Internal Apple IIGS sound system/interface developer's binder, totaling approximately 144 pages, with sections including: "Sound Tools ERS, Revision 2.1, March 2, 1987," "Note Synthesizer ERS, Revision 00:50, September 25, 1986," "MIDI Tool Set ERS, Revision 1.1.4, June 17, 1988," and "The Note Sequencer ERS, Revision 1.1P, June 2, 1988." In fine condition. The Apple IIGS, developed under the internal codename 'Cortland,' featured an Ensoniq ES5503 8-bit wavetable synthesis chip.
