[lispm]

Things evolved in the 70s. Hash tables were added over time, with some alternatives were using some tree like search. Usually the first thing was to make the symbol table not a list -> making the symbol table a hash table was reportedly done in 1971 by Jon L White. Tag bits then also were not a part of the pointers (with only very few exceptions), but a part of the data object (numbers, strings, arrays, symbols, ..).