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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic exchange system, wherein it
is easy to alter the functions assigned to the keys of a terminal, and
also to a method of controlling such an electronic exchange system.
2. Description of the Related Art
Various types of electronic exchanges are used in telephone networks. Among
them is a private branch exchange (hereinafter referred to as "PBX"). The
PBX comprises a microcomputer. It can perform many functions at high
efficiency, owing to the application of software to the microcomputer.
Hence, the PBX not only can perform switching of telephone lines, but also
can provide other various services.
The terminals connected to the PBX, such as extension telephones and
attendants, also each have a microcomputer can perform various functions,
and are highly intelligent. For example, an attendant comprises a
microcomputer. It further comprises a handset, a response switch,
extension switches, indicator lamps (e.g., LEDs), and a buzzer. The
extension switches are to be coupled to extension telephone lines. The
indicator lamps are provided for the switches (i.e., the response switch
and the extension switches), respectively.
In use, the attendant is connected to the PBX. When the PBX receives a call
through an external telephone line (hereinafter referred to as "office
line"), it supplies a ringing signal to the attendant. In response to the
ringing signal, the buzzer incorporated in the attendant generates an
alarm. Hearing this alarm, the human operator at the attendant takes the
handset and pushes the response switch. When the response switch is thus
pushed, the attendant generates a signal. In response to this signal, the
PBX connects the office line to the attendant. As a result, the operator
and the caller on the other side of the office line can talk with each
other. The operator asks whom the caller wants to talk to.
Upon hearing whom the caller wishes to talked to, the operator checks
whether the indicator lamp is on or off which is assigned to the extension
telephone of the person being called.
If the indicator lamp is off, indicating that the extension telephone is
not occupied, the operator pushes the extension switch. Then, the PBX sets
the office line into a "suspended state," and supplies a ringing signal to
the extension telephone through the attendant and the extension telephone
line so that the extension telephone rings. Then, the receiver of the
extension telephone is taken off the cradle. The operator asks the user of
the extension telephone whether or not the user desires to receive the
call. If the user says he or she will receive the call, the operator
performs a transfer operation. The PBX connects the extension telephone to
the attendant, enabling the operator to speak with the caller. The
operator tells the called person that the caller wants to talk to him or
her. When the operator hears that the called party wants to speak to the
caller, then he or she operates the attendant, thereby releasing the
office line from the suspended state and connecting it to the extension
telephone line. As a result, the caller and the called party can talk with
each other.
As has been described, the attendant has a number of key switches assigned
to respective specific functions. These functions are performed by
operating the key switches, under the control of the software applied to
the microcomputer incorporated in the PBX. In other words, the functions
to which the key switches are assigned are controlled by the PBX. When the
operator pushes one of the key switches, for example, the extension key
which is assigned to the connection of the office line to the extension
telephone line A, the attendant generates a signal representing the code
allotted to this key switch. The code signal is transmitted to the PBX.
It should be noted that the PBX further comprises an I/O port and a memory.
The I/O port is connected to the attendant. The memory stores key-assign
data which is a key-data table showing the codes of the key switches, the
functions to which the key switches are assigned, and the logical numbers
of the buzzer and indicator lamps of the attendant.
Hence, when the code signal representing the code, which is allotted to the
extension switch the operator has pushed, is transmitted to the
microcomputer of the PBX through the I/O port, the PBX supplies the
attendant with the data item representing the logical number of the
indicator lamp provided for the pushed extension switch. In the attendant,
the indicator lamp identified by this data item is turned on.
The memory incorporated in the PBX has memory areas, which includes a
key-assign data area, an exchange-control program area, a fixed data area,
and a work area. The key-assign data, described above, is stored in the
key-assign data area.
As is evident from the above, both the attendant and the PBX are controlled
in accordance with the software. Therefore, the key switches of the
attendant can be assigned to various functions in any arbitrary way, and
these functions are performed by operating the key switches under the
control of the PBX.
Generally, in an electronic exchange system comprising an electronic
exchange and an intelligent terminals (e.g., an attendant), when any one
of the key switches of the terminal is pushed, the terminal generates a
signal representing the code of the pushed key switch and supplies this
code signal to the telephone exchange. In response to the code signal, the
telephone exchange performs the function to which the pushed switch is
assigned, or telephone exchanging, in accordance with the code signal. To
enable the telephone exchange to perform not only the telephone exchanging
but also the function to which any pushed switch is assigned, both the
terminal and the electronic exchange identify any switch key of the
terminal that has been pushed.
With the conventional electronic exchange system, it is indeed possible to
assign the key switches of the terminal to various function arbitrarily.
However, once the key switches have been assigned to specific functions,
respectively, by the manufacturer of the system, it is no longer possible
for the user to alter the key assignment unless the user changes the
programs stored in the memories of both the terminal and the electronic
exchange. Usually it is very difficult for the user to change these
programs. The flexibility of software control is not completely utilized
in the conventional electronic exchange systems.
SUMMARY OF THE INVENTION
Accordingly, it is the object of the present invention to provide an
electronic exchange system with which it is easy to alter the functions
assigned to the key switches of a terminal in accordance with an
operator's needs, and which is therefore operator-friendly.
According to a first aspect of the present invention, there is provided an
electronic exchange system which comprises a telephone exchange for
connecting extension lines to one another and also connecting an office
line to any extension line, and a terminal adapted to be connected to the
exchange, having a plurality of keys and designed to function as a
communication device as well.
The terminal comprises a first memory device for storing key-assign data
consisting of the codes of the keys, a data-receiving device for receiving
the key-assign data, a memory control device for instructing the first
memory device to store the key-assign data which the data-receiving device
has received from the telephone exchange, and a first control device for
reading a key code from the first memory device and supplying the key code
to the telephone exchange when the key identified by the key code is
operated. The memory control device is enabled to receive the key-assign
data when the terminal is initialized.
The telephone exchange comprises a second memory device for storing the
key-assign data and the data items representing the functions to which the
keys are assigned, a second control device for reading the key-assign data
from the second memory and supplying it to the terminal, upon determining
that the terminal is connected to the telephone exchange, and a third
control device for performing the functions specified by the key codes
transmitted from the terminal and also by the data items stored in the
second memory.
As has been pointed out, when the terminal is initialized, the first memory
device is rendered ready to store the key-assign data. At the same time,
the second control device supplies the key-assign data to the terminal.
These key-assign data are stored into the first memory device under the
control of the memory control device. Thereafter, when an operator at the
terminal pushes any one of the keys, the first control device reads the
code of this key from the first memory device and supplies the key code to
the telephone exchange. The exchange identifies that data item stored in
the second memory device which corresponds to the key code, and then
performs the function represented by the data item.
Since the key-assign data stored in the second memory means is
automatically stored into the first memory device when the terminal is
initialized, the operator need not operate the terminal to store the
key-assign data into the first memory device. In view of this, the system
according to the invention is operator-friendly.
Also, the operator need not operate the keys of the terminal to alter the
key assignment. It is sufficient for him or her to operate the keys of the
telephone exchange to alter the key assignment. In this respect, too, the
system of the invention is operator-friendly.
According to a second aspect of the present invention, there is provided an
electronic exchange system which comprises a telephone exchange for
connecting extension lines to one another and also for connecting an
office line to any extension line, with a terminal adapted to be connected
to the exchange, having a plurality of keys and designed to function as a
communication device, too. And an additional unit adapted to be connected
to the terminal, having a plurality of keys and designed to generate the
code of any of these keys that are operated.
The additional unit comprises an input/output device, a first memory means
for storing data, and a first control device for supplying a start signal
via the input/output device when the unit is initialized, for storing
key-assign data supplied through the input/output device, into the first
memory device, for reading the code of any one of the keys when the key is
operated, and for outputting the key code.
The terminal comprises an interface device connected to the additional
unit, for receiving signals from, and supplying signals to, the additional
unit, a second memory device for storing the key-assign data consisting of
the codes of the keys of the terminal and those of the additional unit, a
data-receiving device for receiving the key-assign data when the terminal
is initialized, and a memory control device for instructing the second
memory device to store the key-assign data into the second memory device,
for determining whether or not the additional unit is connected to the
terminal, for reading the key-assign data for the additional unit from the
second memory upon determining that the additional unit is connected to
the terminal, and for supplying the key-assign data to the additional unit
through the interface device. A second control device reads a key code
from the first memory device and supplies the key code to the telephone
exchange when the key identified by the key code is operated, and supplies
a key code to the telephone exchange when the key code is transmitted to
the interface means from the additional unit.
The telephone exchange comprises a third memory device for storing the
key-assign data and the data items representing the functions to which the
keys are assigned, a third control device for reading the key-assign data
from the second memory and supplying it to the terminal, upon determining
that the terminal is connected to the telephone exchange, and a fourth
control device for performing the functions specified by the key codes
transmitted from the terminal and also by the data items stored in the
third memory.
As has been pointed out, when the additional unit is connected to the
terminal, and the terminal is connected to the telephone exchange, the
terminal is automatically initialized. At the same time, the second memory
device is rendered ready to store the key-assign data. In the telephone
exchange, the third control device reads the key-assign data from the
second memory device and supplies it to the terminal, upon determining
that the terminal is connected to the exchange. In the terminal, the
second memory device stores the key-assign data. Of these data, the codes
of the keys of the additional unit are transmitted to the additional unit.
In the additional unit, these key codes are stored into the first memory
device.
Thereafter, when an operator at the additional unit pushes any one of the
keys, the first control device reads the code of this key from the first
memory device and supplies the key code to the terminal. This key code is
transmitted from the terminal to the telephone exchange. Similarly, when
an operator at the terminal pushes any one of the keys, the second control
device reads the code of this key from the second memory device and
supplies the key code to the telephone exchange. The exchange identifies
the data item stored in the third memory device and corresponding to the
key code transmitted from either the additional unit or the terminal, and
then performs the function represented by the data item.
As has been described, when the terminal is connected to the exchange and
initialized, not only the key-assign data for the terminal, but also the
key-assign data for the additional unit, are read from the third memory
device and transmitted from the exchange to the terminal. Both types of
data are stored into the second memory device. When the additional unit is
connected to the terminal and initialized, the key-assign data for the
additional unit is read from the second memory device and transmitted from
the terminal to the additional device. This key-assign data is stored into
the first memory device. Hence, in case the keys provided on the terminal
are insufficient for connecting the office line to the extension lines,
the additional unit is connected to the terminal, whereby the keys
provided on the additional unit make up for any insufficiency.
Further, as has also been pointed out, when the terminal is connected to
the telephone exchange, the keys of the terminal are automatically
assigned to various functions in accordance with the data stored in the
exchange. Similarly, when the additional unit is connected to the
terminal, the keys of the additional unit are automatically assigned to
various functions in accordance with the data stored in the exchange.
Therefore, the operator need not operate the terminal to store the
key-assign data into the second memory device. Nor does he or she need to
operate the additional unit to store the key-assign data into the first
memory device. In view of this, the system according to the invention is
operator-friendly.
Moreover, the data items stored in the third memory device and representing
the functions assigned to these keys can be altered by operating the
keyboard of the telephone exchange. The key codes associated with the data
items thus altered are automatically read from the third memory device and
stored into the second memory device when the terminal is connected to the
exchange, and those of the key codes which represent the keys of the
additional unit are are automatically read from the second memory device
and stored into the first memory device when the additional unit is
connected to the terminal. Hence, the operator needs to operate neither
the terminal nor the additional unit to alter the functions to which the
keys of the terminal or the additional unit are assigned. In this respect,
too, the system of the invention is operator-friendly.
According to a third aspect of the present invention, there is provided a
method of controlling an electronic exchange system which comprises a
telephone exchange for connecting extension lines to one another and also
for connecting an office line to any extension line, and a terminal
adapted to be connected to the exchange and having a plurality of keys.
The method comprises the steps of: storing key-assign data consisting of
the codes of the keys and also the data items representing the functions
to which the keys are assigned, into the telephone exchange; determining
whether or not the terminal is connected to the telephone exchange, and
supplying the data-assign data to the terminal when it is determined that
the terminal is connected to the telephone exchange; enabling the terminal
to receive the key-assign data when the terminal is initialized, and
storing the key-assign data into the terminal when the terminal receives
the key-assign data; supplying a key code from the terminal to the
telephone exchange when the key identified by the key code is operated;
and causing the telephone exchange to perform the functions specified by
the key codes transmitted from the terminal and also by the data items
stored in the telephone exchange.
In this method, when the terminal is connected to the telephone exchange,
the key-assign data is automatically transmitted from the exchange to the
terminal and stored into the terminal. When an operator at the terminal
pushes any one of the keys, the code of this key is transmitted from the
terminal to the exchange. The exchange identifies the data item
corresponding to the kay code, and then performs the function represented
by the data item.
Since the key-assign data is automatically supplied from the exchange to
the terminal when the terminal is initialized, the operator need not
operate the terminal to store the key-assign data into the terminal. Also,
the operator need not operate the keys of the terminal to alter the key
assignment. It is sufficient for him or her to operate the telephone
exchange to alter the key assignment. In this respect, too, the system of
the invention is operator-friendly.
According to a fourth aspect of the present invention, there is provided a
method of controlling an electronic exchange system which comprises a
telephone exchange for connecting extension lines to one another and also
for connecting an office line to any extension line, and a terminal
adapted to be connected to the exchange, having a plurality of keys and
designed to function as a telephone, too, and an additional unit adapted
to be connected to the terminal and having a plurality of keys.
This method comprises the steps of: storing key-assign data consisting of
the codes of the keys of the terminal and those of the additional unit and
also the data items representing the functions to which the keys are
assigned, into the telephone exchange; determining whether or not the
terminal is connected to the telephone exchange, and supplying the
data-assign data to the terminal when it is determined that the terminal
is connected to the telephone exchange; enabling the terminal to receive
key-assign data from the telephone exchange when the terminal is
initialized, and storing the key assign data into the terminal when the
key-assign data is transmitted to the terminal from the telephone
exchange; determining whether or not the additional unit is connected to
the terminal, and supplying the key-assign data for the additional unit
from the terminal to the additional unit when it is determined that the
additional unit is connected to the terminal; storing into the additional
unit the kay-assign data transmitted from the terminal when the terminal
receives the key-assign data; supplying a key code from the additional
unit to the terminal when the key identified by the key code is operated;
supplying a key code from the terminal to the telephone exchange when that
key of the terminal which is identified by the key code is operated, and
also supplying to the telephone exchange a key code, if any, which has
been transmitted from the additional unit to the terminal; and causing the
telephone exchange to perform the functions specified by the key codes
transmitted from the terminal and also by the data items stored in the
telephone exchange.
In this method, when the terminal is connected to the telephone exchange,
the key-assign data is automatically transmitted from the exchange to the
terminal and stored into the terminal. When an operator at the terminal
pushes any one of the keys, the code of this key is transmitted from the
terminal to the exchange. The exchange identifies the data item
corresponding to the key code, and then performs the function represented
by the data item. Also, when the additional unit is connected to the
terminal, the codes of the keys of the additional unit, i.e., part of the
key-assign data, are automatically transmitted from the terminal to the
additional unit and stored into the additional unit. When an operator at
the terminal pushes any one of the keys, the code of this key is
transmitted from the additional unit to the to the exchange through the
terminal. The exchange identifies the data item corresponding to this key
code, and then performs the function represented by the data item.
Since the key-assign data is automatically transmitted from the exchange to
the terminal when the terminal is initialized, and that part of the
key-assign data which are the codes of the keys of the additional unit is
automatically transmitted from the terminal to the additional unit, the
operator need not operate the terminal or the additional unit to store the
key codes into the terminal and the additional unit. Nor is it necessary
for the operator to operate the keys of the terminal or the additional
unit to alter the key assignment. It is sufficient for him or her to
operate the telephone exchange to alter the key assignment. In this
respect, too, the system of the invention is operator-friendly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an electronic exchange system according
to a first embodiment of the present invention;
FIG. 2 is a plan view, illustrating the outer appearance of the attendant
incorporated in the system shown in FIG. 1;
FIGS. 3 and 4 are diagrams representing the memory maps of the system shown
in FIGS. 1 and 2;
FIG. 5 is a diagram explaining how various operations are sequentially
performed in the system shown in FIGS. 1 and 2;
FIG. 6 is a flow chart explaining how the system of FIGS. 1 and 2 operates;
FIG. 7 is a block diagram showing an electronic exchange system according
to a second embodiment of the present invention;
FIG. 8 is a plan view illustrating the outer appearance of the attendant
incorporated in the system shown in FIG. 7;
FIGS. 9A and 9B form a flow chart explaining how the system shown in FIGS.
7 and 8 operates;
FIG. 10 is a block diagram showing the terminal CPU 9 used in the system
illustrated in FIG. 1;
FIG. 11 is a block diagram illustrating the CPU 3 shown in FIG. 1;
FIG. 12 is a block diagram showing the structure of the terminal CPU 9 used
in the system illustrated in FIG. 7;
FIG. 13 is a block diagram showing the structure of the controller 84
incorporated in the additional unit (i.e., a keyboard) used in the system
illustrated in FIG. 7;
FIG. 14 a block diagram showing the structure of the CPU 3 incorporated in
the exchange exchange 1a of the system illustrated in FIG. 7; and
FIGS. 15A and 15B form a flow chart explaining how the system shown in
FIGS. 7 and 8 operates in a different way.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will now be described in detail, with
reference to the accompanying drawings. As will be understood from the
following description, the embodiments are electronic exchange systems
comprising an attendant each, used as a terminal. Nevertheless, the
present invention can be applied to an electronic exchange system having
telephones which are used as terminals.
The electronic exchange system according to a first embodiment will first
be described, with reference to FIG. 1, which is a block diagram. As is
shown in FIG. 1, the electronic exchange system comprises an electronic
exchange 1a and an attendant. The attendant comprises a controller 5a and
some other components (later described).
The electronic exchange 1a is designed to connect office lines to extension
telephone lines, and also to couple the extension telephone lines to one
another. The exchange 1a comprises a line controller (not shown), a CPU
(processor) 3, a control-signal way interface 4, a memory unit 20, a
transformer 31, a connector 32, and a power supply 33.
The line controller is designed to transmit signals to, and receive signals
from, any extension telephone line connected to an office line, and also
to supply power to a connected extension telephone line.
The CPU 3 controls various telephone-exchange operations. The memory 20
comprises at least a ROM and a RAM. The ROM stores an initial program
loader (IPL) program and the like. The CPU 3 executes the IPL program, so
that the control programs for controlling telephone exchanging and
specific functions are stored into the RAM. In other words, the RAM stores
various programs which the CPU 3 is to execute and the data which the CPU
3 needs to execute these programs. The RAM has a program work area. The
ROM of the memory unit 20 also stores a program which the CPU 3 executes
to supply key-assign data (i.e., key code data) to the controller 5a. The
key-assign data has been generated by operating a call-mode response key
15a of the attendant to initialize the controller 5a, and is stored into
the RAM of the memory unit 20 through an input port (not shown) of the
electronic exchange 1a. The CPU 3 executes the programs thus stored in the
RAM, thereby performing the telephone exchanging, assigning the key
switches of the attendant to special functions, and supplying data to the
controller 5a.
The control-signal way interface 4 is connected by the transformer 31 to
the connector 32. The interface 4 receives control signals to be
transmitted to the exchange 1a, and supplies control signals to the
controller 5a. The connector 32 is connected to a line L.
The power supply 33 supplies power to the other components of the
electronic exchange 1a. It supplies power to the controller 5a, too. More
specifically, a DC current of about 20 V is applied from the power supply
33 via the connector 32 to the line L. The transformer 31 electrically
insulates the power supply 33 from the signal system of the exchange 1a.
As is shown in FIG. 1, the attendant includes a plurality of LEDs 14, a
response switch (not shown), a call-mode response key 15a, a plurality of
extension key switches 15b, a dial-key pad 16, an handset 17, a speaker
18, and a liquid-crystal display (LCD) 46. The LEDs 14 are provided for
the extension key switches 15b, respectively. The liquid-crystal display
46 is used as a character display.
The controller 5a comprises a control-signal interface circuit 6, a CPU 9,
an LED controller 10, a key switch controller 11, a speech controller 12,
a handset controller 13, an LCD controller 41, a power unit 42, a
transformer 43, a modular connector 44, and a memory unit 70.
The control-signal interface circuit 6 is connected to the line L by the
transformer 43 and the modular connector 44; it is thus connected to the
electronic exchange 1a. The interface circuit 6 is designed to receive
control signals from the exchange 1a, and to supply control signals to the
exchange 1a.
The CPU 9 (hereinafter called "terminal CPU") is the main component of the
controller 5a, for controlling the attendant. The terminal CPU 9 controls
the attendant in accordance with the data stored in the memory unit 70.
The memory unit 70 comprises at least a ROM and a RAM. The ROM stores an
initial program loader (IPL) program. When the attendant is initialized,
the terminal CPU 9 automatically executes the IPL program, thus receiving
the key-assign data from the electronic exchange 1a and writing this data
into the ROM of the memory unit 70.
The LED controller 10 is designed to drive the LEDs 14 of the attendant,
which are provided for the response switch (not shown in FIG. 1 or 2), the
call-mode response key 15a, and the extension key switches 15b,
respectively. The key switch controller 11 is designed to detect which key
or key switch, i.e., the response key switch (not shown), the call-mode
response key 15a, or one of the extension key switches 15b, has been
pushed. The speech controller 12 is used to supply a ringing signal or a
speech signal to the speaker 18 of the attendant and also to the handset
controller 13, and to supply the electronic exchange (not shown) with the
speech signals generated by the handset 17.
The LCD controller 41 is designed to drive the liquid-crystal display 46
(i.e., the character display) in accordance with the display data and the
control signal, both transmitted from the terminal CPU 9.
The modular connector 44 connects the line L and the attendant. It is
coupled by the transformer 43 to the control-signal interface circuit 6.
The transformer 43 separates the signal component and the DC voltage
component (about 20 V) from each other, which are supplied together
through the line L.
The power unit 42 converts the DC voltage applied through the line L, into
a predetermined voltage which is required to drive the other components of
the attendant. It should be noted that the power unit 42 can be dispensed
with.
A power switch 45 is connected to the power unit 42. When the power switch
45 is closed, the attendant including the controller 5a is turned on. When
the switch 45 is opened, the attendant is turned off.
FIG. 2 is a plan view of the attendant. The LEDs 14, the call-mode response
key 15a, the extension key switches 15b, the dial-key pad 16, the handset
17, the speaker 18, and the liquid-crystal display 46, are arranged on an
operation panel.
FIG. 3 is a diagram showing the memory map of the memory unit 20
incorporated in the electronic exchange 1a. As can be clearly understood
from this figure, the memory unit 20 comprises an exchange-control program
area 20a, a fixed data area 20b, and a work area 20d. A key-assign data
area 20c is included in the work area 20d, and not in the fixed data area
20b, as in the corresponding memory unit incorporated in the conventional
electronic exchange system. Hence, the key-assign data stored in the data
area 20c can be altered whenever necessary.
FIG. 4 is a diagram illustrating the memory map of the memory unit 70 used
in the controller 5a. As is evident from this figure, the unit 70
comprises a terminal-control program area 70a and a work area 70c. A
key-assign data area 70b is included in the work area 70c. Thus, the
key-assign data stored in the data area 70b can also be altered whenever
required.
The key-assign data stored in the data area 70b consists of the codes of
the extension key switches 15b. When any one of the key switches 15b is
pushed, the key switch controller 11 detects this and supplies a detection
signal to the terminal CPU 9. In response to this signal, the terminal CPU
9 reads the code of the pushed key switch and supplies the key code to the
electronic exchange 1a via the control-signal interface circuit 6, the
transformer 43, and the modular connector 44.
FIG. 10 is a block diagram schematically showing the structure of the
terminal CPU 9 incorporated in the controller 5a. FIG. 11 is a block
diagram, too, schematically illustrating the structure of the CPU 3
incorporated in the electronic exchange 1a.
As is illustrated in FIG. 10, the terminal CPU 9 comprises a first control
unit 9a and a second control unit 9b. The first control unit 9a is
designed to initialize the attendant, to start waiting for any key code
upon initializing the attendant, and to store a key code into the
key-assigned data area 70b of the memory unit 70, upon receiving this code
from the attendant. The second control unit 9b reads any key code from the
data area 70b and supplies this key code to the electronic exchange (not
shown), upon receipt of the detection signal which is transmitted from the
key switch controller 11 and which shows that any one of the extension key
switches 15b of the attendant has just been pushed.
As is shown in FIG. 11, the CPU 3 of the electronic exchange 1a comprises a
function-registering control unit 3a, a key-code transfer unit 3b, and a
function-performing unit 3c. The function-registering unit 3a is designed
to register the key code identifying each key switch 15b and the data item
representing the function to which the key switch is assigned, in the
key-assign data area 20c of the memory unit 20. The key-code transfer unit
3b is designed to determine whether or not the attendant is connected to
the exchange 1a, to read the key | | |
