A commercial multithreaded RISC processor

Implementation of a coarse-grained hardware-multithreaded processor for use in the IBM AS1400 uses a PowerPC architecture that supports two threads. Hardware multithreading is a technique for tolerating memory latency by utilizing otherwise idle cycles in the CPU. This requires the replication of the processor architecture registers for each thread. Replication is not required for the majority of processor logic such as instruction cache, data cache, TLB, instruction fetch and dispatch mechanisms, branch units, fixed-point units, floating-point units, and storage-control units.