ABSTRACT The Second-generation Processor Module for AlphaServer 2100 Systems

systems performs significantly better than the first-generation KN460 module and was designed to be swap-compatible as an upgrade. The KN470 processor module derives its performance improvements from the enhanced architecture of Digital's new Alpha 21164 microprocessor, the synchronous design of the third-level cache and system interface, the implementation of a duplicate tag of the third-level cache, and the implementation of a write-invalidate cache coherence protocol for the multiprocessor system bus. Additional design features such as read-miss pipelining, system bus grant parking, hidden coherence transactions to the duplicate tag, and Alpha 21164 microprocessor write transactions to the system bus back-off and replay were combined to produce a higher performance processor module. The scope of the project required implementing functionality in system components such as the memory, the backplane, the system bus arbiter, and the I/O bridge, which shipped one year ahead of the KN470 module