A DNA version of the self-assembly model of computing, feasible using currently available laboratory techniques, is proposed. Input signals are coded into unmethylated and methylated oligonucleotides which then hybridize with a backbone that contains complementary sequences. Different input signal patterns are thus represented as DNA duplexes with distinctly different conformational dynamics, in particular different equilibria of B and Z DNA. The pattern classification activity of the system is mediated by the interactions that lead to the secondary structural organization. Circular dichroism may be used for readout.