Here is the revision history of pixel shaders. Each section contains the changes from the previous version. Significant changes were made to pixel shaders in versions 1.4 and 2.0.

DirectX 9.0

Version 3.0

Pixel Shader 3.0 specification was added.

Version 2.0

Texture and arithmetic instructions can be mixed.

Floating point register support (16- and 32-bit) added.

The cnd, bem, and phase instructions were removed.

The exp, frc, log, rcp, texlb, texlp, dp2add, and rsq instructions were added.

The abs, crs, lrp, max, min, sincos, m4x4, m4x3, m3x4, m3x3, m3x2, nrm, and pow macros were added.

The lrp instruction was changed to a macro.

All source modifiers except negate removed.

All instruction modifiers except saturate removed.

Partial precision hint added.

Co-issue was removed.

Multiple registers are possible as output.

Constants now default to a 0,0,0,0 value.

The number of constant registers was increased to 32.

Sixteen sample registers were added.

DirectX 8.1

Version 1.4

The phase, bem, texcrd, texdepth, and texld instructions were added.

Dropped support for all texture address instructions except texkill.

Texture registers are read only and can be used only in texture addressing instructions.

The read port limit for texture registers was decreased to one because they can't be used in arithmetic instructions.

The number of temporary registers was increased to six.

The read port limit for temporary registers increased to three.

The caps bit for MaxTextureRepeat must be at least eight (from...