Cache tag
= Cache tag
Metadata identifying which eligible backing <cache block> a valid <cache slot> currently holds. In the <fully associative cache> example, the <cache tag> is the full <cache block> number $q$; in the two-slot <direct-mapped cache> example, the slot supplies $q\bmod2$ and the <cache tag> can store $\lfloor q/2\rfloor$ using the <floor function>.