A texture mapping unit (TMU) is a component in modern graphics processing units (GPUs), historically it is a separate physical processor. A TMU is able to rotate and resize a bitmap to be placed onto an arbitrary plane of a given 3D object as a texture. In modern graphics cards it is implemented as a discrete stage in a graphics pipeline

Graphics pipeline

In 3D computer graphics, the terms graphics pipeline or rendering pipeline most commonly refers to the current state of the art method of rasterization-based rendering as supported by commodity graphics hardware. The graphics pipeline typically accepts some representation of a three-dimensional...

, whereas when first introduced it was implemented as a separate processor, e.g. as seen on the Voodoo2

Voodoo2

The Voodoo2 was a set of three graphics processing units on a single chipset, made by 3dfx. It was released in February 1998 as a replacement for the original Voodoo Graphics chipset. The card ran at a chipset clock rate of 90 MHz and used 100 MHz EDO DRAM, and was available for the PCI interface...

 graphics card.

As rule the number of TMUs, ROPs

Render Output unit

The Render Output Unit, often abbreviated as "ROP", and sometimes called Raster Operations Pipeline, is one of the final steps in the rendering process of modern 3D accelerator boards. The pixel pipelines take pixel and texel information and process it, via specific matrix and vector operations,...

, and pixel shaders are equal.