AM 334-01-502
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Fig. 2: Block diagram of a slave processor
4. Digital Rhythm Instruments
Although the functional sequencing of the rhythm and
accompaniment is completely controlled by the master CPU,
the actual sound generation takes place on the instrument
board, which carries the digitally memorized instruments.
The instrument board has its own CPU to control the internal
processing. This CPU, in accordance with its program,
periodically polls its input registers to determine whether
and which instruments should sound. The resulting digital
information then goes to a digital-to-analog converter
(DAC), which builds it into an instrument sound analog
signal. This signal then goes through a lowpass/bandpass
filter and on to an instantaneous volume control circuit.
5. Digital Reverb Unit
The master CPU controls the reverb modes short/long, fast
echo/slow echo.
The digital reverb functions as a processor-supported "real
time" system, whose CPU controls the analog-to-digital
(ADC) conversion, the digital display and the digital-to-
analog (DAC) conversion.
6. Interface
The interface enables the organ to exchange data with:
- Similar instruments via the musical instrument
digital interface (MIDI)
- Home computers via the RS232 interface
- A cassette recorder via the tape interface
To enable such transfers, the parallel digital data from the
master bus is converted to serial data, under control of the
CPU. Incoming serial data, conversely, is converted to
parallel data. For cassette loading or storage, a modem
converts the serial data to audible signals and vice-versa.
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