AGEIA PhysX
The first processor to be advertised as a PPU was called the PhysX chip, introduced by a fabless semiconductor company called AGEIA. Games wishing to take advantage of the PhysX PPU must use AGEIA's PhysX SDK, (formerly known as the NovodeX SDK).
It consists of a general purpose RISC core controlling an array of custom SIMD floating point VLIW processors working in local banked memories, with a switch-fabric to manage transfers between them. There is no cache-hierarchy as in a CPU or GPU.
The PhysX was available from three companies akin to the way video cards are manufactured. ASUS, BFG Technologies, and ELSA Technologies were the primary manufacturers. PCs with the cards already installed were available from system builders such as Alienware, Dell, and Falcon Northwest.
In February 2008 after Nvidia bought Ageia Technologies and eventually cut off the ability to process PhysX on the AGEIA PPU and NVIDIA GPUs in systems with active ATi/AMD GPUs, it seemed that PhysX went 100% to Nvidia. But in March 2008, Nvidia announced that it will make PhysX an open standard for everyone, so the main graphic-processor manufacturers will have PhysX support in the next generation graphics cards. Nvidia announced that PhysX will also be available for some of their released graphics cards just by downloading some new drivers.
See physics engine for a discussion of academic research PPU projects.
Read more about this topic: Physics Processing Unit