An application-specific instruction-set processor (ASIP) is a component used in System-on-a-Chip design. The instruction set of an ASIP is tailored to benefit a specific application. This specialization of the core provides a tradeoff between the flexibility of a general purpose CPU and the performance of an ASIC.
Some ASIPs have a configurable instruction set. Usually, these cores are divided into two parts: static logic which defines a minimum ISA and configurable logic which can be used to design new instructions. The configurable logic can be programmed either in the field in a similar fashion to an FPGA or during the chip synthesis.