What is Close to Metal (CTM)?
Close to Metal (CTM) is an application programming interface (API) designed to introduce developers to the underlying parallel processing architecture of graphics hardware.
It was originally published by ATI Technologies to allow general graphics processing unit (GPGPU) processing or custom programming and control of the graphics card / hardware.
CTM primarily enabled exposure and provided software developers with access to previously unavailable low-level graphics card features. This included the instructions, processor set architecture and memory. It allowed developers to build applications that took advantage of a number of unused GPGPU capabilities and performed faster than standard central processing units (CPUs). It also replaced the OpenGL and DirectX APIs for programmers. The CTM was integrated and supported by ATI R580 GPU processor cards.
After Advanced Micro Devices, Inc. (AMD) acquired ATI, the CTM was replaced by the OpenCL framework, which provided improved access and control over the capabilities of the graphics processor.