PPUs

PPUs, or physics processing units, are specialized microprocessors designed to accelerate real-time physics simulations in computer graphics and video games. The goal is to offload computationally intensive physics tasks from the main CPU to a dedicated co-processor, enabling more detailed rigid body dynamics, collisions, joints, fluids, and soft-body simulations.

The most notable implementation came from Ageia Technologies with the PhysX PPU, released in the mid-2000s. The card contained dedicated processing hardware and memory and connected to the system via a standard interface, running the PhysX engine through its API. Developers could integrate physics-heavy features by targeting the PPU, seeking higher simulation fidelity and consistent performance in complex scenes.

Adoption of discrete physics accelerators faced several challenges, including cost, integration complexity, and the rapid advancement of CPU and GPU capabilities. As CPUs gained more cores and GPUs acquired powerful general-purpose compute capabilities, many developers migrated physics workloads to CPUs or leveraged GPU acceleration. In 2008, NVIDIA acquired Ageia and began integrating PhysX into its GPUs, reducing the need for standalone PPUs.

Current status: the term PPU is largely historical in consumer computing. Today, physics simulations are typically performed on CPUs or GPUs using general-purpose compute pipelines (such as CUDA or DirectCompute) or through physics engines that exploit GPU acceleration. While dedicated PPUs are uncommon now, their emergence influenced the shift toward hardware-accelerated physics in modern graphics hardware. See also PhysX, GPU computing, and real-time physics engines.