According to our model of pregenetic molecular coding, nucleobase doublets anticodons were, by stereochemical affinities, the primary codons for amino acid letters of the primitive peptide sequences. Such doublets, anticipating the base sequences of the «modern» triplet codons of the reading strand of DNA would have been initially stabilized along polyphosphate chains by phosphoamidic dehydrating condensation with tripolyphosphate into riboseless prenucleic acids.