Larry Maturo

The OS is not allocating the memory. Let me see if I can explain this.
In the old model, the processor at a RAM buss and an I/O buss, and
the OS could use all the RAM. In the new model, many devices
actually look like "RAM" to do OS. It reads a certain memory address
and it gets the value of some device, instead of memory, or it writes
to a certain memory address and it sets the value of some device.
The mother board manufacturer, and perhiperal manufactures all
have a hand in using memory for I/O. Since a 32 bit processor can only
access 4 gigs of RAM, if you put 4 gigs in, some of the address space
will be stolen by the memory mapped hardware. If you have a 64 bit
processor, there are plenty of memory addresses to go around, and
everyone is happy.

Note this is very simplified, and there is really no new model, as memory
addressed hardware has been around forever, but in the past, it was
rare to be able to get enough RAM for this to be a problem.

-- Larry Maturo


"Haydon" <me@privacy.net> wrote in message
news:V8adnbPS64InJMDbnZ2dneKdnZypnZ2d@pipex.net...
> Lets try again without spell-check defaulting to change!
>
> Hello Ken
>
> As you mentioned, 1GB is used for hardware. You also mentioned that
> installing more than 3GB of RAM is a waste of money.
>
> So, the question is, are there any benefits for Windows allocating 1GB of
> RAM for hardware? If not, why does it do it?
>
>
>>
>> "Ken Blake, MVP" <kblake@this.is.am.invalid.domain> wrote in message
>> news:tg9r53tl0fvqiothh8ij11n2deug5s7d5e@4ax.com...
>>>
>>> That is correct. 32-bit XP can use up to 4GB. However the 4GB address
>>> space has to be shared with memory used for other devices. So Windows
>>> (all 32-bit versions) can't use that entire 4GB for itself.
>>>
>>> How much it can use is around 3GB, but depends on what devices are
>>> installed. It's normally a little more than 3GB. So installing more
>>> than about 3GB of RAM is usually a waste of money.
>>>
>>