| 摘要 |
PROBLEM TO BE SOLVED: To provide a least recently used(LRU) fault detection device whose HW quantity required for LRU fault detection is small by efficiently detecting an illegal pattern through the use of the feature of an LRU information illegal pattern. SOLUTION: When TLB 1 is hit, TLB transmits a TLB hit signal and a TLB hit entry number to an LRU circuit 2. The LRU circuit 2 holds LRU information and updates LRU information. A replacement address generation circuit 3 generates and outputs a replacement address (oldest entry number) from LRU information received from the LRU circuit 2. An oldest (latest) entry decoding possible pattern detection circuit 4 transmits '1' when oldest (latest) entry decoding is possible and '0' when decoding is impossible to a NAND gate 6 when it receives LRU information from the LRU circuit 2. The NAND gate 6 outputs '1' showing that the LRU circuit 2 breaks down when either input is '0'. |
