I recently upgraded my old computer to a new Athalon 1400MHz, and when playing round with some freeware from AMD, I noticed I now had access to all the various newer math CPU instructions rather than just MMX.

What is the difference between all these newer instructions, I have never used MMX before. Intel talks about SIMD where AMD talks about 3DNOW!? Also the version 2 extentions? And when using MMX in masm you can specify .MMX, .XMM or .K3D, what are the difference between these?

Any simple explanations, examples of use, links, tutorials, etc would be greatly appreciated?

Thanks all
Posted on 2001-10-28 21:28:59 by huh
As far as I know :), K3D=3dnow, while .XMM is intels streaming simd.
If you have the athlon4/palomino core, you can use both (though not
the new pentium4 stuff). To find out what to use, you'll have to
find out what instruction set you prefer, if it's available :), what is
best suited for your app... and the cycle counts. No, I have not
looked at this :).
Posted on 2001-10-29 00:06:18 by f0dder
MMX : 64 bit packed instructions. Operate on eight bytes, four words or two dwords at a time.

XMM :128 bit packed instructions. Operate on four single precision floating points at a time.

3DNOW : I have no clue. I don't have an AMD.
Posted on 2001-10-29 04:28:29 by gliptic
Go to and you will find information about their processors.

I hope this help.
Posted on 2001-10-29 14:27:01 by CodeLover
what mmx is to integers is what 3dnow is to floating point numbers. that's how i understand it anyway.
Posted on 2001-10-29 14:51:59 by Sloat
Dr. Dobbs Journal Microprocessor Center has a feature called "Introduction to the Streaming SIMD Extensions in the Pentium III" on the front page. It explains Intel SIMD. For other extensions, I recommend you read some tutorials in the Hugi demo-scene disk-magazine. It has some excellent tutorials in the Code section, plus some interesting articles about the demo-scene as well. For more technical explanations, is the world's leading source of pure technical x86 processor information.
Posted on 2001-10-29 19:09:52 by comrade