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CIRCUIT DESCRIPTIONS

TR-707 and TR-727 are designed based on the same Circuit configuration, havmg morc in common with each other, The diłferences between two models are sound data, component values in sevcral audio stages and a couple of pin connections at IC30 o* Voice board

Both models derive all rhythm sounds Irom PCM-encoded samples of real sounds stored in ROM. Each waveform is stored either mdependently (e.g. CYMBAŁ} or together with another waveform as shown in Tables 1 and 2. Accordingly, sound reproducing circuits are dassified into two: multiplex and single. The follow-ing description focuses on PCM sound reproduction system, taking TR-707 circuits as a representative.

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MULTIPLEX SOUND SYSTEM BŁOCK DIAGRAM

MULTIPLEX SOUND PROCESSING

MULTIPLE ADDRESSCOUNTERS

IC30 RD63H114 on Voicing Board is a custom-LSilcall-ed Gate Array) designed for usc in PCM-sound multi-rhythm Systems The LSI assumes the key role in the TR 707 sound system. It incorporates a master dock generator, timing generator and 8 13-bit address ooun-tcrs. The timing generator, not only supplies clocks to these counters for generating address bits. but also feeds peripheral circuits with various timing clocks to sync the entire system operation. Of these timing clocks. A, 8 and C together make a channel-seiect codę for signal-ing the ROMs flCs 34. 35). MUX IC40 and DMUX IC41 which voice is being addresscd by an address counter in IC30.

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