MERSI protocol was used by the computer that was a fourth generation of what type of processors?
MERSI protocol The MERSI protocol is a cache coherency and memory coherence protocol used by the PowerPC G4. The protocol consists of five states, Modified (M), Exclusive (E), Read Only or Recent (R), Shared (S) and Invalid (I). The M, E, S and I states are the same as in the MESI protocol. The R state is similar to the E state in that it is constrained to be the only clean, valid, copy of that data in the computer system. Unlike the E state, the processor is required to initially request ownership of the cache line in the R state before the processor may modify the cache line and transition to the M state. In both the MESI and MERSI protocols, the transition from the E to M is silent.
PA-7100 The PA-7100 is a microprocessor developed by Hewlett-Packard (HP) that implemented the PA-RISC 1.1 instruction set architecture (ISA). It is also known as the PCX-T and by its code-name Thunderbird. It was introduced in early 1992 and was the first PA-RISC microprocessor to integrate the floating-point unit (FPU) on-die. It operated at 33 - 100 MHz and competed primarily with the Digital Equipment Corporation (DEC) Alpha 21064 in the workstation and server markets. PA-7100 users were HP in its HP 9000 workstations and Stratus Computer in its Continuum fault-tolerant servers.