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How can a Mac have up to 16 terabytes of system memory?
How can a Mac have up to 16 terabytes of system memory?
64-bit (http://en.wikipedia.org/wiki/64-bit)
Limitations
Most 64-bit microprocessors on the market today have an artificial limit on the amount of memory they can address, because physical constraints make it impossible to support the full 16.8 million terabyte capacity. For example, the AMD64 architecture has a 52-bit limit on physical memory and currently only supports a 48-bit virtual address space[1].
Theoretical amount of RAM a 64-bit machine can address is 16.8 million TB. So the restriction put in place by the OS is an artificial one.
layman's terms?
Swiff Reply
nvm. Im not understand a word you are saying either way
layman's terms?
Swiff Reply
nvm. Im not understand a word you are saying either way
OSX is 64-bit. 64-bit processors can address up to 16.8 million TB. The restriction in place (typically less than 64 GB) is a put in place artificially by the OS. Physical hardware limitations (currently) prevent any processor from addressing the full amount.
Mac controls its hardware. They made it so you can address up to 16TB of RAM.
six_storm
07-10-09, 04:07 PM
Can't wait to get my Macbook Pro w/Snow Leopard.
OSX is 64-bit. 64-bit processors can address up to 16.8 million TB. The restriction in place (typically less than 64 GB) is a put in place artificially by the OS. Physical hardware limitations (currently) prevent any processor from addressing the full amount.
Mac controls its hardware. They made it so you can address up to 16TB of RAM.
OOOOOOOOOOO
So Windows made it so that we can't have like over 64GB?
If windows wanted to, could it make it 16.8 TB?
LovingSticky
07-10-09, 05:07 PM
Already Windows Server 2003 (SP2) could address 2TB of RAM:
http://msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx
But this is purely theoretical limit, as NO current chipset can handle / address that much memory. Most desktop Intel chipsets end at 8/16/32 GB (only!). And this hardware limit applies to OS X as well, as it is same PC architecture as Dell and/or Acer.
Btw, Apple is really late to x64 market - Vista x64 was launched in 2006, with 64bit memory access, 64bit device drivers, and 64bit kernel. OS X Snow Leopard will "copy" this approach in desktop OS in 2009, ie. Apple is (at least) 3 years behind Microsoft.
Apple has been running with some support for 64-bit via OSX since at least 2003 afaik.
LovingSticky
07-10-09, 05:51 PM
No, most of OS X is still 32bit, including kernel, KEXTs, device drivers, etc., and access to RAM is done via PAE (very slow). Really obsolete architecture.
http://images.appleinsider.com/leopard-081028.gif
Already Windows XP x64 was truly 64bit, 4 years before Snow Leopard.. (I am speaking about desktop OSes here)
Oooh I like that image. Explains it much better to me. I heard that OSX's initial adoption of 64-bit was kind of half and half, now I see how it was heh.
nekrosoft13
07-11-09, 12:14 PM
wow 64bit chess ;)
Rakeesh
07-11-09, 12:50 PM
64-bit (http://en.wikipedia.org/wiki/64-bit)
Theoretical amount of RAM a 64-bit machine can address is 16.8 million TB. So the restriction put in place by the OS is an artificial one.
Or more simply, 16 exobytes.
2^64=18,446,744,073,709,551,616
Divide that by 2^60 which is exactly one exobyte, and you have 16 exobytes.
More fun with numbers for ya:
2^10 = 1 KB
2^20 = 1 MB
2^30 = 1 GB
2^40 = 1 TB
2^50 = 1 PB
Or more simply, 16 exobytes.
2^64=18,446,744,073,709,551,616
Divide that by 2^60 which is exactly one exobyte, and you have 16 exobytes.
More fun with numbers for ya:
2^10 = 1 KB
2^20 = 1 MB
2^30 = 1 GB
2^40 = 1 TB
2^50 = 1 PB
Yuppers. I usually do bytes/1024 = kilobytes/1024 = megabyes/1024 = gigabytes/1024 = terabytes etc etc. :lol:
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