Maximum RAM on 64-bit
in [Windows XP]
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From: dennis on 5 Jun 2010 07:16 On 05-06-2010 02:32, Paul wrote: > If the processor is set up to use 36 bit addresses (i.e. PAE), > then those locations could be accessed. They'd no longer be > inaccessible, due to a decoding limitation. Even PAE cannot solve it alone. Memory locations must be remapped. The overlap between MMIO and DRAM is usually solved by moving the overlapped DRAM up above 4G. PAE can then be used to get to it.
From: Bob I on 7 Jun 2010 10:45 Stefan Patric wrote: > On Fri, 04 Jun 2010 08:01:38 -0500, Bob I wrote: > > >>Stefan Patric wrote: >> >>>On Thu, 03 Jun 2010 07:39:24 -0500, Bob I wrote: >>> >>> >>> >>>>Stefan Patric wrote: >>>> >>>> >>>> >>>>>On Wed, 02 Jun 2010 13:51:37 -0500, Bob I wrote: >>>>> >>>>> >>>>> >>>>> >>>>>>128 GB on XP-64 but 32-bit has 4 GB of address space, not 3. >>>>> >>>>> >>>>>Technically, yes. But only about 3.2 is available to the user. The >>>>>balance is reserved exclusively for the System. >>>>> >>>>> >>>>> >>>> >>>>The variable amount of unused RAM is entirely dependant on the >>>>particular hardware installed on the particular computer. The OP stated >>>>that 3 GB was the limit and that is incorrect. As to 3.2 GB, once again >>>>that is NOT a limit, nor is it "reserved", it is used to comunicate >>>>with installed hardware. Remove or reconfigure hardware and the value >>>>will change. All you can say is that 3.2 GB is an approximate value for >>>>common pc configurations. >>> >>> >>>And that is why I said "about 3.2" meaning not exactly 3.2, but around >>>3.2 or approximately 3.2. Even on a system with the barest of >>>hardware, I myself have never seen more than about 3.35 available. >>>Although, I've read claims of 3.5. >>> >>>Also, what would you call RAM that is exclusively accessible ONLY by >>>the system for its use, that is, users or their apps can't access it? >>>To me, that is the very definition of "reserved." >>> >>> >> >>I've seen anywhere from 2.7 to 3.7 available out of 4 GB. and it is the >> memory addresses that are being used not the memory itself. Give it >>up, you're clutching at straws. > > > Based on Paul's explanation making a distinction between "reserved" and > "inaccessible," it seems the word "reserved" has special meaning to those > who's vocation are computers other than how it is general used. > Have you ever seen a "Reserved" Sign? It means "set aside" just in case something "might need it". Memory addresses are assigned to hardware, they are being used, not "reserved", whether that hardware is a video card, USB port or RAM. Everybody just seems to get into a regular tizzy about the RAM assignments though.
From: dennis on 7 Jun 2010 12:50 On 07-06-2010 16:45, Bob I wrote: > Have you ever seen a "Reserved" Sign? It means "set aside" just in case > something "might need it". Memory addresses are assigned to hardware, > they are being used, not "reserved", whether that hardware is a video > card, USB port or RAM. Everybody just seems to get into a regular tizzy > about the RAM assignments though. > > It really depends on how you use the word "reserved" and in what context. To say that a part of the address space is reserved for other use than DRAM is very valid.
From: Bob I on 7 Jun 2010 15:43
dennis wrote: > On 07-06-2010 16:45, Bob I wrote: > >> Have you ever seen a "Reserved" Sign? It means "set aside" just in case >> something "might need it". Memory addresses are assigned to hardware, >> they are being used, not "reserved", whether that hardware is a video >> card, USB port or RAM. Everybody just seems to get into a regular tizzy >> about the RAM assignments though. >> >> > > It really depends on how you use the word "reserved" and in what context. > > To say that a part of the address space is reserved for other use than > DRAM is very valid. Since those addresses aare already in use addressing the hardware, it is somewhat difficult to say they are "reserved" for other use? |