DescriptionOpen Coherent Accelerator Processor Interface (OpenCAPI) is a new industry standard architecture agnostic device interface. OpenCAPI enables the development of host-agnostic devices which can coherently connect to any host platform which supports the OpenCAPI standard, providing device capability to coherently cache host memory to facilitate accelerator execution, perform DMA and atomics to host memory, send messages and interrupts to the host, and act as a host memory home agent. OpenCAPI utilizes high-frequency differential signaling technology while providing high bandwidth in addition to low latency needed by advanced accelerators. OpenCAPI encapsulates the serializing cache access and address translation constructs in high speed host silicon technology to minimize overhead and design complexity in attached silicon such as FPGAs and foundry ASICs. Finally, OpenCAPI architecturally ties together transaction layer, link layer, and physical layer attributes to optimally align to high SERDES ratios and enable high bandwidth, highly parallel exploitation of attached silicon.