An associative memory of the TRIE type is organised in the form of registers of 2.sup.K cells having a portal register from which binary strings are analyzed in successive slices of K bits. Each non-empty cell contains either a pointer or a reference. This reference is issued after the analysis has followed a path formed by the cells designated by the successive slices of K bits in the registers designated by the pointers encountered in these cells in succession. The data is stored in the TRIE memory in response to commands to insert and delete binary patterns of variable length, each associated with a reference, so that when a bit string is analyzed, the reference issued is that associated with the longest of the binary patterns coinciding with the start of the string being analyzed.