Abstract: An apparatus and method for digitally displaying with a thermal printer the continuous time varying signal generated by a chromatograph. The apparatus generates different graphic forms distinguishing chromatograph peaks representing a solvent from the chromatograph peaks indicative of compounds dissolved in the solvent. The continuous chromatograph signal is sampled at predetermined intervals at the onset of a peak. These sample values are stored in a memory that is sequentially addressed with one address corresponding to each sample. From the samples taken, individual bits of baseline data are calculated and stored in memory having addresses corresponding to those wherein their respective corresponding sample values are stored. Instructions for printing different graphic patterns are also stored and called-up to print a display indicative of the sample values and corresponding base-line information so that a reader can easily distinguish the peaks and baseline.