if there was a 32-bit version of Windows 7.

[-n7-]

I'd be very surprised if there was a 32-bit version of Windows 7.

Then you'll be surprised.

There will be some form of x86 version of Windows 7, mark this my words (or this post ).

I just hope they push x64 as the primary/good choice, & i think they will.

[compunoob]

This where researching before you buy is a good thing. I do not trust sales people as that is what they are doing selling. I will take the opinion and knowledge of users over that any day.

[Tizen]

Its not polite to correct people

Yes, I'm sure I'd like to be in the dark
FFS, not polite to correct people when they are wrong? What the bloody hell is that suppost to mean

[Tizen]

32bit needs to die... and fast

[caveman-jim]

Yes, I'm sure I'd like to be in the dark
FFS, not polite to correct people when they are wrong? What the bloody hell is that suppost to mean

I think you missed the joke on that one.

[moshpit]

Yes, I'm sure I'd like to be in the dark
FFS, not polite to correct people when they are wrong? What the bloody hell is that suppost to mean

LOL, yup, as caveman said, you missed the joke. No biggy

[SirBaron]

There had to be a 32bit version of Vista, given the lack of manufacturers developing good 64bit drivers before release, and the new driver model with signed driver enforcement. For Windows 7 I will be dissapointed if there is not a 64bit only push.

Yeah but had there not been a 32bit version, they would of had to make 64bit drivers otherwise they would of lost potential sales. Because some other companies would of made 64bit drivers... which would force them to.

Granted i have 32bit my self, but because my wireless device is crapgear, and has no 64bit drivers... that and i cant be arsed filling a order form for a 64bit DVD from microsoft.

They should allow direct dvd iso downloads ffs.

[Lupine]

There had to be a 32bit version of Vista, given the lack of manufacturers developing good 64bit drivers before release, and the new driver model with signed driver enforcement. For Windows 7 I will be dissapointed if there is not a 64bit only push.

Perhaps, but Microsoft did it backward. 64bit should have been the name of the game, w/ 32bit available on demand. Instead, quite often end users got 32bit by default and had to special order the x64 version. Furthermore, if Microsoft had chosen to push Vista as x64 as the primary version, there was plenty of time during the development process to make mfgs aware of this, motivating them to get their drivers prepped for the launch.

[caveman-jim]

Easy to say, hard to do. Microsoft did the safe choice, and given how contraversial Vista still is (lots of FUD about it being bloated, unusable where XP is perfect, application and game incompatibilities) they made the right choice.

For Windows 7 a lot of the technical reasons go away - higher powered base machines, dual core cheaper than gasoline, RAM free with a packet of cornflakes, new windows driver model and kernel access modes well established - all in all, could add up to the success of a 64bit primary platform.

However, I think the future of the OS is going to be hypervisor based, where the core is 64bit and 32bit or 64bit guest para-VM's run the applications. This could lead to a marked increase in the security and stablilty of the host OS, and of applications. Think MAC OS X running vmware fusion, but with two (or more) MS OS's seamlessly integrated - 32bit for legacy applications, 64bit for newer. Would be heavier on RAM, and disk space, effectively running two installs concurrently, but the potential there is high, especially is a secure manner for accessing storage and peripherals is implemented.

[Nazgul]

Perhaps, but Microsoft did it backward. 64bit should have been the name of the game, w/ 32bit available on demand. Instead, quite often end users got 32bit by default and had to special order the x64 version. Furthermore, if Microsoft had chosen to push Vista as x64 as the primary version, there was plenty of time during the development process to make mfgs aware of this, motivating them to get their drivers prepped for the launch.

The default was 32-bit so folks wouldn't be hit with compatibility problems right out of the gate. And let's be honest, most of the folks who wouldn't have paid attention to 32 vs 64 bit when they got it probably wouldn't have benefited from 64-bit anyway.

[Gator]

Sorry to bump an old thread, but can someone tell me if Windows 2003 32-bit suffers from this issue as well?

I'm setting up another rig in a few days for hosting virtual machines, and I just want to know if I'm installing 3GB or 4GB of RAM. Sadly I do not have Windows 2003 x64 version.

[caveman-jim]

Standard does have the limitation, Enterprise does not. Depending on install hardware you'll see between 3.25 ~ 3.75Gb; maybe 2.75Gb in worse case. Populate it with 4Gb unless you have a pressing need for the extra RAM elsewhere.

Windows Server 2003 Standard Edition: 4 GB
Windows Server 2003 Enterprise Edition: 32 GB
Windows Server 2003 Datacenter Edition: 64 GB

http://support.microsoft.com/kb/555223

[Crisler]

You know what I am wondering why the crap then we cannot make a 32 bit desktop OS to access more than 4 gig when they do it with server software?

[caveman-jim]

Because Microsoft have invested considerable resources and time into making a 32bit kernel that supports more than 4Gb of system RAM (note that this does not increase the amount of RAM a single process (or the OS) can use unless specially coded and handled for that environment). This goes into the realm of diminshing returns - it's only now in 2007/2008 that mass market applications (i.e. games) are running into the limits of available RAM addressable by 32bit standard kernels, and the best solution is to move to 64-bit (increased security through kernel design, faster memory access through greater bandwidth [64bit chunks instead of 32] and no performance hit from software page address extension).

[metroidfox]

Quick question about ordering the x64 version of Vista: does this apply to OEM versions as well (i.e. with the copy of Home Premium I received with my Inspiron)?