A waveform viewer implemented method of generating and manipulating user specified language simulation code such that an integrated circuit digital design can be modified. The visual capabilities of the waveform viewer allow a plurality of inputs for processing. The previous test's user specified language lines and the original signal waveforms are viewable on the same screen as the new code lines and waveforms. The waveform viewer also displays the contents of the portable reusable code portable reusable coded storage device. Each line of code and every signal can be manipulated by the user within the waveform viewer. The modified code output is applied to the test sequence through the waveform viewer, and the integrated circuit is retested with the new code. After modifications to the integrated circuit are complete, the proved device's stored user specified language can be transported to and inserted in other device architectures.