[DUG] to Vista 64bit or not?

[Jolyon Smith]

No - the problem isn't a question of OS "features", so much as a simple
characteristic of 32-bitness.

 

In your system there are (in simple terms) two  kinds of memory:  system
(motherboard) memory and device memory.  That memory (again, hugely
simplified) becomes one big coalesced pool of RAM, and with 32-bit
addressing that pool cannot be more than 4GB (the address limit of a 32-bit
pointer).

 

So, if you have 4GB of RAM installed your CPU could not address the memory
in your graphics card, for example (let's say you have 512MB of GFX RAM, so
a simplified total of 4.5GB - that 0.5 GB can't be reached).

 

So, in a 32-bit system, a portion of the 32-bit address range is allocated
to the video card, meaning that an equally sized "window" of memory is no
longer addressable in your motherboard installed RAM.

 

So 0.5 GB of your address range is set aside for access to the GFX memory,
meaning that the addressable system memory is 4GB less the 0.5GB "window"
used to access the GFX RAM, i.e. system memory appears to be only 3.5GB

 

And bear in mind your graphics card isn't the only device with RAM that has
to be mapped into that 4GB range.

 

In a 64-bit system the address range is much wider so that video card RAM
can simply be addressed "on  top" of the system RAM, hence you get access to
ALL your system RAM no matter how much device memory is also in your system.

 

 

From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Jeremy Coulter
Sent: Friday, 7 August 2009 10:29
To: 'NZ Borland Developers Group - Delphi List'
Subject: Re: [DUG] to Vista 64bit or not?

 

does windows 7 see all the RAM?

 

Jeremy

 

  _____  

From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Jolyon Smith
Sent: 7 August 2009 10:27
To: 'NZ Borland Developers Group - Delphi List'
Subject: Re: [DUG] to Vista 64bit or not?

The real question though is how much benefit you actually got from that
extra 0.5 - 1GB ?

 

I'm guessing not much.  Not really.  But if you've got a system equipped
with 6GB or 8GB. at that point 64-bit makes perfect sense (and if you're the
sort of user that is loading a 4GB system so heavily that the extra 0.5-1GB
*does* make a difference, you're probably the sort of user that would like
6-8GB of RAM anyway and you've already long since moved on to 64-bit).

 

But at 4GB I really don't think there's much in it, so whilst there may not
be a specific reason to use 32-bit, there's also no great compelling reason
to use 64-bit either, and a few *potential* reasons not to (lack of 64-bit
support for XYZ, where XYZ varies from individual to individual) potential
complications when running (some) 32-bit software etc etc.

 

+0.02

 

From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Sean Cross
Sent: Friday, 7 August 2009 10:12
To: NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] to Vista 64bit or not?

 

Vista 32 will never see all 4 gb due to mapping issues with the video card
etc.  Under Vista 32, I got between 3 and 3.5 gb available on my laptops.
Vista 64 got the lot.  How much you lose depends on your video card memory.

 

Regards

 

Sean Cross
CIO

Catalyst Risk Management

 

From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Jolyon Smith
Sent: Friday, 7 August 2009 10:01 a.m.
To: 'NZ Borland Developers Group - Delphi List'
Subject: Re: [DUG] to Vista 64bit or not?

 

aiui if you've only got 4GB of RAM then I don't think 64-bit is going to
make that much of a difference.  Of course, if you have the capacity to go
beyond 4GB of physical RAM and the intention to do so, then 64-bit might be
worthwhile.

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listserver.123.net.nz/pipermail/delphi/attachments/20090807/87b2aeb0/attachment-0001.html