MSR(Model-Specific Register) Additional, indirectly-accessible, registers containing control or status information about various aspects of the processor such as caches, performance counters, and the like. These registers, accessible via the RDMSR and WRMSR instructions, were added with the Pentium and later-model 486 processors. 000001E0h - Pentium Pro - "ROB_CR_BKUPTMPDR6" Size: >= 3 bits Bitfields for Pentium Pro MSR(Model-Specific Register) Additional, indirectly-accessible, registers containing control or status information about various aspects of the processor such as caches, performance counters, and the like. These registers, accessible via the RDMSR and WRMSR instructions, were added with the Pentium and later-model 486 processors. 000001E0h: Bit(s) Description (Table R0050) 63-3 ??? 2 Fast String Enable (default is enabled) 1-0 reserved Note: if bit 2 is set, REP MOVS moves 64 bits each clock cycle if both source and target are QWORD-aligned