Throughput computing is the underlying strategy of Sun's UltraSPARC processors, which are designed to significantly increase real-world application processing throughput. At the heart of this strategy is Chip Multithreading (CMT), a design concept that would eventually allow processors to execute tens of threads simultaneously. The dual-threaded UltraSPARC IV processor marks the first milestone in Sun's CMT processor roadmap.The UltraSPARC IV processor is binary compatible with previous generations of SPARC processors. This is consistent with Sun's commitment to protecting customers' investments in software and training.