Symbolic language data processing system

In a data processor programmable in a symbolic processing language and having a main memory wherein each location has a multi-bit actual address comprising a page nummber and an offset number, central processing means for operating on data and for storing data in the main memory with an associated virtual address comprising a virtual page number and an offset number and means for converting the virtual address to the actual address, the improvement wherein the converting means comprises:

• a first cache memory having a table of actual addresses for a plurality of virtual addresses, means for performing a first hash function on a given virtual page number to reduce the number of bits thereof to form a map address corresponding to the hashed virtual page number;
• at least one addressable map converter for storing the actual page number and the given virtual page number corresponding thereto in the map address corresponding to the hashed virtual page number;
• means for indicating that a given virtul address is not in the first cache memory;
• means responsive to an indication that a given virtual addresses is not in the first cache memory for hashing the given virtual page number and applying same to the at least one addressable map converter;
• means for comparing the given virtual page number with the virtual page number from the at least one addressable map converter whereby a favorable comparison indicates that the stored actual page number is in the at least one addressable map converter;
• and means for applying the accessed actual page number and the original offset number to the main memory when there is a favorable comparison to thereby access the location corresponding to said access actual page number and on final offset number.