3DNow!

3DNow! is a deprecated extension to the x86 instruction set developed by Advanced Micro Devices (AMD). It adds single instruction multiple data (SIMD) instructions to the base x86 instruction set, enabling it to perform vector processing of floating-point vector operations using vector registers, which improves the performance of many graphics-intensive applications. The first microprocessor to implement 3DNow! was the AMD K6-2, which was introduced in 1998. When the application was appropriate, this raised the speed by about 2–4 times. However, the instruction set never gained much popularity, and AMD announced on August 2010 that support for 3DNow! would be dropped in future AMD processors, except for two instructions (the PREFETCH and PREFETCHW instructions). These two instructions are also available in Bay-Trail Intel processors. 3DNow! was developed at a time when 3D graphics were becoming mainstream in PC multimedia and games. Realtime display of 3D graphics depended heavily on the host CPU's floating-point unit (FPU) to perform floating-point calculations, a task in which AMD's K6 processor was easily outperformed by its competitor, the Intel Pentium II. As an enhancement to the MMX instruction set, the 3DNow! instruction-set augmented the MMX SIMD registers to support common arithmetic operations (add/subtract/multiply) on single-precision (32-bit) floating-point data. Software written to use AMD's 3DNow! instead of the slower x87 FPU could execute up to four times faster, depending on the instruction mix. The first implementation of 3DNow! technology contains 21 new instructions that support SIMD floating-point operations. The 3DNow! data format is packed, single-precision, floating-point. The 3DNow! instruction set also includes operations for SIMD integer operations, data prefetch, and faster MMX-to-floating-point switching. Later, Intel would add similar (but incompatible) instructions to the Pentium III, known as SSE (Streaming SIMD Extensions).