Custom operations are useable in processor systems for performing functions including multimedia functions. These custom operations enhance a system, such as PC system (TM-1), to provide real-time multimedia capabilities while maintaining advantages of special-purpose, embedded solution, i.e., low cost and chip count, and advantages of a general-purpose processor reprogrammability. These custom operations work in a computer system (TM-1) which supplies input data having operand data, performs operations on the operand data, and supplies result data a destination register (rdes). Operations performed may include audio and video processing including clipping or saturation operations. The present invention also performs parallel operations on select operand data from input registers (rsrc) and stores results in the destination register (rdes).