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Description  |
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BACKGROUND OF THE INVENTION
The present invention relates to electronic musical instruments which
employ storage means such as a memory and generate musical tones through
the access of the storage means.
Conventional electronic musical instruments have performance data input
means such as a keyboard; control means which generates control parameters
such as a command for triggering the musical tone generation in response
to the input data inputted through the performance data input means; and a
tone generator which generates musical tones based on the control
parameters. Generally, the tone generator provides registers for storing
musical tone parameters such as a current amplitude value of the musical
tone waveform and a state of the envelope waveform of the generated
musical tone. In the tone generator, calculation operations are
sequentially executed based on these stored musical tone parameters and
the musical tone parameters are sequentially updated based on the
calculated result. Through these operations, the tone generation of the
musical tone waveform designated by the control means is carried out.
Furthermore, in general electronic musical instrument, a RAM (Random
Access Memory) is provided as a storage means for storing the control
parameters mentioned above and is used by the control means.
Meanwhile, there are cases in which the control means observes the state of
the musical tone generation by the tone generator and controls the
operation of the tone generator based on the observation. For example,
such a case appears in the electronic musical instruments which have a
plurality of sound channels and are capable of generating a plurality of
musical tones simultaneously and independently by using the sound
channels. In these electronic musical instruments, when a new key-on event
is detected from the keyboard, the control means selects one of the sound
channels through which the musical tone having the lowest envelope value
is generated and assigns the selected sound channel for generating the
musical tone corresponding to the new key-on event. In such a case, the
control means of the conventional electronic musical instrument should
read out the musical tone parameters which indicate the state of the
musical tone generation and are stored in the control registers of the
tone generator. Such an access operation is very heavy load for the
control means and therefore it is difficult to provide a high-performance
electronic musical instrument. Furthermore, in the case where the number
of the sound channels of the tone generator is large, a large number of
registers should be provided in the tone generator for storing the musical
tone parameters and a large scale control circuit should be provided for
controlling the access of the registers. Therefore, the electronic musical
instrument becomes high cost.
Furthermore, there are cases in which the same musical tones are repeatedly
generated to obtain a sound having a special effects such as a echo sound.
In these case, the control means should generate the musical tone
parameters every time each one of the musical tones is generated by the
tone generator although there are few difference between the musical tone
parameters to be generated and the musical tone parameters which have been
previously generated.
SUMMARY OF THE INVENTION
In consideration of the above, it is an object of the present invention to
provide an electronic musical instrument having a high cost performance
ratio in which the load of the control circuit for controlling the tone
generator is reduced and the sizes of the control circuit and the memory
for storing the control parameters is also reduced.
In an aspect of the present Invention, there is provided an electronic
musical instrument comprising a common memory for storing a plurality of
musical tone parameters; a tone generator for generating a musical tone
based on the musical tone parameters stored in the common memory and
writing a musical tone parameter in the common memory, which indicates the
current state of the musical tone being generated by the tone generator;
and a control section for directing the tone generator to generate a
musical tone by writing the musical tone parameters corresponding to the
musical tone in the common memory and controling the tone generation of
the tone generator by monitoring the current state of the musical tone
based on the musical tone parameter stored in the common memory.
In the aspect of the present invention, there is further provided an
electronic musical instrument comprising a first memory for storing a
plurality of musical tone parameters; a second memory means for storing a
control program to thereby control the electronic musical instrument; a
control processor for reading out the control program from the second
memory means, controling the electronic musical instrument based on the
read out control program and being capable of performing the reading or
writing operation of the musical tone parameters to the first memory in
synchronization with a first time slot; a reading circuit for reading out
the musical tone parameters during a second time slot, the timing of which
is different from that of said first time slot; and a tone generater for
generating a musical tone based on the musical tone parameters read out
from the first memory by the reading means.
In the aspect of the present invention, there is further provided an
electronic musical instrument comprising a common memory having a
plurality of memory areas each of which stores musical tone parameters
corresponding to a musical tone to be generated; a tone generator having a
plurality of tone generation channels, respectively corresponding to the
plurality of memory areas, each of which generates a musical tone based on
the musical tone parameters stored in the corresponding memory area, each
of the plurality of tone generation channels writing the current state of
a musical tone being generated thereby as a musical tone paremeter in the
corresponding memory areas; and a control section for monitoring the
current states of the musical tones generated by the plurality of tone
generating channels based on the musical tone parameters stored in the
memory areas of the common memory, the control means, in response to a
tone generation designation, selecting one of the plurality of tone
generation channels based on the current states and writing a musical tone
parameter corresponding to the tone generation designation in a memory
area corresponding to the selected tone generation channel so as to
generate a desired musical tone.
In the aspect of the present invention, there is further provided an
electronic musical instrument comprising a common memory having a
plurality of memory areas each of which stores musical tone parameters; a
tone generator having a plurality of tone generation channels each of
which generates a musical tone based on the musical tone parameters stored
in the memory areas corresponding thereto; and a control section for
selecting on of the plurality of tone generation channels in response to a
tone generation designation and for writing the musical tone parameters,
which correspond to a musical tone to be generated, in one of the
plurality of memory areas corresponding to the selected tone generation
channel, and the control section, when same musical tone as a musical tone
generated by a tone generation channel is repeatedly to be generated,
operating the following processing steps:
(a) reading out the musical tone parameters of the musical tone which has
been generated; and
(b) writing the read-out musical tone parameters in another of the
plurality of memory areas to generate the same musical tone again.
Further objects and advantages of the present invention will be understood
from the following description of the preferred embodiments with reference
to the drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram showing the configuration of an electronic
musical instrument of a preferred embodiment of the present invention.
FIG. 2 is a time chart showing the relationship between sampling periods,
sound channels and time slots defined in the electronic musical instrument
shown in FIG. 1.
FIG. 3 is a memory map showing the content of a parameter ROM 6 of the
electronic musical instrument showin in FIG. 1.
FIG. 4 shows a loop-regeneration control which is performed in the
electronic musical instrument shown in FIG. 1.
FIG. 5 shows an example of a envelope waveform generated in the electronic
musical instrument shown in FIG. 1.
FIG. 6 is a memory map showing the content of a common RAM 7 of the
electronic musical instrument shown in FIG. 1.
FIG. 7 is a block diagram showing the configuration of a tone generating
section 51 provided in the electronic musical instrument shown in FIG. 1.
FIG. 8 is a block diagram showing the configuration of an envelope
generator 600 provided in the electronic musical instrument shown in FIG.
1.
FIG. 9 is a block diagram showing the configuration of a RAM accesss
control section 8 provided in the electronic musical instrument shown in
FIG. 1.
FIG. 10 is a time chart showing the waveforms of control signals which are
supplied to the RAM access control section 8 shown in FIG. 9.
FIGS. 11 to 13 are flow charts showing the operation of a CPU provided in
the electronic musical instrument shown in FIG. 1.
FIGS. 14 to 16 are time charts showing the operation of the electronic
musical instrument shown in FIG. 1.
FIG. 17 shows the envelope waveform of an echo sound generated by the
electronic musical instrument shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Configuration of the Preferred Embodiment
(1) Overall configuration
FIG. 1 is a block diagram showing the configuration of an electronic
musical instrument of a preferred embodiment of the present invention. In
FIG. 1, 1 designates a control section which controls the other elements
in the electronic musical instrument. 2 designates a keyboard on which a
plurality of keys are provided. 3 designates a panel switch group which
consists of a plurality of switches, the on/off states of which are
changed by the operation of the corresponding operational members provided
on the control panel of the electronic musical instrument. 4 designates a
panel display which is provided on the control panel for displaying
information such as a name of the function which is currently activated. 5
designates a tone generator which generates musical tone signals in
response to the note-on command which triggers the tone generation. The
tone generator 5 is a time-division-controlled tone generator which can
simultaneously generates twelve kinds of musical tones. Waveform data of
each musical tone are sequentially generated in synchronization with a
sampling clock having a predetermined sampling period Ts and the
calculations for determining the waveform are achieved in a
time-division-controlled manner by using one of sound channels CHi (i=0 to
11) which are obtained by dividing a sampling period Ts by twelve.
Furthermore, one sound channel is divided into sixteen time slots Tk (k=0
to 15). The calculations for determining one waveform data are carried out
by using these sixteen time slots. FIG. 2 shows the relationship between
the sampling period Ts and the sound channels CHi (i=0 to 11) and the time
slots Tk (k=0 to 15). In FIG. 1, 6 designates a parameter ROM (Read Only
Memory) which stores musical tone parameters which are used for generating
musical tones. The detail description for the musical tone parameter will
be given later. The parameter ROM 6 is connected to the tone generator 5
via a ROM bus ROMBUS which consists of an address bus ABROM and a data bus
DBROM.
7 designates a common RAM which is used as a storage means for storing the
control data which are used by a CPU 11 of the control section 1 to
control the operation of the electronic musical instrument and is also
used as a storage means for storing the musical tone parameters which are
used by the tone generator 5 to generate musical tone signal. The musical
tone parameters stored in the common RAM 7 contain data used for the CPU
11 and the tone generator 5 independently and also contain the following
data:
A. The data which are given to the tone generator 5 by the CPU 11 such as a
note-on command and tone color designation data.
B. The data which indicate the current state of the musical tone generation
of tone generator 5 and are monitored by the CPU 11 to control the
operation of the electronic musical instrument.
Thus, that is to say, the common RAM 7 acts not only a storage means but
also a bi-directional information transfer means through which the
bi-directional communication between CPU 11 and tone generator 5 is
carried out. The detail description for the data stored in the common RAM
7 will be given later. The common RAM 7 is accessed via a RAM bus RBUS
which consists of a data bus DB.sub.R, an address bus AB.sub.R and a
read/write line R/W.sub.R. The data bus DB.sub.R, address bus AB.sub.R and
read/write line R/W.sub.R are respectively connected to the data input
terminals, address input terminals and read/write input terminal of the
common RAM 7.
8 designates a RAM access control section which switches the connection
configuration between the CPU 11 of the control section 1, the tone
generator 5 and the common RAM 7. 9 designates a write operation detecting
section which observes the data writing operation to the common RAM 7. When
the first parameter of the musical tone parameter corresponding to the
musical tone to be generated (in this embodiment, the first parameter is
lower-bit data of voice number VnL) is written in the common RAM 7, the
write operation detecting section 9 outputs "1" signal as a load signal
LOAD which commands to the tone generator 5 the reading of the parameter
corresponding to the musical tone to be generated. 10L and 10R
respectively designates left and right channels sound systems which output
left and right channels musical tone signals LOUT and ROUT, which are
generated by tone generator 5, as musical sounds. 100 designates a timing
signal generator which generates timing signals for determining the
execution timing of the operations which are to be carried out by the
control section 1, the RAM access control section 8 and the tone generator
(2) Configuration of control section 1
The control section i consists of the CPU 11, a timer 12, a ROM 13, a
parallel I/O (Input/Output) interface 14, a driver 15 and the
above-mentioned CPU bus CPUB which connects the elements 11 to 15
together. In the control section 1, the CPU 11 controls the other elements
of the electronic instrument based on the control programs stored in the
ROM 13. The timer 12 is provided as a time count means. A time count data
is set in this timer by the CPU 11 via the CPU bus CPUB. The timer 12
outputs a timer interrupt signal to the CPU 11 when a time corresponding
to the time count data lapses. The states of the keys of the keyboard 2
and the on/off states of the switches of the panel switch group 3 are
sensed by the CPU 11 via the parallel I/O interface 14 and via the CPU bus
CPUB. The CPU 11 outputs the data used for the musical tone generation such
as a note-on command, a tone color designation data to CPU bus CPUB based
on the data sensed via the parallel I/O interface 14. Furthermore, the CPU
11 outputs display data which indicate information such as a name of the
currently activated function to the driver 15 to display the information
on the panel display 4.
(3) Memory map of parameter ROM 6
FIG. 3 is a memory map showing the data stored in the parameter ROM 6. The
parameter ROM has a plurality of storage areas, each one of which has a
storage capacity of 16 bits. In these storage areas, the one hundred
continuous storage areas corresponding to the absolute addresses [0] to
[99] are tone color data areas in which tone color data corresponding to
one hundred kinds of tone colors are stored. These tone color data areas
are followed by waveform sample data areas in which the sample data of the
waveforms corresponding to the tone colors are stored.
Each one of the tone color data areas consists of six storage areas which
are assigned the relational addresses [0] to [5]. The content of the tone
color data stored in these six storage areas are as follows:
In the upper 8 bit area of the storage area corresponding to the relational
address [0], a level shift data LS is stored. In the lower 8 bit area of
the storage area corresponding to the relational address [0], the upper 8
bit of a start address SAH is stored. In the upper 8 bit area of the
storage area corresponding to the relational address [1], the middle 8 bit
of the start address SAM is stored. In the lower 8 bit area of the storage
area corresponding to the relational address [1], the lower 8 bit of the
start address SAL is stored. These data SAH, SAM and SAL constitute a 24
bit start address which is the absolute address of the storage area in
which the leading sample data of the waveform of the corresponding tone
color is stored. In the upper 8 bit area of the storage area corresponding
to the relational address [2], the upper 8 bit of a loop start address LSH
is stored and in the lower 8 bit area, the lower 8 bit of the loop start
address LSL is stored. These data LSH and LSL constitute a 16 bit loop
start address LS which designates the starting point of the loop
regeneration part of the waveform sampling data which are to be repeatedly
regenerated are stored. The loop start address LS is defined as the
relational address with respect to the start address SA=SAH+SAM+SAL. In
the upper 8 bit area of the storage area corresponding to the relational
address [3], the upper 8 bit of a loop end address LEH is stored and in
the lower 8 bit area, the lower 8 bit of the loop end address LEL is
stored. These data LEH and LEL constitute a 16 bit loop end address LE
which designates the trailing point of the loop regeneration part. The
loop end address LE is defined as the relational address with respect to
the start address SA. FIG. 4 shows the relationship between start address
SA, loop start address LS and loop end address LE. When a note-on command
is given to generate a musical tone having a tone color, the sample data
of the storage area, the absolute address of which is designated by the
start address SA corresponding to the tone color, is read out at first,
after which the sampling data of the following storage are sequentially
read out. After the sample data is read out from the storage area, the
relational address of which is designated by the loop end address LE
corresponding to the tone color, the sample data of the loop regeneration
part are repeatedly read out from the storage areas, the relational
address of the starting point of which is LS and the relational address of
the ending point of which is LE.
In the upper 8 bit area of the storage area corresponding to the relational
address [4], modulation control data MS, AMD and PMD are stored. In the
lower 8 bit area of the storage area corresponding to the relational
address [4] and in the upper 12 bit area of the storage area corresponding
to the relational address [5], the data for controlling the envelope of the
musical tone having the corresponding tone color. More specifically, in the
lower 4 bit area of the storage area corresponding to the relational
address [4], attack rate AR which determines the variation in time of the
attack part of the envelope of the musical tone to be generated and the
first decay rate D1R which determines the variation in time of the first
decay part D1 of the envelope are stored. Next, in the upper 12 bit area
of the storage area corresponding to the relational address [5], the
second decay ratio D2R which determines the variation in time of the
second decay part D2 of the envelope of the musical tone to be generated
and release rate RR which determines the variation in time of the release
part R of the envelope and reference level DL which designates the level
of the envelope at which the part of the envelope is changed from the
first decay part to the second decay part (see FIG. 5). Next, in the lower
4 bit area of the storage area corresponding to the relational address [5],
key-scaling coefficient KS is stored.
(4) Memory map of common RAM 7
FIG. 6 is a memory map showing the musical tone parameter storage areas
provided in common RAM 7. Common RAM 7 consists of a plurality of storage
areas, each one of which has a storage capacity of 8 bit. In these storage
areas, a continuous storage areas, the leading storage area of which has
the absolute address of [0], are sound channel data areas for storing
musical tone parameters corresponding to the sound channels CHi (i=0 to
11). The sound channel data areas are followed by work areas consists of a
series of storage areas in which control data used by CPU 11 are stored.
Each one of the sound channel data areas consists of twelve storage areas
to which the relational addresses [0] to [11] are assigned. The
description for these twelve storage areas will be given as follows:
The storage area corresponding to the relational address [0] is used for
storing the lower 8 bit data VnL of the voice number VnL which designates
the tone color of the musical tone to be generated at the corresponding
sound channel. Next, in the storage area corresponding to the relational
address [1], the upper 6 bit area is used for storing the lower 6 bit data
FnL of F number Fn which designates the tone pitch of the musical tone to
be generated at the corresponding sound channel and the lower 2 bit area
is used for storing the upper 2 bit data VnH of the voice number Vn. Next,
in the storage area corresponding to the relational address [2], the upper
4 bit area is used for storing octave data Oct which designates the octave
of the musical tone to be generated and the lower 4 bit area is used for
storing the upper 4 bit data FnH of the F number. Next, in the storage
area corresponding to the relational address [3], the upper 2 bit area is
used for storing note-on flag NON which triggers the musical tone
generation and the middle 2 bit area is used for storing sustain data SUS
which designates the actuated amount of the sustain pedal (the
illustration is omitted) and the remaining lower 4 bit area is used for
storing sound image position data PAN.
The above-described data VnL, FnL, VnH, Oct, FnH, NON, SUS and PAN are
generated by CPU 11 and are thereby written in the corresponding storage
areas. More specifically, when a key of keyboard 1 is depressed, data VnL,
FnL, VnH, Oct, FnH, SUS and PAN are determined by CPU 11 based on the
key-on event of the depressed key and the status of the operational
members such as tone color designating switches (the illustration is
omitted), and the sound channel to be assigned for the tone generation of
the musical tone corresponding to the key-on event is determined, and
after which the above determined data are written in the sound channel
data area corresponding to the sound channel thus determined. Furthermore,
data "1" is written in the sound channel data area as note-on flag NON.
When the key previously depressed is released, the sound channel which is
assigned for generating the musical tone corresponding to the released key
is searched by CPU 11, after which data "0" is written as note-on flag NON
in the sound channel data area corresponding to the sound channel thus
searched.
Next, the storage area corresponding to the relational address [4] is used
for storing total level data TL. Next, in the storage area corresponding
to the relational address [5], the upper 4 bit area is used for storing
attack rate AR and the lower 4 bit area is used for storing the first
decay rate D1R. Next, in the storage area corresponding to the relational
address [5], the upper 4 bit area is used for storing attack rate AR and
the lower 4 bit area is used for storing the first decay rate D1R. Next,
in the storage area corresponding to the relational address [6], the upper
4 bit area is used for storing the second decay rate D2R and the lower 4
bit area is used for storing release rate RR. Next, in the storage area
corresponding to the relational address [7], the upper 4 bit area is used
for storing reference level DL and the lower 4 bit area is used for
storing key-scaling coefficient KS. Next, the storage area corresponding
to the relational address [8] is used for storing modulation control data
MS, AMD and PMD. Next, in the storage area corresponding to the relational
address [9], the upper 4 bit area is not used and the lower 4 bit area is
used for storing shift data LS.
The above-described data TL, AR, D1R, D2R, RR, DL, KS, MS, AMD, PMD and LS
are generated by tone generator 5 and are thereby written in the
corresponding storage areas. Thus, when a key-on event is detected and
voice number Vn of the musical tone to be generated is then written by CPU
11 in one of the sound channel data area, the tone color data TL, AR, D1R,
D2R, RR, DL, KS, MS, AMD, PMD and LS which correspond to the voice number
are read out from parameter ROM 6 by tone generator 5, after which the
read out tone color data are written in the above sound channel data area.
When the key-off event corresponding to the above key-on event is detected
and data "0" is written as note-on flag NON in the above sound channel
data area, release rate RR having a large value is written in the above
sound channel data area by tone generator 5.
Next, the storage area corresponding to the relational address [10] is used
for storing the upper 8 bit data EGH of current envelope data EGD. Next, in
the storage area corresponding to the relational address [11], the upper 2
bit area is used for storing the lower 2 bit data EGL of the current
envelope data EGD and the following middle 2 bit area is used for storing
current state data EGS and the remaining lower 4 bit data is not used. The
current envelope data EGD indicates the value of the envelope which is
currently being generated by tone generator 5. The current state data EGS
indicates the state of the envelope currently being generated. These data
are written in common RAM 7 by tone generator 5.
(5) Configuration of tone generator 5
The tone generator 5 consists of a tone generating section 51 which
generates the left and right channels musical tone signals; a note-on
pulse generator 52; a TG (tone generator) address generator 53; and a TG
data bus GEB which connects these elements 51 to 53 together.
The tone generating section 51 carries out the following operations (a) to
with respect to each sound channel to generate the left and right channels
musical tone signals LOUT and ROUT corresponding to the sound channel:
(a) When a load signal LOAD is set to "1" by write operation detecting
section 9, reading out voice number Vn from the sound channel data area of
common RAM 7, which corresponds to the current sound channel (i.e., the
sound channel which is assigned for the tone generation).
(b) Reading out the tone color data from the tone color data area of
parameter ROM 9, which corresponds to the voice number Vn obtained by the
operation a), and writing the tone color data in the sound channel data
area of common RAM 7, which corresponds to the above sound channel which
is assigned for the tone generation. Furthermore, outputting a load number
LN, when the above reading and writing operation for the tone color data
are carried out.
This load number LN is sequentially changed from [0] to [5] during the six
sampling periods after the load signal LOAD is changed to "1". The load
number LN is used for the relational address for designating the tone
color data to be read out from parameter ROM 6 and is also used for
calculating the relational address which designates the storage area of
the sound channel data area in which the tone color data read out from
parameter ROM 6 is to be written. The load number LN is generated by
address generator 502 (this will be described later) of tone generating
section 51.
(c) Using the sound channel data area of common RAM 7 as storing means for
storing the envelope data and sequentially calculating the envelope data
of the musical tone to be generated.
(d) Sequentially reading out the waveform sample data corresponding to the
voice number Vn from parameter ROM 6 during the above operation (c) and
carrying out a manufacture on the waveform sample data based on the tone
color data corresponding to the voice number Vn to generate musical tone
signals LOUT and ROUT.
Hereinafter, the operation mode in which the above operations (a) and (b)
are carried out will be called as a load mode, while the operation mode in
which the above operations (c) and (d) are carried out will be called as a
sound mode.
The note-on pulse generator 52 observes the note-on flags NON of the all
sound channels. When the note-on flag NON of one of the sound channels is
changed to "1", note-on pulse generator 52 supplies a note-on signal NONS
to tone generating section 51 at the timing corresponding to the sound
channel.
Tne TG address generator 53 sequentially supplies the address data
ADR.sub.G, the contents of which are shown in the following table-1, in
each time slot of every sound channels. In the table-1, i designates the
current sound channel number. Furthermore, the addresses generated in time
slots T.sub.3, T.sub.8, T.sub.11 and T.sub.14 are write addresses, while
the addresses generated in the other time slots are read addresses.
Furthermore, A.sub.x and A.sub.y designate the relational addresses which
are determined based on the above-described load number LN as if LN=[0]
then Ax=[9], and if LN=[4] then Ax=[8] and Ay=[5], and if LN=[5] then
Ax=[6] and Ay=[7].
TABLE 1
______________________________________
TG-address ADR.sub.G in each time slot
______________________________________
time slot T0: 6(i - 1) + 1
time slot T1: 6(i - 1) + 2
time slot T2: 6(i - 4) + 3
time slot T3: 6(i - 3) + Ax
time slot T4: 6(i - 3) + 4
time slot T5: 6(i - 3) + 5
time slot T6: 6(i - 3) + 6
time slot T7: 6(i - 3) + 7
time slot T8: 6(i - 3) + Ay
time slot T9: 6i + 8
time slot T10: 6(i - 3) + 9
time slot T11: 6(i - 4) + 10
time slot T12: 6(i - 3) + 10
time slot T13: 6(i - 3) + 11
time slot T14: 6(i - 4) + 11
time slot T15: 6i
______________________________________
In the above formulae, in the case where the value of first item 6(i-k) is
a minus value, 6(i-k+12) is used as the first Item of the formula instead
of 6(i-k). The first items of the above formulae designate the leading
addresses of the sound channel data areas in which the data to be read out
for the tone generation of the corresponding sound channels are stored,
while the second items of the above formulae designate the relative
addresses of the data with respect to the addresses of the leading data.
In addition, the TG address generator 53 generates the first and second
write control signals GW and GWa, which are necessary for the access
control of common RAM 7, and supplies them to RAM access control section
8. The description for the write control signals will be given later.
The elements of tone generator 5 are connected together via TG data bus GEB
which consists of the 0th to the 7th bit lines.
(5a) Configuration of tone generating section 51
Next, the configuration of tone generating section 51 will be described
with reference to FIG. 7.
Latches 701 to 717 respectively latch the data of the corresponding bit
lines of TG data bus GEB at the predetermined time slots. In FIG. 7, one
of the symbols T1 (i=0 to 15) is written in each one of the boxes which
indicate latches 701 to 717. These symbols indicate the time slots at
which the corresponding latches latch the data from TG data bus GEB.
Address register section 501 consists of a 24 bit | | |
