Long description

A vertical block is labeled page table and it consists of n number of rows having alternate blank rows from bottom to top. The first segments of the alternate filled rows consisting of two segments are labeled from bottom to top are as follows: 1620, 2032, 2020, 2014, 1213, 1990 which represents time of last use, 2003, 2094. The second segments are labeled 0 which represents Page not referenced during this tick, 1, 1, 1 which represents Page referenced during this tick, 0, 1, 1, 1 which represents R called reference bit. The fifteenth and sixteenth row represents information about one page. Another block labeled 2204 is placed at the upper right end which represents the current virtual time.

A program is also shown near the block as follows.

Scan all pages examining R bit:

If (R equals equals 1) set time of last use to current virtual time. If (R equals equals 0 and age greater than tau) remove this page. If (R equals equals 0 and age less than or equals tau) remember the smallest time.