Additional-reference-bits algorithm
We can keep an 8-bit byte for every page in a table in memory. The operating system shifts the reference bits right 1 bit, discarding the low-order bit. These 8 bits sift register have the history of page used for previous eight time periods. A page with a history value of 11000100 has been used more just than has one with 01110111. The page with the lowest number is the LRU page, and it can be changed.