Data processor priority control unit - allocates priority via last recently used algorithm

摘要

The priority control unit is used to allocate priority to successive variables according to the LRU algorithm (last recently used). The unit has two random-access memories (HPS, NPS) each location being assigned to a variable. The new variables are temporarily stored in an intermediate register (AKR) and first compared with the variables stored in priority registers (HOR1NOR), in two comparators (VG1, 2). If parity is obtained from the initial comparison, the new priority sequence is thus identical to the previous one. Otherwise, the previously higher or lower priority variable is entered into the store registers (HPR, NPR) from both stores (HSP, NSP) under the address (AK) of the new variables. The priority of the new variables is inserted into the up-dated priority sequence in two successive write cycles.