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. C0000089h - AMD K6-III - L2AAR (Level 2 CACHE ACCESS REGISTER) Size: 53 bits Bitfields for AMD K6-III Level 2 CacheCaching is a method of increasing performance by keeping frequently-used data in a location which is more quickly accessed. The most common caches are disk caches (store disk sectors in RAM) and RAM caches (store portions of main memory in special high-speed RAM which may be accessed as fast as the CPU is capable of accessing memory). See also Delayed Write, Write-Through. Access Register: Bit(s) Description (Table R0072) 52 "T/D" select tag or data =1 access cache tag =0 access data 51-50 reserved 49-48 way 47-38 set number 37 line number 36-35 octet within line 34 select high/low DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. 33-32 reserved ---T/D=0 --- 31-0 data ---T/D=1 --- 31-15 tag 14-12 reserved 11-10 Line1 MESI state 11 = Modified 10 = Exclusive 01 = Shared 00 = Invalid 9-8 Line2 MESI state (as for bits 11-10) 7-0 LRU states (two bits per way) 00 most recently used 11 least recently used