I believe the two chips shown below to be N7970 and N7975. TCR lists the mold as "Wico" on both. Similar chips are shown on Paul Hegge's site are listed as "RTP". I notice TCR also uses RTP as a mold description on some of the Let it Ride chips. Is Wico the mold and R.T. Plastics the maker, and the terms interchangeable, or is there a some distinguishing characteristic that separates them?