Abstract: Data processing system for high-speed reproduction of musical recordings at a point-of-sale terminal utilizes optical CD music ROM banks of master programs prerecorded by a Dolby ADM (adaptive delta modulated) technique to condense their "information" content. Condensation permits higher data throughput during high-speed reproduction. In a "premastering" process to make encoded masters, a special multiplexer board provides interfacing between Dolby ADM digital audio data and a conventional data processing system. The multiplexer board performs computer-like data blocking and also writes a unique sync code directly in the data block. The data processing system also catalogs and edits the blocked digital audio; places encrypted catalog, pricing, and other indicia in the data file representing the music; and sends the data file to convention 16-bit PCM file writer for making the encoded CD music ROMs which contain the ADM data representing the encoded audio program.