Boss PD-1 Rocker Distortion
The Boss PD-1 was a treadle controlled distortion pedal released in the early 1980's. The treadle is used to adjust the amount of gain much like the sweep of a wah and on the face the pedal features Level, Tone and Min Level Distortion knobs. There are also two switches under the treadle, one controlling the bypass and one for "warp" mode that activates a high gain circuit momentarily.
The PD-1 deceptively has very little in common with the DS-1 apart from the orange colour used.