Pentium MMX Processor:

Pentium MMX Processor – MMX stands for Multimedia Extension, Multiple Math Extension, or Matrix Math Extension. The MMX is a Single Instruction Multiple Data (SIMD) instruction and it was designed by Intel in 1996. The MMX TM technology has the following new extensions in Intel Architecture 32-bit Pentium processor:

• It has eight MMX registers such as MM0-MM7.
• Four MMX data types such as packed bytes, packed words, packed double words and quad words. In packed bytes, eight bytes are packed into one 64-bit quantity. In packed words, four 16 bit words are packed into one 64-bit quantity. In packed double words, two 32-bit double words packed into one 64-bit quantity. The quad word is one 64-bit quantity.
• It has a 57 MMX instruction set.
• MMX technology supports saturating arithmetic and wraparound mode.

In 1997, Intel developed Pentium MMX processor incorporating the multimedia extension (MMX) tech­nology for different multimedia applications such as 2D and 3D image processing. In multimedia applica­tions, most of the operations involve pixels. During representation of a color image, one pixel consists of three components such as red, green and blue. Each component of a pixel is an 8-bit integer. The intensity of each component of a pixel can be varied from 0 to 255. The image processing and image compression opera­tions require matrix multiplication and matrix convolution type computations and also require operations on multiple numbers of pixels simultaneously. Therefore, all multimedia applications need a Single Instruction Multiple Data (SIMD) type architecture.

The Pentium MMX processor has eight 64-bit MMX registers known as MM0 through MM7. The MMX instructions access the MMX registers directly. These registers can be used to perform computations with MMX data types. Intel provides a set of 57 MMX instructions which are used for improving graphic perfor­mance in image processing, image filtering, image enhancement and coding, etc. Pentium processors (P5) can operate on two pixels simultaneously, whereas MMX instructions of Pentium MMX processor can oper­ate eight pixels at the same time. The Pentium MMX processors has the following drawbacks:

• MMX instructions work with integers only, though 2D and 3D graphics often require floating point arithmetic operations.
• MMX instructions and floating-point unit instructions can share registers, but MMX and FPU instructions do not work simultaneously.