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Originally Posted by jav1856
Like I said before, from what I have read I have come to the conclusion that the current Core Duo processor outperforms the Turion 64 X2 Mobile processor by a noticeable amount, and I agree with you that the Turion X2 Mobile is better than the Turion processor offered in the dv5000z. In my opinion there’s no reason to buy a notebook with an AMD processor unless you run 64 bit programs, other than Windows XP 64.
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Dude, you have to realize that there are a host of people who will get a great deal of performance increases from scientific applications. And Win XP 64 is certainly not the only x86_64 compatible. Most people who actually have a use for the wider datapath, 64 bit GPR, and large address space are using some distribution of linux.
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Originally Posted by jav1865
A 64 bit processor isn’t going to run a 32 bit application better than a 32 bit processor, unless you can load it up with ram. A 32 bit processor can address 4GB of ram, while a 64 bit processor can address 16 exabytes,
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No, 64 bit processor does not automatically address more than 4 GB RAM running a 32 bit OS environment. 64 bit is the width of the internal datapath in certain execution units in the CPU, as well as the size of the GPRs in the register file. Certain 32 bit OS can even allow for 36 bit addressing, by using bounce buffers supported by MMU with in the first 4GB of address space.
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Originally Posted by jav1856
so if you could add memory over the 4GB limit of a 32 bit processor you would get a real advantage from the 64 bit processor even on 32 bit applications.
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????
You do realize that it is the OS that manages the address space, right?
Windows in IA32 won't even allocate more than 2GB of space to any single application.
The size of the address space does NOT ONLY depend on the size of the GPRs, but also depend on the type of AGU, MMU, and the address bus from the memory controllers themselves. Current CPUs with x86_64 ISA allows for 40 bit physical space and 48 bit logical (virtual address space), which is much less than 64 bit address space. AMD's K8L will begin to allow 48 bit physical address and 1GB page, if I remember correctly, beginning next year.
And there is a chance in hell that any application running in an OS based on an IA32 compile is going to take advantage of more than 4GB of physical memory.
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Originally Posted by jav1865
There aren’t many notebooks with 4 memory slots, and those are the only ones capable of being upgraded with more than 4GB of memory, and to buy three 2GB memory sticks in a notebook is going to cost over $2300. On top of that I have read that XP only allows utilization of 3GB of ram because of security issues. Evidently XP doesn’t like a 1GB slot of unallocated memory; however this may not be the case with Windows XP 64.
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XP allows use of 2.5-3.75 GB of physical memory to be utilized by the OS because of the inherent limitation of devices that would need address space as well, particular any device on a peripheral interconnect. And these are mapped onto the end of the 32 bit space (ffff ffff). And the amount of lost space can vary from system to system.
And even with a 64 bit OS, you would still have the same problem, known in some circles as "memory hole" right before the 4GB limit. It is usually resolved by remapping the device addresses to higher than the size of the physical memory in the system, in those system that support either HW or SW remap.
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Originally Posted by jav1865
But that’s just my opinion of the Turion X2 Mobile, and I am not stuck to it and I could be wrong. I am looking to buy a new laptop in the next 3 weeks so if you could give me a reason or supply me with information on why I should buy and AMD Turion laptop over a Core Duo or Core 2 Duo version, I want to hear it so I don’t but the wrong thing.
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It doesn't seem that any of the previous assumptions you had is correct; And unlike what you assumed; 64 bit addressing is certainly not the only advantage of a 64 bit system; which when properly used, can speed up certain types of computations by a tremendous amount.
On top of that, you have to realize that certain features of Core uarchitecture is not supported when working in a 64 bit environment, such as macro-ops fusion. You will likely see a greater increase in performance from a Turion 64 X2 , going from a 32 bit OS to 64 bit OS; than you would see a C2D from 32 to 64. And on some applications, the increase in performance is substantial; and could even be a multiple fold increase going to 64 bit, if the type of computation requires a certain precision.
