Specifications

S1C62N82 TECHNICAL HARDWARE EPSON I-75
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Melody Generator)
The block diagram of the melody generator is shown in
Figure 4.11.1. The note and interval data of the melody to
be played is pre-written on the melody ROM. The interval
data of the melody ROM is used to specify the scale ROM
address and according to the scale ROM data read from it,
the interval generating circuit generates the interval. The
output is controlled at the melody output control circuit and
is output at the MO and R12 terminals. The note generator
is generated according to the melody ROM data. The output
is entered in the melody ROM address counter; every time
the playing of a note is completed, one address is
incremented. This results in continuous melody being
automatically played. The playing tempo is created by the
tempo generator based on the signal which divided the
oscillation frequency in the oscillation circuit. Through the
mask option, 2 types of tempo may be selected from among
16 types. Moreover, the division ratio of the divider may be
modified by software and 4 types of playing speed can be
implemented. Envelope function may also be added to the
output melody and R12 output may be implemented by
setting it to correspond with the envelope.
Frequency
booster
Interval
generating
circuit
Melody
output
control circuit
Scale
ROM
Melody
interrupt
generator
Address
register
Address
counter
Melody
ROM
End-of-melody
signal
generator
Controller Divider
Tempo
generator
Note
generator
To CPU
R12
MO
32,768 Hz
Address bus
Data bus
Data bus
Address bus
Fig. 4.11.1
Melody generator
block diagram