A device and method for producing Inter Symbol Interference (ISI) scaling of S-Parameter Touchstone files for the generation of ISI scaling effects on serial data patterns by direct digital synthesis is described. The features of the present invention allow user to set parameters such as data rate, voltage amplitude, encoding scheme etc. as per requirements for the serial data patterns. An ISI scaling value is selected and applied to an S-Parameter Touchstone file representing transmission path effects. The serial data pattern parameters and the ISI scaling value used with the S-Parameter Touchstone file are compiled to generate a digital data waveform record file. The digital waveform record file is applied to a waveform generation circuit for converting the digital data into an analog serial data pattern with ISI scaling effects.