Data transmission system selecting both source and destination using addressing mechanism

A data transmission system includes a main controlling unit for producing pieces of address information, each piece of address information being indicative of a first address for a data source and a second address for a destination. The data transmission system further includes a plurality of component units assigned individual addresses, respectively, and a timing controlling unit sequentially supplying the pieces of address information to the component units at predetermined timings. In operation, one of the component units with the individual address matched with the first address serves as the data source and another component unit with the individual address matched with the second address serves as the destination communicating with the data source.

FIELD OF THE INVENTION 
This invention relates to a data transmission system and, more 
particularly, to a high-speed data transmission system shared between a 
plurality of data sources. 
DESCRIPTION OF THE RELATED ART 
Various data transmission systems have been proposed for digital data 
transmission, and FIG. 1 shows one of the data transmission systems for 
serial data. The data transmission system has a serial data bus group A0 
to An, another serial data bus group B1 to Bn and a matrix switching 
network 1 selectively providing interconnections therebetween. 
In some general purpose computer systems is employed a data transmission 
system which is called as "VME bus" corresponding to 821 bus of the 
International Electrotechnical Commission (IEC) standard and to P1014/D1.2 
of the International Society of Electrical and Electronic Engineers (IEEE) 
standard. The Virtual Machine Environment (VME) bus system directly 
interconnects component boards and is of an asynchronous communication 
system. In the asynchronous communication system, the data source unit 
needs to wait until receipt of acknowledgment indicative of completion of 
the data transmission supplied from the destination, but the system can 
propagate various data formats. 
However, the first data transmission system fabricated with the matrix 
switching network I inherently suffers from a low speed, and a large 
number of bus lines make the matrix switching network complex. Such a 
complex matrix switching network is so expensive that the data 
transmission system is not desirable in view of the production cost of a 
computer system. 
The data transmission timing VME is uncertain in the VME bus system and is, 
therefore, ineligible for a real time processing such as, for example, an 
audio message. If the VME bus system is used for the real time processing 
accompanied with a transmission of digital sound data, the sound data need 
to be rearranged along the lapse of time, and, therefore, an additional 
software is necessary for a retrieval of the real sound. This results in 
that the total load of a central processing unit is increased, and the VME 
bus system is uneconomical in such a real time processing. 
SUMMARY OF THE INVENTION 
It is therefore an important object of the present invention to provide a 
data transmission system which is responsive to a high speed serial data 
transmission. 
It is also an important object of the present invention to provide a timing 
controlling unit which is incorporated in the data transmission system for 
the high speed serial data transmission. 
In accordance with one aspect of the present invention, there is provided a 
data transmission system comprising a) a main controlling unit for 
producing pieces of address information, each piece of address information 
being indicative of a first address for a data source and a second address 
for a destination, b) a plurality of component units assigned individual 
addresses, respectively, and having respective data storages, and c) a 
timing controlling unit storing the pieces of address information and 
sequentially supplying the pieces of address information to the component 
units at predetermined timings, in which one of the component units with 
the individual address matched with the first address serves as the data 
source and in which another component unit with the individual address 
matched with the second address serves as the destination communicating 
with the data source. 
In accordance with another aspect of the present invention, there is 
provided a timing generating unit provided in association with data 
rewriting means for producing pieces of address information each 
indicative of a first address of a data source and a second address of a 
destination; the pieces of address information being grouped into at least 
first and second groups, comprising: a) a first memory unit alternatively 
entering a write-in mode and a read-out mode of operation and storing the 
pieces of address information of one of the first and second groups in a 
rewriteable manner; b) a second memory unit alternatively entering a 
write-in mode and a read-out mode of operation and storing the pieces of 
address information of the other of the first and second groups in a 
rewriteable manner; c) address information generating means for 
sequentially producing a series of memory addresses for the read-out mode 
of operation; and d) switching means coupled at one end thereof to the 
first and second memory units and at the other ends thereof to the data 
rewritting means and the address information generating means and allowing 
one of the first and second memory units to enter the write-in mode of 
operation for storing the pieces of address information fed from the data 
rewriting means, the switching means further allowing the other of the 
first and second memory units to enter the read-out mode of operation for 
sequentially delivering the pieces of address information in the presence 
of the memory addresses.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
First Embodiment 
Referring first to FIG. 2 of the drawings, a data transmission system 
embodying the present invention largely comprises a main controlling unit 
21, a timing controlling unit 22 and two component units 23 and 24 
communicable with one another through a data bus 25 under the control of 
the timing controlling unit 22. Although more than two component units are 
coupled to the data bus 25, only two component units 23 and 24 are shown 
in FIG. 2 for the sake of simplicity. In the following description, the 
component unit 23 behaves as a data source, and the component unit 24 
serves as a destination. 
The main controlling unit 21 produces pieces of address information and 
supplies a multi-bit address signal indicative of each piece of address 
information to the timing controlling unit 22. The multi-bit address 
signal is formed into a data format including a first section occupied by 
a first address of a data source and a second section occupied by a second 
address of a destination. A series of the multi-bit address signals are 
sequentially supplied from the main controlling unit 21 to the timing 
controlling unit 22 and form an address queue in the timing controlling 
unit 22. While new multi-bit address signals enter the address queue, the 
multi-bit address signals previously supplied are sequentially read out 
from the address queue and supplied to the component units including the 
units 23 and 24 at predetermined time intervals. Whenever the first and 
second sections of the multi-bit address signal designate the component 
units 23 and 24 as the data source and the destination, respectively, and 
data are transmitted from the component unit 23 to the component unit 24. 
Since the multi-bit address signals are managed to be sequentially 
released from the address queue at predetermined timings, the data 
transmission is repeated at a high speed, and a large amount of data 
information is transmitted from the data source to the destination in 
synchronization with another processing. Namely, if the timing controlling 
unit 21 repeats the designation of the component units 23 and 24 take 
place, the data transmission is carried out at a high speed. If, on the 
other hand, the designation of the component units 23 and 24 takes place 
at a predetermined time interval adjusted to a time duration of a 
periodical data processing, the data transmission is carried out in 
synchronization with the periodical data processing, and, accordingly, the 
subsequent stage is given on a real time basis. 
Turning to FIG. 3 of the drawings, the timing controlling unit 22 comprises 
a first memory unit 22a having a plurality of memory locations 
respectively assigned addresses, a second memory unit 22b having a 
plurality of memory locations respectively assigned addresses, address 
information generating means 22c operative to produce an address signal 
indicative of one of the addresses and increment the address, and 
switching means for alternately coupling the memory units 22a and 22b to 
the address information generating means 22c. The first and second memory 
units 22a and 22b are further coupled to data rewriting means 23 for 
selectively supplying new data to one of the memory units 22a and 22b. The 
data rewriting means may be implemented by the main controlling unit 21, 
and the address queue is formed in the first and second memory units 22a 
and 22b. 
The timing controlling unit 22 thus arranged behaves as follows. While data 
bits in one of the memory units 22a and 22b are rewritten by the data 
rewriting means, the other memory unit is supplied with the address signal 
sequentially incremented and data bits are read out therefrom. The data 
bits thus sequentially read out are formed into the multi-bit address 
signal having the first and second sections, and two of the component 
units are designated as a data source and a destination. Since the address 
information generating means 22c and the data rewriting means are 
alternately coupled to the first and second memory units 22a and 22b, the 
timing controlling unit 22 can successively supply the multi-bit address 
signals to the component units while receiving new multi-bit address 
signals. 
Description is hereinbelow made on a sound synthesizing system which has 
the data transmission system shown in FIG. 2. FIG. 4 shows the arrangement 
of the sound synthesizing system comprising an analog-to-digital 
converting module 41 coupled to a microphone unit 41a and having an 
interface 41b, a waveform memory module 42 having an interface 42a, a 
digital-to-analog converting module 43 having an interface 43a and coupled 
to a sound system 43b associated with a loud speaker system 43c, and a DSP 
(Digital Signal Processor) module 44 having an interface 44a and a random 
access memory 44b. A control bus 45, a data bus 46 and an address bus 47 
are shared between those modules 41 to 44, and predetermined individual 
addresses are assigned the modules 41 to 44, respectively. The bus 
controller 48 activates one of the modules 41 to 44 as a data source and 
another module as a destination. Namely, when the bus controller 48 
supplies the address bus 47 an address signal Sa representative of first 
and second addresses of the data source and the destination in 
synchronization with a timing signal TG, two of the modules 41 to 44 
acknowledge the designation of the data source and the destination with 
the first and second addresses and a data transmission is carried out 
therebetween through the data bus 46. Thus, the bus controller 48 manages 
the occupation of the data bus 46 and, therefore, serves as the timing 
controlling unit 22 shown in FIGS. 2 and 3. In this instance, the modules 
41 to 44 are equivalent to the component units including the units 23 and 
24. 
The bus controller 48 is coupled to a main controlling unit 49 which is 
associated with a keyboard 49a and a manipulating panel 49b. The keyboard 
49a produces a various performance signals S1 on the basis of a 
performance by a player or an automatic performance by an automatic 
performance system, and each of the musical signals is indicative of a 
piece of musical information. On the manipulating panel 49b are arranged a 
plurality of switching elements each producing an instruction signal S2 
indicative of a user's instruction such as selecting a tone color. The 
main controlling unit 49 has a central processing unit (not shown) as well 
as memory unit (not shown) and not only directly controls the modules 41 
to 44 but also supervises the data transmission therebetween with the bus 
controller 48. 
The modules 41 to 44 respectively achieve predetermined tasks, and 
description is briefly made on those tasks:. The microphone unit 41a 
changes a sound into an analog electric sound signal Sv1 and supplies it 
to the analog-to-digital converting unit 41, and the analog-to-digital 
converting unit 41 samples the analog electric sound signal Sv1 at 
predetermined time intervals, then the sampled discrete voltage levels are 
sequentially converted into a series of digital sound signals Sd1. The 
digital sound signals Sd1 are supplied to the data bus 46 upon designation 
with the address signal Sa. The waveform memory module 42 can memorize the 
digital sound signals Sd1 inputted from the data bus 42 so that various 
waveforms inherent to musical instruments such as, for example, a piano, a 
harpsicord and so forth can be memorized in the waveform memory module 42, 
and each waveform is retrieved depending upon the performance signal S1. 
The digital-to-analog converting module 43 is supplied with the digital 
sound signals Sd1 and converts them to the analog electric sound signal 
Sd1, then supplying the analog electric sound signal Sd1 to the sound 
system 43b. The sound system 43b increases the analog electric sound 
signal Sd1 in magnitude and, then, supplies the analog electric sound 
signal Sd1 thus amplified to the loud speaker system 43c. The DSP module 
44 receives the digital sound signal Sd1 and executes digital operations 
for modifying waveform, mixing waveforms, adding reverberation, chorus 
effect, vibrato effect and so on. Thus, the DSP module 44 serves as a 
mixer, equalizer and some effecters. 
The bus controller 48 is illustrated in detail in FIG. 5 of the drawings. 
The bus controller 48 is coupled to the main controlling unit 49 and 
supplies the timing signal TG and the address signal Sa to the control bus 
45 and the address bus 47, respectively. The bus controller 48 comprises a 
first random access memory unit 48a and a second random access memory unit 
48b, and each of the random access memory units 48a and 48b has an address 
port (abbreviated as "ADD" ) supplied with an address signal Sam 
indicative of a memory address of either random access memory unit 48a or 
48b, a data port (designated by "DATA"), a chip select terminal and a 
write-in enable terminal. The random access memory unit 48a or 48b is 
activated in the presence of a chip select signal of an active low level 
supplied to the chip select terminal. If a write-in enable signal of an 
inactive high level is supplied to the write-in enable terminal, data bits 
are read out from a memory cell groups indicated by an address signal Sam 
fed to the address port of the activated memory unit 48a or 48b and 
supplied the data port thereof; however, new data bits supplied to the 
data port are written into a memory cell group indicated by the address 
signal Sam in the presence of the write-in enable signal of the active low 
level. If the chip select signal remains in the inactive high level, the 
data port enters a high-impedance state, and, therefore, no communication 
is established between the memory cells and an external unit or circuit. 
The bus controller 48 further comprises first and second switching units 
48c and 48d each having a plurality of switching elements, and the first 
and second switching units 48c and 48d are responsive to a controlling 
signal Sr fed from a random access memory (RAM) controlling circuit 48e. 
Namely, if the first and second switching units 48c and 48d are changed to 
the state shown in FIG. 5, the first switching unit 48c allows the main 
controlling unit 49 to rewrite the data bits stored in the first random 
access memory unit 48a freely. However, since the second random access 
memory unit 48b is supplied at the chip select terminal with the active 
low level and at the write-in control terminal with the inactive high 
voltage level, the second random access memory unit 48b is allowed 
read-out operation only. Responsive to the address signal Sam fed from a 
counter circuit 48f and the address signal Sam is indicative of the memory 
address and sequentially incremented by clock signal Sc1 fed from a timing 
generating circuit 48g, the second random access memory unit 48b provides 
data bits to the output port thereof, and the data bits are indicative of 
the first and second addresses of the data source and the destination. The 
second switching unit 48d relays the data bits thus read out to a 
tri-state buffer circuit 48h which in turn transfers the data bits to the 
address bus 47 as the address signal Sa indicative of the first address 
and the second address. 
If, on the other hand, the first and second switching units 48c and 48d are 
changed from the states shown in FIG. 5 to the opposite states or all of 
the switching elements of the units 48c and 48d provide respective signal 
paths to the other contacts, the second random access memory unit 48b is 
communicable with the main controlling unit 49, and the first random 
access memory unit 48a supplies the data bits rewritten by the main 
controlling unit 49 to the address bus 47 in synchronization with the 
address signal Sam fed from the counter circuit 48f. 
As described hereinbefore, the timing generating circuit 48g supplies the 
clock signal Sc1 to the counter circuit 48f for incrementing the memory 
address. The timing generating circuit 48g is further operative to define 
a series of time slots. Namely, a system clock signal CL is supplied to 
the timing generating circuit 48g, and the timing generating circuit 48g 
produces a time slot controlling signal St (which forms a part of the 
timing signal TG in FIG. 3) on the basis of the system clock signal CL. 
The time slot controlling signal St is fed through a buffer circuit 48i to 
the control bus 45, and each time slot starts with the time slot 
controlling signal St. Each time slot is defined as "a unit of time 
interval for a single data transmission" carried out in the sound 
synthesizing system shown in FIG. 4. Each module 41, 42, 43 or 44 is 
responsive to the time slot controlling signal St and occupies the data 
bus 46 over the single time slot for a data transmission. The time slot 
controlling signal St is further supplied to the tri-state buffer circuit 
48h for synchronous operation between the time slot and the address signal 
Sa. Detailed description will be made hereinlater. 
Since the clock signal Sc1 is delivered at every time slot,, the counter 
circuit 48f is incremented in synchronization with the time slot. The 
counter circuit 48f starts at value "0" and increases the value to "N". 
When the value reaches "N", the counter circuit 48f returns to value "0" 
and repeats the counting operation between values "0" and "N". Each value 
from "0" to "N" is indicative of the memory address assigned to a group of 
the memory cells incorporated in either random access memory unit 48a or 
48b, and, therefore, the address signal Sam circulates between the address 
"0" and the address "N". Upon returning to value "0" the counter circuit 
48f produces a sampling timing signal Sp which is transferred through a 
buffer circuit 48j to the control bus 45 for defining a single sampling 
time period. The sampling time period consists of "N+1" time slots and is 
occupied by a single transfer operation consisting of a plurality of the 
data transmissions. In this instance, the sampling timing signal Sp 
further defines a single sampling operation for the analog electric sound 
signal Sv1, and, therefore, the data transfer operation is equivalent in 
time length to the single sampling operation for the analog electric sound 
signal Sv1. Detailed description will be hereinlater made. 
The sampling timing signal Sp is further supplied to the RAM controlling 
circuit 48e, and the RAM controlling circuit 48e supplies the controlling 
signal Sr to the first and second switching units 48c and 48d in the 
presence of the sampling timing signal Sp. With the controlling signal Sr, 
the first and second switching units 48a and 48b changes the signal paths 
between aforementioned two different states, and the first and second 
random access memory units 48a and 48b are alternatively coupled to the 
main controlling unit 49 and the address bus 47. In other words, while one 
of the first and second random access memory units 48a and 48b is 
rewritten by the main controlling unit 49 over a single sampling period, 
the other random access memory unit delivers the data bits to the address 
bus 47 in synchronization with the address signal Sam fed from the counter 
circuit 48f. Thus, the RAM controlling circuit 48e controls the 
alternative operations witch the controlling signal Sr. The controlling 
signal Sr is never delivered from the RAM controlling circuit 48e on the 
way to the termination of a sampling time period. The controlling signal 
Sr is delivered at completion of a sampling period only. 
In this instance, the first and second random access memory units 48a and 
48b serve as the first and second memory units 22a and 22b, the first and 
second switching units 48c and 48d and the RAM controlling circuit 48e 
form in combination the switching means 22d, and the timing generating 
circuit 48g and the counter circuit 48f as a whole constitute the address 
information generating means 22c. 
Description is made on the behavior of the sound synthesizing system in 
detail. First, the RAM controlling circuit 48e is assumed to change the 
first and second switching units 48a and 48b to the states shown in FIG. 5 
with the controlling signal Sr. In this situation, the counter circuit 48f 
returns to value "0", and a sampling time period restarts in the presence 
of the sampling timing signal Sp. The main controlling unit 49 allows the 
chip select signal and the write-in enable signal to go down to the active 
low levels, respectively, and respectively supplies the address signal Sam 
and the data bits to the address port and the data port of the first 
random access memory unit 48a. The address signal Sam is incremented from 
address "0" to address "N", and the data bits are rewritten in 
synchronization with the address. Then, a plurality of new data bit groups 
are written into the first random access memory unit 48a by the main 
controlling unit 49, and each data bit group provides addresses assigned 
two of the modules 41 to 44 which occupies the data bus 46 over a single 
time slot as the data source and the destination. When the write-in 
operation is completed, the first random access memory unit 48a maintains 
pieces of address information each indicative of the first and second 
addresses used in the next sampling period. While the write-in operation 
is carried out, a plurality of data bit groups are sequentially read out 
from the second random access memory unit 48b in synchronization with the 
address signal Sam fed from the counter circuit 48f. 
When the counter circuit 48f reaches the value "N" and returns to "0", the 
sampling timing signal Sp is fed from the counter circuit 48f to not only 
the control bus 45 but also the RAM controlling circuit 48e. The RAM 
controlling circuit 48e change the first and second switching units 48c 
and 48d so that the first random access memory unit 48a is coupled to the 
address bus 47 through the second switching unit 48d and the tri-state 
buffer circuit 48d. Since the chip select terminal and the write-in enable 
terminal of the first random access memory unit 48a are supplied with the 
active low level and the inactive high level, respectively, the first 
random access memory unit 48a is responsive to the address signal Sam fed 
from the counter circuit 48f for a read-out operation. First, the address 
signal Sam indicative of the address "0" is fed to the address port of the 
first random access memory unit 48a, and the first data bit group is read 
out from the memory cells assigned the address "0" to the data port. The 
data bit group thus read out to the data port is representative of the 
first and second addresses identical with two individual addresses 
assigned the modules 41 to 44, and the address signal Sa indicative of the 
first and second addresses is supplied from the tri-state buffer circuit 
48h to the address bus 47 in synchronization with the time slot 
controlling signal St serving as the timing signal TG. The counter circuit 
48f increments the memory address indicated by the address signal Sam, and 
the second data bit group is read out from the first random access memory 
unit 48a. The second data bit group is also indicative of two individual 
addresses of the modules designated as the next data source and the next 
destination, and the next address signal Sa is fed from the tri-state 
buffer circuit 48h to the address bus 47 in synchronization with the time 
slot controlling signal St. Thus, the data bit groups are sequentially 
read out from the first random access memory unit 48a, and the address 
signals Sa successively propagate on the address bus 47 for controlling 
the data transmissions. While the first random access memory unit 48a 
provides a series of the address groups to the modules 41 to 44, the main 
controlling unit 49 rewrites the data bits in the second random access 
memory unit 48b. The RAM controlling circuit 48e allows the main 
controlling unit 49 and the RAM controlling circuit 48e to alternately 
rewrite and read out the data bit groups memorized in the first and second 
random access memory units 48a and 48b, and, therefore, the bus controller 
48 sequentially designates two of the modules 41 to 44 as the data source 
and the destination for data transmission. 
Each of the modules 41 to 44 monitors the address signal Sa to see whether 
or not the bus controller 48 designates as a data source or a destination. 
If one of the modules 41 to 44 acknowledges itself as the data source or 
the destination, the designated module 41, 42, 43 or 44 participates the 
data transmission under the supervision of the bus controller 48. 
The data transmission is described in detail with reference to FIG. 6 of 
the drawings. Assuming now that the pieces of address information are in 
the address queue Qa produced in the bus controller 48, every block in the 
upper row Qa1 is paired with the corresponding block in the lower row Qa2, 
and each block pair indicates the piece of address information. Each piece 
of address information is indicative of a first address of a data source 
61 (represented by the block in the upper row Qa1) and a second address of 
a destination 62 (represented by the block in the lower row Qa2), and the 
first and second addresses are represented by the data bits or the data 
bit group memorized in either first or second random access memory unit 
48a or 48b. In the following description, one of the analog-to-digital 
converting module 41, the waveform memory module 42 and the digital signal 
processor (DSP) module 44 is designated as the data source, and one of the 
digital-to-analog converting module 43, the waveform memory module 42 and 
the DSP module 44 serves as the destination. 
When the sequential read-out operation reaches the hatched blocks in the 
address queue Qa, the piece of address information is read out to the 
address bus 47 and the first and second addresses are respectively 
transferred to the modules 41 and 44 in the time slot "4". The address of 
the data source is distributed to all of the modules 41 to 44, and the 
modules 41 to 44 compares the address of the data source with the 
individual addresses assigned thereto. Only the module serving as the data 
source 61 finds that the first address to be distributed is matched with 
the individual address assigned thereto through the comparison carried out 
by a component comparator 61a, and the component comparator 61a closes a 
component switching element 61b. Then, a data signal indicative of data DS 
to be requested is put on the data bus 46. 
The second address of the destination 62 is also distributed to all of the 
modules 41 to 44 within the same time slot "4" and is compared with the 
individual addresses assigned the respective modules 41 to 44. In another 
module serving as the destination 62, a component comparator 62a allows a 
component switching element 62b to be close upon matching the second 
address of the destination 62 with the individual address to be memorized 
in an address memory 62c. The data signal indicative of the requested data 
DS supplied from the data bus 46 passes through an interface 62d. Thus, 
the bus controller 48 sequentially designates two of the modules 41 to 44 
as the data source 61 and the destination 62 in every time slot and, 
accordingly, allows various data to be transmitted through the single data 
bus 46. 
As described hereinbefore, every sampling time period consists of the time 
slots "0" to "N" and is equal in time length to the sampling operation for 
the analog electric sound signal Sv1. If the data transmission for the 
digital sound signal Sd1 is fixedly assigned to the time slot "4", the 
digital sound signal Sd1 is transmitted from the analog-to-digital 
converting module 41 on a real time basis, and no rearrangement is needed 
for the data to be transmitted after receipt at the destination 62. 
If a large amount of data are requested to be transmitted from the data 
source 61 to the destination 62 at a high speed, a plurality of time slots 
are assigned to the data source 61 and the destination 62 in every 
sampling period. Since the data transmission speed is in proportion to the 
number of the time slots to be assigned in every sampling period, a large 
amount of data are transmitted from the data source 61 to the destination 
62 within a relatively short time period. In other words, the data 
transmission speed is adjustable to an arbitrary level by rearranging the 
pieces of address information in the address queue Qa. Thus, a wide 
variety of operation is carried out by the bus controller 48, and the 
variation is merely achieved by changing the data bits stored in the first 
and second random access memory units 48a and 48b. 
The present invention is further applicable to another system such as, for 
example, an audio recording/reproducing system shown in FIG. 7. The audio 
recording/reproducing system shown comprises an analog-to-digital 
converting module 71, a digital-to-analog converting module 72, a digital 
input-and-output module 73, a DSP module 74, and a disc controlling module 
75 associated with a hard disc 75a. These modules 71 to 75 are 
communicable with one another through a data bus 76, and an address bus 77 
and a control bus 78 are further provided thereto. The data bus 76 is 
under the control of a bus controller 79 coupled to a main controlling 
unit 80, and instructions are provided to the main controlling unit 80 
through a manipulating panel 80a. The hard disc 75a is under the 
supervision of the disc controlling module 75, and digital data are 
written into and retrieved from the hard disc 75a. Since the audio 
recording/reproducing system shown in FIG. 7 is equipped with the digital 
input-output module 73, the system is extensible to another digital sound 
system 73a. Other component modules and units are similar to those 
incorporated in the sound synthesizing system shown in FIG. 4, and no 
further description is incorporated for the sake of simplicity. 
The bus controller 79 behaves as similar to the bus controller 48, and a 
high speed data transmission and a synchronous data transmission are 
achieved by arranging the pieces of address information in an address 
queue formed therein. 
Second Embodiment 
Turning to FIG. 8 of the drawings, another data transmission system 
embodying the present invention largely comprises a main controlling unit 
91 for sequentially producing pieces of address information, a timing 
controlling unit 92 supplied from the main controlling unit 91 with the 
pieces of address information and memorizing the pieces of address 
information in an address queue established therein, and a plurality of 
component units including component units 93, 94 and 95 sequentially 
supplied from the timing controlling unit 92 with the piece of address 
information at every predetermined timing and transmitting a data signal 
therebetween through a data bus 96. 
In this instance, the component units selectively enter a single data 
transmission mode of operation and a broadcasting mode of operation. In 
detail, each of the pieces of address information has a first address 
indicative of a data source and a second address indicative of a 
destination. The destination is formed by one of the component units 93 to 
95 in the single data transmission mode of operation but is constituted by 
a plurality of component units such as, for example, the component units 
94 and 95 in the broadcasting mode of operation. Either single data 
transmission mode or broadcasting mode of operation is designated by each 
of the pieces of address information. 
If the main controlling unit 91 cyclically produces a predetermined number 
of the pieces of address information and supplies to the timing 
controlling unit, data transmission is periodically carried out from one 
of the component units designated as the data source to another component 
unit designated as the destination in the single data transmission mode of 
operation. The predetermined number of the pieces of address information 
are hereinbelow referred to as "address cycle". If one of or a plurality 
of pieces of address information in each address cycle request one of the 
component units such as the unit 93 to enter the broadcasting mode of 
operation, a data signal is concurrently transmitted from the component 
unit 93 to a destination constituted by a plurality of component units 
such as the component units 94 and 95, and the broadcasting mode of 
operation enhances the data transmission rate of the data bus 96. 
FIG. 9 illustrates a sound synthesizing system where the data transmission 
system shown in FIG. 8 is implemented. The sound synthesizing system shown 
in FIG. 9 comprises an analog-to-digital converting module 101 associated 
with a microphone 101a and having an interface 101b, a waveform memory 
module 102 with an interface 102a, a digital-to-analog converting module 
103 with an interface 103a and coupled to a sound system 103b, and a DSP 
module 104 with an interface 104a and a random access memory 104b, and 
these modules 101 to 104 serving as the component units including the 
units 93 to 95. The sound synthesizing system further comprises a bus 
controller 105, a main controlling unit 106 and a combined unit 107 of a 
keyboard and a manipulating panel, and a control bus 108, a data bus 109 
and an address bus 110 selectively interconnect the component modules and 
units 101 to 107; however, the modules 101 to 104 and the component units 
105 to 107 achieve similar tasks to those of the first embodiment, and, 
for this reason, no further description is incorporated hereinbelow for 
avoiding repetition. Moreover, various control signal lines are also 
omitted from FIG. 9 for the sake of simplicity. 
The bus controller 105 is similar in arrangement to the bus controller 
shown in FIG. 5, and each of the modules 101 to 104 is slightly different 
from the modules 41 to 44 so as to cope with not only the single data 
transmission mode of operation but also the broadcasting mode of operation 
as described hereinbelow. Namely, each piece of address information 
supplied from the main controlling unit 106 to the bus controller 105 is 
carried on a multi-bit address signal ADD, and the multi-bit address 
signal ADD is formatted as shown in FIG. 10. Each column 0c, 1c, 2c, 3c, . 
. . consisting of three blocks represents the multi-bit address signal ADD 
and enters an address queue 120. The uppermost block stands for a first 
address of a data source 121, the middle block indicates a second address 
of a destination 122, and the lowermost block is representative of a mode 
of operation, i.e. either single data transmission or broadcasting mode of 
operation. If the lowermost block is value "1", the single data 
transmission mode of operation is designated; however, the data source 121 
and the destination 122 selected from the data component modules 101 to 
104 enter the broadcasting mode of operation in the presence of the 
lowermost block of value "0". The analog-to-digital converting module 101, 
the waveform memory module 102 and the DSP module 104 are candidates of 
the data source 121, and the destination 122 is selected from the 
digital-to-analog converting module 103, the waveform memory module 102 
and the DSP module 104. In the single data transmission mode of operation, 
the destination 122 consists of a single module selected from the modules 
101 to 104, but a plurality of modules selected from the modules 101 to 
104 constitute the destination 122 in the broadcasting mode of operation. 
All of the modules 101 to 104 are supplied with the address through the 
address bus 110, and a single data transmission is carried out from the 
module designated as the data source 121 to the module designated as the 
destination 122 through the data bus 109. Individual addresses have been 
assigned to the modules 101 to 104, and comparators 121a and 122a compare 
the individual addresses with the first and second addresses, 
respectively. 
Description is firstly made on the single data transmission mode of 
operation with reference to FIG. 10 of the drawings. The address signals 
ADD are sequentially produced by the main controlling unit 106 and 
supplied to the bus controller 105. The address signals ADD successively 
enter the address queue 120 and sequentially read out from the queue 120 
to the address bus 110 at every predetermined timings. The predetermined 
timings respectively define time slots, and a predetermined number (N+1) 
of the time slots constitute a single sampling time period. In this 
instance, the sampling time period is as long as a sampling cycle for an 
analog electric sound signal Sv1 supplied to the analog-to-digital 
converting module 101. 
Assuming now that the multi-bit address signal represented by the column 3c 
is supplied from the bus controller 105 to all of the modules 101 to 104, 
the first address and the second address respectively activate the data 
source 121 and the destination 122 and switching elements 121b and 122b 
are closed. If the data source 121 stores pieces of sound information, a 
digital data signal indicative of the pieces of sound information is 
delivered from the data source 121, propagated by the data bus 109 and 
reaches the destination 122. Thus, various combinations of the data source 
121 and the destination 122 are established by the address signals ADD and 
the single data transmission is repeated for every combination in each 
time slot. This enhances the data transmission rate. As described 
hereinbefore, since the sampling time period is adjusted to the sampling 
cycle for the analog electric sound signal Sv1, a real time data 
transmission is achieved from the analog-to-digital converting module 101 
to a destination such as, for example, a digital-to-analog converting 
module 103 if one of the pieces of address information in every sampling 
time period designates the analog-to-digital converting module 101 as the 
data source 121. If, on the other hand, a high speed data transmission is 
requested, the same module is repeatedly designated by the pieces of 
address information during a single sampling time period. 
The modules 101 to 104 enter the broadcasting mode of operation in the 
presence of the lowermost block of value "0" as shown in FIG. 11. The 
modules 101 to 104 have 16-bit broadcasting data registers BR, 
respectively, and the main controlling unit 106 provides a 16-bit group 
address to the respective broadcasting data register BR. The sixteen bits 
of the broadcasting register BR correspond to sixteen destination groups, 
respectively, and each bit indicates whether or not the module belongs to 
the corresponding designation group. If the bit is "0", the module belongs 
to the corresponding designation group; however, the bit "1" indicates 
that the module does not belong to the corresponding designation group. 
For example, the broadcasting register BR of the destination 122 memorizes 
a bit string (01 . . . 10), and, therefore, the destination 122 belongs to 
the first and sixteenth designation groups only. 
When a broadcasting data is written into the register BR of each module, 
the main controlling unit 106 successively produces the multi-bit address 
signal ADD which is supplied to the bus controller 105. Each of the 
address signal ADD is temporally stored in the address queue 120 and 
sequentially supplied to all of the modules 101 to 104 through the address 
bus 110. When the main controlling unit 106 requests the modules 101 to 
104 to enter the broadcasting mode of operation, the lowermost block is 
set to value "0", and all of the modules 101 to 104 acknowledge the 
broadcasting mode of operation. In the broadcasting mode of operation, all 
of the modules 101 to 104 compare the first address indicative of the data 
source with the individual addresses, respectively, so as to see whether 
or not the bus controller 105 designates as the data source 121. However, 
the second address is compared with each of the broadcasting data stored 
in each register BR, and the switching element 122b is closed by an OR 
gate 122d upon matching the bit "0" of the second address with the 
corresponding bit of the group address. 
Assuming now that the second address has a bit string of (11 . . . 10) 
designating the sixteenth group, the modules constituting the designation 
have respective broadcasting data with the fifteenth bit of "0", and the 
designation 122 is activated to participate the broadcasting data 
transmission. The module designated as the data source 121 put the digital 
data signal indicative of pieces of sound information on the data bus 109, 
and the data bus 109 propagates the digital data signal. When the digital 
data signal reaches the modules constituting the destination 122, the 
digital data signal is memorized in the destination 122. Thus, the pieces 
of sound information represented by the digital data signal are 
concurrently sent the designated modules such as, for example, the 
digital-to-analog converting module 103 and the DSP module 104. 
If the broadcasting data transmission is established between the 
analog-to-digital converting module 101 (as the data source 121) and the 
digital-to-analog converting module; 103 as well as the DSP module 104, 
the analog electric sound signal Sv1 is retrieved in the digital-to-analog 
converting module 103 and transferred to the sound system 103b for 
reproduction of the sound. Since the digital data signal is further 
transmitted to the DSP module 104, the waveform of the sound is 
concurrently recorded. Thus, the reproduction and the recording are 
concurrently achieved in a single time slot under the broadcasting mode of 
operation. The data transmission system shown in FIG. 8 is further 
applicable to an audio recording/reproducing system shown in FIG. 12. The 
audio recording/reproducing system shown in FIG. 12 comprises an 
analog-to-digital converting module 131, a digital-to-analog converting 
module 132, a digital input/output module 133 associated with a digital 
sound system 134 outside of the audio recording/reproducing system, a DSP 
module 135, and a disc controlling module 136 for a hard disc 137, and 
these modules 131, 132, 133, 135 and 136 are communicable with one another 
through a data bus 138. The audio recording/reproducing system further 
comprises a bus controller 139 coupled to those modules 131, 132, 333, 135 
and 136 through a control bus 140 and an address bus 141, and the bus 
controller 139 is under the control of a main controlling unit 142. A user 
provides instructions from a manipulating panel 143 to the main 
controlling unit 142. The analog-to-digital converting unit 131, the 
digital-to-analog converting unit 132 and the DSP module 135 participate 
recording, converting and reproducing operations on a sound as similar to 
the sound synthesizing system shown in FIG. 9. 
The audio recording/reproducing system shown in FIG. 12 also enters the 
single data transmission mode and the broadcasting mode of operation and 
achieves a complex task in the broadcasting mode of operation. For 
example, a digital sound signal supplied from the digital sound system is 
transferred through the digital input/output module 133 to the data bus 
138 and the digital-to-analog converting module 132 retrieves an analog 
sound signal for reproducing sounds. Moreover, since the digital sound 
signal is further provided to the disc controlling module 75 in the 
broadcasting mode of operation, the digital sound signal is concurrently 
recorded in the hard disc 137 in the same time slot. 
Third Embodiment 
Turning to FIG. 13 of the drawings, another data transmission system 
embodying the present invention comprises a main controlling unit 151 for 
sequentially producing pieces of address information, a timing controlling 
unit 152 having a timing control section 152a supplied from the main 
controlling unit 151 with the pieces of address information and memorizing 
the pieces of address information in an address queue established therein, 
and a plurality of component units including component units 153 and 154 
sequentially supplied from the timing controlling section 152a with the 
piece of address information at every timing and transmitting a data 
signal therebetween. The timing control unit 152 further has a cycle 
controlling section 152b which controls the timing controlling section 
152a not to send the next piece of address information while the component 
unit 153 or 154 is operating. 
In operation, the main controlling unit 151 successively produces the 
pieces of address information and supplies the pieces of address 
information to the timing controlling unit 152. The pieces of address 
information enter an address queue formed in the timing controlling 
section 152a and sequentially read out at respective predetermined 
timings. Each of the pieces of address information is supplied to all of 
the component units, and each component unit compares the pieces of 
address information with an individual address assigned thereto. Each 
piece of address information is indicative of a first address of a data 
source and a second address of a destination, and at least two of the 
component units acknowledge themselves to be designated as the data source 
and the destination, respectively. If the component units 153 and 154 are 
respectively designated as the data source and the destination, the data 
bus 156 is occupied by the component units 153 and 154, and a data signal 
is transmitted from the component unit 153 to the component unit 154 
through the data bus 156 at a time slot defined by the timing controlling 
section 152a. If the next piece of data information designates other 
component units as the data source and the destination, a data 
transmission is carried out therebetween at the next time slot. Thus, the 
data transmission can be repeated between the data source and the 
destination in every time slot. If a large amount of data information is 
transmitted from one of the component units to another component unit, a 
series of the pieces of address information repeatedly designate these 
component units as the data source and the destination. If the data source 
or the destination takes too much time to operate, the cycle controlling 
section 152b prohibits the timing controlling section 152a from changing 
the designation of the data source and the destination, and, for this 
reason, the data transmission cycle can be prolonged over the sampling 
time period. 
The data transmission system shown in FIG. 13 is applicable to a sound 
synthesizing system illustrated in FIG. 14.. The sound synthesizing system 
shown in FIG. 14 comprises an analog-to-digital converting module 161 
associated with a microphone 161a for converting an analog electric sound 
signal Sv11 into a series of digital sound signal Sd1, a waveform memory 
module 162 for storing various waveforms of sounds in the digital form, a 
digital-to-analog converting module 163 operative to retrieve the analog 
sound signal and coupled to a sound system 163a, and a DSP module 164 
operative to modify a waveform, and these modules 161 to 164 selectively 
serving as the component units 153 to 154. A data bus 165 interconnects 
the modules 161 to 164, and a data transmission is carried out between the 
modules designated as a data source and a destination. The sound 
synthesizing system further comprises a bus controller 166, a main 
controlling unit 167 and a combined unit 168 of a keyboard and a 
manipulating panel, and the bus controller 166 are coupled to the modules 
161 to 164 through a control bus 169 and an address bus 170. Since the 
modules 161 to 164 are assigned individual addresses, respectively, the 
bus controller 166 designates two modules as a data source and a 
designation for data transmission. A user produces pieces of musical 
information indicative of tones assigned to depressed keys, an effect 
requested to be imparted to sounds and so forth, and the pieces of musical 
information are fed to the main controlling unit 167. Though not shown in 
the drawings, a central processing unit and memory units are incorporated 
in the main controlling unit and assigns tasks to the modules 161 to 164, 
respectively. The main controlling unit 167 further produces pieces of 
address information, and each piece of address information indicative of a 
first address of the data source and a second address of the destination. 
The pieces of address information are sequentially supplied to the bus 
controller 166 and form an address queue in the bus controller 166. The 
bus controller 166 distributes the pieces of address information through 
the address bus 170 to the modules 161 to 164 in synchronization with a 
timing signal TM, and a data transmission is carried out between the data 
source and the destination. Each timing signal TM defines a time slot for 
a single data transmission, and each of the modules 161 to 164 can report 
an operational status to the bus controller 166 through the control bus 
169. An individual address is assigned to the main controlling unit 167, 
and the main controlling unit 167 is capable of direct communication with 
the modules 161 to 164 through the data bus 165. Then, the main 
controlling unit 167 can achieve complex tasks on waveform modification 
through the direct communication with the modules 161 to 164. Various 
discrete control signal lines are further provided in the sound 
synthesizing system, however, they are omitted from FIG. 14 for the sake 
of simplicity. 
FIG. 15 shows a bus control using the control bus 169, and the control bus 
169 has an MSYNC section 169a. The bus controller 166 produces several 
synchronous timing signals, and the other section 169b propagates the 
synchronous timing signals to the modules 161 to 164 as will be described 
hereinlater in detail. 
The modules 161 to 164 respectively have driver circuits DR1, DR2, . . . 
each implemented by an open-collector circuit, and the driver circuits 
DR1, DR2, . . . supplies BUSY signals of an active low level to the MSYNC 
section 169a. A terminator 169c is coupled between one end of the MSYNC 
section 169a and a source of positive high voltage level Vdd so as to keep 
the MSYNC section 169a high in the absence of the BUSY signal of the 
active low voltage level. When one of the modules 161 to 164 is activated 
for a data transmission, the BUSY signal of the active low voltage level 
takes place and allows the MSYNC section 169a to go down to the low 
voltage level. This means that the operational status is reported to the 
bus controller 166 through the MSYNC section 169a. The terminator 169c, 
the MSYNC section 169a and the driver circuits DR1, DR2, . . . as a whole 
constitute a circuit to be said as "wired-AND gate". 
The modules 161 to 164 are similar in behavior to those of the first 
embodiment, and no description is incorporated hereinbelow for avoiding 
repetition. 
Turning to FIG. 16 of the drawings, the arrangement of the bus controller 
166 is illustrated in detail. The bus controller 166 comprises a first 
random access memory unit 166a and a second random access memory unit 
166b, and each of the random access memory units 166a and 166b has an 
address port (abbreviated as "ADD") supplied with an address signal Sam 
indicative of a memory address of the random access memory unit 166a or 
166b, a data port (designated by "DATA"), a chip select terminal and a 
write-in control terminal. The random access memory unit 166a or 166b is 
activated in the presence of a chip select signal of an active low level 
supplied to the chip select terminal. If a write-in control signal of an 
inactive high level is supplied to the write-in control terminal, data 
bits are read out from memory cells indicated by an address signal Sam fed 
to the address port of the activated memory unit 166a or 166b to the data 
port thereof; however, data bits supplied to the data port are written 
into memory cells indicated by the address signal Sam in the presence of 
the write-in control signal of the active low level. If the chip select 
signal remains in the inactive high level, the data port enters a 
high-impedance state, and, therefore, no communication is established 
between the memory cells and the outside thereof. 
The bus controller 166 further comprises first and second switching units 
166c and 166d each having a plurality of switching elements, and the first 
and second switching units 166c and 166d are responsive to a controlling 
signal Sr fed from a RAM controlling circuit 166e. Namely, if the first 
and second switching units 166c and 166d are changed to the state shown in 
FIG. 16, the first switching unit 166c allows the main controlling unit 
167 to rewrite data bits stored in the first random access memory unit 
166a. However, since the second random access memory unit 166b is supplied 
at the chip select terminal with the active low level and at the write-in 
control terminal with the inactive high voltage level, the second random 
access memory unit 166b becomes responsive to the address signal Sam fed 
from a counter circuit 166f and the address signal Sam is indicative of an 
address sequentially incremented by clock signal Sc1 fed from a timing 
generating circuit 166g. Then, the second random access memory unit 166b 
provides data bits to the output port thereof. The second switching unit 
166d relays the data bits thus read out to a tri-state buffer circuit 166h 
which in turn transfers the data bits to the address bus 170 as the 
address signal indicative of the first and second addresses. 
If, on the other hand, the first and second switching units 166c and 166d 
are changed from the states shown in FIG. 16 to the opposite states or all 
of the switching elements provide signal paths to the other contacts, the 
second random access memory unit 166b is communicable with the main 
controlling unit 167, and the first random access memory unit 166a 
supplies data bits to the address bus 170 in synchronization with the 
address signal Sam fed from the counter circuit 166f. 
As described hereinbefore, the timing generating circuit 166g supplies the 
clock signal Sc1 to the counter circuit 166f for incrementing the memory 
address indicated by the address signal Sam. The timing generating circuit 
166g is further operative to define a series of time slots. Namely, a 
system clock signal CL is supplied to the timing generating circuit 166g, 
and the timing generating circuit 166g produces a time slot controlling 
signal St (which is equivalent to the timing signal TM in FIG. 14) on the 
basis of the system clock signal CL. The time slot controlling signal. St 
is fed through a buffer circuit 166i to the control bus 169, and each time 
slot starts with the time slot controlling signal St. Each time slot is 
defined as "a unit of time interval for a single data transmission" in the 
sound synthesizing system shown in FIG. 14. Each module 161 to 164 is 
responsive to the time slot controlling signal St and two of the modules 
161 to 164 designated as the data source and the destination occupies the 
data bus 169 over the single time slot for the data transmission. The time 
slot controlling signal St is further supplied to the tri-state buffer 
circuit 166h for synchronous operation. Detailed description will be made 
hereinlater. 
Since the clock signal Sc1 is delivered at every time slot, the counter 
circuit 166f is incremented in synchronization with the time slot 
controlling signal St. The counter circuit 166f starts at value "0" and 
increases the value to "N". When the value reaches "N", the counter 
circuit 166f returns to value "0" and repeats the counting operation 
between values "0" and "N". The value from "0" to "N" is indicative of the 
memory address assigned to a group of the memory cells incorporated in 
either random access memory unit 166a or 166b, and, therefore, the address 
signal Sam circulates between the memory address "0" and the memory 
address "N". The memory addresses "0" to "N" designates (N+1) pairs of the 
data source and the destination and controls (N+1) data transmissions. 
Since the (N+1) data transmissions need (N+1) time slots, a sampling time 
period consists of (N+1) time slots. In this instance, the sampling time 
period is equivalent to a sampling interval of an analog electric sound 
signal supplied to the analog-to-digital converting module 161. 
When the counter circuit 166f reaches value "N", the next clock signal Sc1 
causes an overflow state to take place in the counter circuit 166f, and 
the overflow terminal OVF thereof is shifted to logic "1" level. In the 
overflow state, the counter circuit 166f interrupts the counting operation 
until a reset signal of logic "1" level is applied to the reset terminal R 
thereof. The overflow terminal OVF is coupled to an AND gate 166j, and 
another input terminal of the AND gate 166j is coupled to the MSYNC 
section 169a of the control bus 169. As described hereinbefore, the MSYNC 
section 169a remains in the high voltage level or logic "1" level as long 
as no module enters the operational status, and, for this reason, the AND 
gate 166j supplies logic "1" level to the reset terminal R if (N+1) data 
transmissions are completed upon occurrence of the overflow state. Then, 
the counter circuit 166f is released from the overflow state, and the 
counting value returns to "0". However, if an operation of a component 
unit is not completed in the (N+1)th time slot, the BUSY signal of the 
active low voltage level causes the MSYNC section 169a to be still in the 
low voltage level or logic "0" level, and, for this reason, the AND gate 
166j never resets the counter circuit 166f. Since the output signal Srt of 
the AND gate 166j is further supplied to the RAM controlling circuit 166e 
and causes the RAM controlling circuit 166e to change the states of the 
first and second switching units 166c and 166d, the timing for change is 
delayed until the operation of the component unit is completed. When the 
MSYNC section 169a is recovered to the high voltage level, the AND gate 
166j produces the output signal Srt, and allows the counter circuit 166f 
to restart. In the presence of the output signal Srt, the RAM controlling 
circuit 166e produces the control signal Sr and allows the first and 
second switching units 166c and 166d to change the signal paths. The 
output signal Srt is further supplied to the control bus 169 through a 
buffer circuit 166k. The time interval between the counting value "0" and 
the occurrence of the output signal. Srt is hereinbelow referred to as 
"cycle". If the MSYNC section 169a remains in the high voltage level or 
logic "1" level, the cycle is equivalent to the sampling time period. 
In this instance, the timing generating circuit 166g, the counter circuit 
166f and the RAM controlling circuit 166e as a whole constitute address 
information generating means, and the AND gate 166j serves as a logic 
gate. 
The circuit behavior of the bus controlling circuit is similar to that of 
the bus controlling circuit 48 as long as the MSYNC section 169a is in the 
high voltage level or logic "1" level. For this reason, the data 
transmission completed within a single sampling time period is briefly 
described with reference to FIG. 17 only, and description is focused upon 
the data transmission cycle over a single sampling time period. 
Assuming now that the pieces of address information enter an address queue 
Qa produced in either random access memory unit 166a or 166b of the bus 
controller 166, every block in the upper row Qa1 is paired with the 
corresponding block in the lower row Qa2, and each block pair indicates 
the piece of address information. Each piece of address information 
contains a first address of a data source 191 (represented by the block in 
the upper row Qa1) and a second address of a destination 192 (represented 
by the block in the lower row Qa2), and these addresses are represented by 
data bits or a data bit group memorized in either first or second random 
access memory unit 166a or 166b. In the following description, one of the 
analog-to-digital converting module 161, the waveform memory module 162 
and the DSP module 164 is designated as the data source, and one of the 
digital-to-analog converting module 163, the waveform memory module 162 
and the DSP module 164 serves as the destination. 
When the sequential read-out operation reaches the hatched blocks in the 
address queue Qa, the piece of address information or the data bit group 
is read out to the address bus 170 and the addresses are respectively 
transferred to the modules 161 and 164 in the time slot "4". The address 
of the data source is distributed to all of the modules 161 to 164, and 
the modules 161 to 164 compares the address of the data source with the 
individual addresses assigned thereto. Only the module serving as the data 
source 191 finds that the first address to be distributed is matched with 
the individual address assigned thereto through the comparison carried out 
by a component comparator 191a, and the component comparator 191a closes a 
component switching element 191b. Then, a data signal indicative of sound 
data to be requested is put on the data bus 165. 
The address of the destination 192 is also distributed to all of the 
modules 161 to 164 within the same time slot "4" and is compared with the 
individual addresses assigned the respective modules 161 to 164. In 
another module serving as the destination 192, a component comparator 192a 
allows a component switching element 192b to be close upon matching the 
second address of the destination 192 with the individual address. The 
data signal indicative of the sound data passes through an interface 192d, 
and the sound data is processed through the function of the module. Thus, 
the bus controller 166 sequentially designates two of the modules 161 to 
164 as the data source 191 and the destination 192 in every time slot and, 
accordingly, allows various data to be transmitted through the single data 
bus 165. If the MSYNC section 169a is recovered to the high voltage level 
at a termination of a sampling time period, the counter circuit is 
immediately reset to value "0" upon an occurrence of the overflow, and the 
data transmissions and the operation of the module are completed with a 
single sampling time period equivalent to a single cycle as shown in FIG. 
18A. 
If a plurality of time slots are assigned to two of the modules 161 to 164, 
a large amount of the sound data is transmitted from the data source 191 
to the destination 192. 
However, if a module consumes a time period longer than a single sampling 
period, the cycle is prolonged until a completion of the operation 
thereof. Namely, a complex data processing consumes a large amount of time 
period, the data transmission from the main controlling unit 167 to the 
DSP module 164 is carried out in an extension as shown in FIG. 18B. 
Assuming now that a series of the time slots selected from "0" to "N" of a 
single sampling time period are assigned to the data transmission from the 
main controlling unit 167 to the DSP module 164, the upper blocks 
repeatedly designate the main controlling unit 167, and each of the lower 
blocks stands for the second address indicative of the DSP module 164. 
When the memory address "0" is supplied to either random access memory 
unit 166a or 166b, the data bits indicative of the first and second 
addresses are read out from the random access memory unit 166a or 166b to 
the address bus 170 in synchronization with the time slot controlling 
signal St. The main controlling unit 167 acknowledges itself designated as 
the data source 191, and the DSP module 164 is ready for receipt of the 
data to be transmitted from the main controlling unit 167. A part of the 
data is transmitted from the main controlling module 167 to the DSP module 
164 in the first time slot "0", and the memory address is incremented to 
"1" for the second data transmission. Thus, the data are transmitted from 
the main controlling unit 167 to the DSP module 164 while the time slot 
proceeds from "0" to "N". The MSYNC section 169a of logic "0" level 
prohibits the AND gate 166j from producing the output signal Srt, and, for 
this reason, the counter circuit 166f remain in the overflow state. This 
results in that the address signal ADD retains the memory address "N" and 
that no alternation between the random access memory units 166a and 166b 
takes place. Then, the main controlling unit 167 continues to occupy the 
data bus 165 and the data transmission is continued over the sampling time 
period. 
If all of the data are transmitted from the main controlling unit 167 to 
the DSP module 164, the buffer circuit of the main controlling unit 167 
allows the MSYNC section 169a to recover to the high voltage level or 
logic "1" level. With logic "1" level on the MSYNC section 169a, the AND 
gate 166j produces the output signal Srt which is fed to the counter 
circuit 166f for reset as well as the RAM controlling circuit 166e for 
alternation between the random access memory units 166a and 166b. This 
results in that a new sampling time period starts with the first time slot 
"0". FIG. 19 illustrates an automatic extension of sampling time period. 
Thus, the bus controller 166 shown in FIG. 16 achieves the data 
transmission for a real time processing and the automatic extension of 
sampling time period. 
The data transmission system shown in FIG. 13 is further applicable to an 
audio recording/reproducing system shown in FIG. 20. The audio 
recording/reproducing system shown in FIG. 20 comprises an 
analog-to-digital converting module 201, a digital-to-analog converting 
module 202, a digital input/output module 203 associated with a digital 
sound system 204 outside of the audio recording/reproducing system, a DSP 
module 205, and a disc controlling module 206 for a hard disc 207, and 
these modules 201, 202, 203, 205 and 206 are communicable with one another 
through a data bus 208. The audio recording/reproducing system further 
comprises a bus controller 209 coupled to those modules 201, 202, 203, 205 
and 206 through a control bus 210 and an address bus 211, and the bus 
controller 209 is under the control of a main controlling unit 212. A user 
provides instructions from a manipulating panel 213 to the main 
controlling unit 212. The analog-to-digital converting unit 201, the 
digital-to-analog converting unit 202 and the DSP module 205 participate 
recording, converting and reproducing operations on a sound as similar to 
the sound synthesizing system shown in FIG. 14. 
In the audio recording/reproducing system shown in FIG. 20, the data 
transmission for a real time processing is desirable for the digital sound 
system 204. A series of digital sound signals are transmitted from the 
digital sound system 204 to the digital input/output module 203, converted 
by interface and transmitted through the data bus 208 to the 
digital-to-analog converting module 202, and the digital-to-analog 
converting unit 202 retrieves an original analog waveform for reproducing 
the original sounds. While, sound data memorized in the DSP module 205 are 
transferred to the main controlling unit 212 for waveform modification 
and, thereafter, transmitted to the DISC controlling module 206 for disc 
recording. In this case, the main controlling unit 212 takes long time in 
the operation, and the operation does not finish within a single sampling 
period. Then, the bus controller extends the cycle and allows the 
processed data to reach the disc controlling module 206 within a single 
cycle. 
As will be understood from the foregoing description, the data transmission 
system according to the present invention effectively controls the data 
bus and enhances the data transmission rate without any sacrifice of 
simple data bus arrangement. 
Although particular embodiments of the present invention have been shown 
and described, it will be obvious to those skilled in the art that various 
changes and modifications may be made without departing from the spirit 
and scope of the present invention. For example, the sound synthesizing 
system shown in FIG. 11 is characterized by the broadcasting data having 
the bits respectively corresponding to address groups; however, the binary 
values represented by the broadcasting data may correspond to address 
groups, respectively. In this implementation, the address groups are 
increased to an arbitrary number less than 2.sup.16. 
The second address may be shared between the single data transmission mode 
of operation and the broadcasting mode of operation. If individual M 
modules are assigned addresses "0" to "M", respectively, the second 
address from "M+1" to "65535" can designate address groups without any 
lowermost block. In the second embodiment, the destination is constituted 
by the two component units in the broadcasting mode of operation. However, 
the destination may be constituted by more than two component units.