Advanced Micro Devices Inc (AMD)

[sgolds]

wbmw, perhaps I am old-fashioned in my terminology, but I always considered 'double precision' to mean twice the size of the standard register word. In the case of AMD64, that would mean 128 bits.

So, I decided to see if my use of the language is correct in this case. It is.

http://www.amd.com/us-en/Processors/DevelopWithAMD/0,,30_2252_875_4622,00.html

Note the 64-bit and 128-bit Media instructions.

If you download & look in manual 4, you will see this statement on prefix p. xiv:

128-bit media instructions
Instructions that use the 128-bit XMM registers. These are a combination of the SSE and SSE2 instruction sets.

Chapter 1 goes into a lot more detail. Looks like they did go to 128-bit registers to come up with a more powerful SSE, SSE2 set.