Circuit Description - Lexicon 960L Service Manual

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Figure 1-1 Reverb Card Block Diagram

Circuit Description

This section is a page by page description of the 960L Reverb Processor schematic.
PCI Bus (sheet 1)
The PCI bus is a 33 MHz, 32 bit multiplexed address/data bus that serves as the interface between the
Reverb Card and the host Pentium processor. The DSP 56301 provides an integrated, glue-less interface
to the PCI bus including all of the configuration and address mapping registers. Master and slave modes
are supported. The Reverb card requires 12V, 5V, and 3.3V.
56301 DSP Microprocessor (sheet 2)
The 56301 operates at 3.3V which is provided by the PCI connector. The 56301 is clocked from an external
6 MHz crystal (Y1, sheet 2) and the on-chip PLL is used to generate an 80 MHz clock which is output as
DSP_CLKOUT. The reset control chip (U37) creates a reset pulse with a minimum duration of 20ms as
required by the 56301. The Once Port is used for development and is not populated for production cards.
The 56301 moves samples to/from the T-MIX devices and its internal memory using the DSP bus, which
appears on the right hand side of the chip symbol. The DSP56301 has internal address decoders that are
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