A great copy of the manual, and the only one I could find anywhere on the net! The circuit diagrams are easily readable, all component values marked and easy to see. A highly appreciated download!
Great Manual. This manual is available no where else. It was exactly what I was looking for.
Text excerpt from page 6 (click to view)
CPU (LSI1: MSM6521-13)
Containing a sound data ROM and a DAC (Digital to Analog Converter), the CPU provides sound waveform in accordance with the pressed key and selected tone. The CPU also drives LEDs in the illuminated keyboard directly. The following table shows the pin functions of LSI1.
In/Out Out In In Out Out In In In/Out In In In In In Out In In Out � In In
Function Keyboard LED drive signal output +5 V source for the built-in LED driver Ground (0 V) source for the built-in LED driver Keyboard LED drive signal output Not used. +5 V source for the built-in LED driver Ground (0 V) source 21.725 MHz clock pulse input/output +5 V source Ground (0 V) source Not used. Connected to ground. Reset signal input. Power OFF: 0 V, Power ON: +5 V +5 V source for the built-in DAC Sound waveform output Ground (0 V) source for the built-in DAC Input terminal for keys and switches Key and switch scan signal input Not used. Ground (0 V) source for the built-in LED driver Keyboard LED drive signal output
C12
Filter Block
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.
AVDD
