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HWjarausch
Journeyman III

Phenom II - does it have a long double type ?

What does 128 bit floating point mean?

Hi, what does it mean when the specs for the Phenom II talk about 128 bit floating point?

Is it just the parallel processing of two 64-bit floating point numbers or is there hardware support for a real 128bit floating point type, i.e. with a significantly longer mantissa than 64 bits?

Thanks for your info,

Helmut.

 

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avk
Adept III

Phenom II - does it have a long double type ?

No one of x86-CPU does support a native 128-bit floats. The maximum is 80-bit floats, which can be used by the legacy x87-instructions.
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bridgman
Staff
Staff

Phenom II - does it have a long double type ?

I think this relates to the SIMD (SSEx) instructions; the older AMD CPUs used to have a 64-bit wide ALU path so took two clocks to process (4x32 bit) or (2x64 bit) words -- with a 128-bit data path the same work can be done in a single clock. So... parallel processing of 2 64-bit numbers etc...

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backlink
Journeyman III

Phenom II - does it have a long double type ?

woah.. all this computer terms is really a pain in the ***** for me to understand.. but bridgman explanation is great as i think i get th picture (just a little)

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