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BACKGROUND OF THE INVENTION
The present invention relates to a terminal controller and particularly to
a terminal controller in which a control system is incorporated to enable
to use a video data terminal from a plurarity of programs by spliting the
video screen of the video data terminal.
In recent years, it has been a common practice to utilize a network
configuration in which a plurality of computer systems are linked with
each other. For example, there is known a laboratory automation (LA)
control system comprising hierachically linked host machines (large-scale
computers) and local machines (small-scale computers).
The system network configuration aims at:
(1) effective communication resource utilization,
(2) distribution of communication system functions,
(3) flexible expansion of communication network, and
(4) labor saving in application systems.
The virtual telecommunication access method (VTAM) has been known as a
method for accessing other machines through communication lines and
provides the following advantages: (1) a plurality of terminals can share
a communication line, (2) application programs in any host machine can be
used at any location in the communication network, and (3) the application
programs need not perceive the network configuration. For system network
configurations and VTAM, refer to the IBM System Journal, Vol. 15, No. 1,
1976; an article entitled "Synchronous data link control: A perspective",
IBM Systems Journal, Vol. 13, No. 2, 1974 and "VOS3 ECS/VTAM Guide"
(manual of Hitachi Ltd.) 8080-3-140, 1980.
FIG. 1 illustrates an example of the system network configuration. The host
machines 1 and 2 are linked with each other via a communication line
through the communication control computers 3 and 4. The communication
control computers 3 and 4 can be connected in parallel to a plurality of
other machines in the network. A local machine (subhost machine) 5 is
linked with the communication control computer 3 of the host machine 1 or
with other local machines through a controller 6 which enables data
communication between these devices. The controller 6 is provided to
control communication procedures such as the high-level data link control
(HDLC) procedure and the synchronous data link control (SDLC) procedure.
In the system network configuration, application programs in the host
machine 1 can be used from a terminal 7 of the host machine 1 and also
from a terminal 8 of the host machine 2. Assuming that a time sharing
system (TSS) is used as the application program, a user program (TSS-AP) 9
runs under control of a TSS control program 10 and the TSS control program
10 utilizes a VTAM program 11 in the host machine 1.
To output a message from the user program 9 to the terminal 7 or 8, the
HDLC procedures are processed by a network control program 13 in the
communication control computer 3 through processing of the VTAM 11 and a
host operating system 12; and the message is output to the terminal 7 or
it is delivered to the communication control computer 4 to be transmitted
to the terminal 8. On the contrary, the above-mentioned processing need
only be reversed to input a message from the terminal 7 or 8.
Furthermore, application programs of the host machines 1 and 2 can be
accessed from a terminal connected to the local machine 5. The local
machine 5 is called a local machine or terminal controller having a
cluster control function.
In the local machine 5, a Hitachi network architecture subhost
communication program (HICOP) 18 runs under control of an operating system
17, further a data stream compatibility (DSC) program 19 operates under
the HICOP 18. The HICOP 18 is provided to carry out VTAM functions,
whereas the DSC program 19 is used to enable a terminal 16 connected to
the local machine 5 to be treated in the same way as for the terminal 7
connected to the host machine 1 when an input/output message is output to
the terminal 16 from the application program 9 in the host machine 1. This
means that the functions of terminal controllers are carried out by the
local machine 5 and the control programs 17-19. For the data streams
between the host machine 1 and the local machine 5 and processing
procedures of the HICOP 18 and the DSC program 19, refer to the co-pending
U.S. patent application Ser. No. 515,193 filed on July 19, 1983, which
corresponds to the Japanese Patent Application No. Sho 57-126341.
As explained above, the system network depicted in FIG. 1 provides the
following advantages by use of the VTAM and the cluster control function
of the local machine 5: (1) terminals connected to local machines can be
utilized as host machine terminals and (2) host machine capability and
resources can be used from local machine terminals.
Reference numeral 20 in FIG. 1 indicates a laboratory of a laboratory
automation (LA) system including hierarchically connected host machine 1
and local machine 5. The local terminal 16 and a measuring instrument
standard interface bus 21 are equipped in the laboratory 20. An
application program 23 (to be denoted as LAAP 1) and the like are used to
control measuring instruments and apparatuses 22 and to gather measured
data in the local machine 5, then the collected data is stored in a local
file 24.
In general, the host machine 1 is utilized to perform more precise analyses
on the collected data. The U.S. patent application Ser. No. 515,193 has
disclosed a control system which allows to use the terminal 16 connected
to a local machine as a control terminal for the application program 9 of
the host machine 1 and enables the host machine 1 to directly access the
local file 24, including effects of the control system.
When only the video terminal 16 is connected to the local machine 5, the
operator uses the terminal 16 as a control terminal for the application
program 23 to gather measured data, then the terminal 16 is used as a
control terminal for the application program 9 of the host machine 1 (,
which is called an expansion to a host TSS). That is, the terminal 16 is
logically separated from the application program 23 after the local
program 23 of the local machine 5 is finished and the terminal operates as
a terminal of the host TSS. This means that the terminal 16 is logically
connected to the HICOP 18 and DSC 19. Consequently, collection of the
measured data by use of the application program and analysis by means of
the application program 9 in the host machine 1 cannot be concurrently
carried out from a terminal.
Although the measurement and analysis can be naturally conducted by using a
terminal for controlling collection of measured data and a terminal for
analyzing data by a host machine, the number of expensive terminals is
increased and the space for the LA system in the laboratory is reduced.
Moreover, the operation becomes complex because only one operator must
handle two terminals.
Furthermore, if it is necessary to execute a plurality of application
programs from a video terminal, that is, if the outputs from several
application programs are to be split and displayed on the screen of a
video terminal, all programs that run simultaneously must be regenerated
so that the video terminal can be commonly used among them for the
following reasons:
(1) The common use of a video terminal must be perceived when each
application program manages the buffer for storing the output data stream,
and
(2) Each application program must be provided with a processing for
determining the destination application program to which a data item input
from the video terminal is to be input.
These modifications for existing application programs will necessitate a
tremendous time and cost.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a terminal controller
which enables to simultaneously execute at least two programs from a
terminal without causing any modifications on the existing application
programs.
Another object of the present invention is to provide a terminal controller
which enables arbitrarily change between the screen split operation mode
for allowing a split screen display of a plurality of application programs
on a screen of a video terminal and the ordinary screen operation mode for
allowing a single screen display of an application program on a screen of
a video terminal by inputting a special control code from the video
terminal to the terminal controller.
A terminal controller according to the present invention in a configuration
comprising video data terminals and a controller (including a minicomputer
or microcomputer) for controlling the video data terminal operates as
follows. When a video screen split command is issued from the terminal, a
special program in the terminal controller is initiated to set the
operation modes of the pertinent processing programs to allow at least two
programs can share the screen of the video data terminal. After the screen
split operation mode is set, the processing to merge screen display data
and the processing to distribute input data to an application program that
shares the relevant terminal are performed so that each application
program that runs independently can perform input/output processing for a
video terminal as if the terminal is dedicated only to the application
program.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and advantages of the present invention will
become apparent in the following description and the accompanying drawings
in which:
FIG. 1 is a diagram illustrating an example of the system network
configuration;
FIG. 2 is a diagram showing the video data terminal configuration and the
program configuration of a local machine when the screen of the video data
terminal is commonly used;
FIG. 3 depicts a diagram showing relationships between control programs in
the memory of the local machine according to the present invention;
FIG. 4 illustrates a schematic diagram showing in detail control tables
shown in FIG. 3;
FIG. 5 is a diagram showing a diagram showing the format of an input data
stream from a video data terminal;
FIG. 6 depicts a table listing examples of INC (INterrupt Code) codes in
input data streams and their meanings;
FIGS. 7 and 8 show the processing flowcharts of programs to be used when a
video screen split command is issued and when a video screen split
terminate command is issued, respectively according to the present
invention;
FIG. 9 illustrates the processing flowchart of a program to be used to
output data to a video data terminal according to the present invention;
FIG. 10 shows a diagram illustrating the processing for scanning an output
data stream and for converting control codes according to the present
invention;
FIG. 11 is the processing flowchart of a program for processing an input
data stream from a terminal according to the present invention; and
FIG. 12 shows a schematic diagram illustrating the processing for scanning
an input data stream, for converting control codes, and for storing the
data in the data buffer for application programs according to the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 and 2 are diagrams illustrating the system network configuration
and the configuration comprising a local machine having the terminal
control function and a video data terminal, respectively to which the
present invention is applied.
The local machine 5 in FIG. 1 has the terminal control function according
to the present invention. More concretely, the function is included in the
subhost OS 17. FIG. 2 shows the connection between the local machine 5 and
the video data terminal 16 illustrated in FIG. 1. The executable
application programs in the local machine 5 and designated as LAAP 1, LAAP
2, LAAP 3, . . . , and LAAP n; which correspond to application programs
18-26 shown in FIG. 1, respectively. For example, the HICOP 18 and DSC
program 19 correspond to LAAP 2, whereas the application program 23
corresponds to LAAP 1. This means that the TSS-AP 9 of the host machine 1
can be regarded as equivalent to the application programs 23-26 of the
local machine 5 by using the HICOP 18 and DSC program 19. The terminal
control function according to the present invention is incorporated in a
communication program 80 of the operating system (to be abbreviated as OS
hereinafter) of the local machine 5. Referring to FIG. 2, it is found that
the video data terminal 16 comprises a display section and a keyboard unit
27. The keyboard unit 27 is equipped with a split command key 32, a cursor
select key 33 for selecting one of two cursors (that is, an upper cursor
or a lower cursor), and a screen split operation terminate key 34
according to the present invention in addition to an alphanumeric and
katakana (the Japanese syllabary) key section 28, a function key section
29, a cursor shift key section 30, and a transmit key 31.
The split screen display operation of the video screen is initiated when
the split command key 32 is pressed on the keyboard unit 27. For example,
the HICOP 18 and DSC 19 which run in the LAAP 2 of the local machine 5 can
use the upper screen 35 area in the video terminal screen, whereas the
measurement data gathering application program 23 which operates in the
LAAP 2 can use the lower screen 36 area. Although the video data terminal
screen is shared between the TSS communication program HICOP 18 and DSC 19
which are regarded as application programs and the application program 23
in this embodiment, it is natural that the display screen of the video
data terminal 16 can be split and commonly used by the application program
23 and another application program, for example, application program 25 in
the local machine 5.
FIG. 3 is a diagram illustrating relationships between control programs and
control tables in the memory of the local machine. In addition to programs
such as the OS 17, HICOP 18, DSC 19, application program 23, and the
communication control program 80, the main memory of the local machine 5
contains a memory area or a buffer LBUF 37 in which the DSC 19 stores the
input/output data of video data terminals in the input/output data stream
format, a memory area or a buffer VBUF 38 in which the application program
23 stores the input/output data of video data terminals in the
input/output data stream format, a memory area or buffer RBUF 39 for
storing the output data streams to be used to generate actual screen
images on the video data terminal screen, and various control tables.
There are provided a control table CRTB 40 for storing the display
operation status of the video data terminal 16, and control tables CTLA 41
and CTLB 42 for respectively storing the screen display information when
the pertinent video screen is split and shared. Control tables DGB 43, DCB
144, and a data buffer DBUF 45 are used to manage the input/output data of
terminals between the HICOP 18 and the DSC program 19.
Since the present invention relates to the communication control program
80, and more specifically relates to control tables CRTB 40, CTLA 41, and
CTLB 42; an input/output area RBUF 39, and buffers LBUF 37 and VBUF 38 for
application programs.
According to the present invention, the communication control program 80
stores the information necessary for split screen display on the video
screen in control tables CRTB 40, CTLA 41, and CTLB 42 according to the
video screen split command information input from the terminal 16 by the
operator. When an input/output request for a video data terminal is issued
thereafter from the DSC program 19 or LAAP 1, the specified split screen
display is performed according to the screen split command information.
Therefore, the read and write requests are issued from the DSC program 19
(LAAP 2) and the application program 23 (LAAP 1) to the communication
control program 80 as indicated by arrows in FIG. 3, and the processing
termination for each request is made by use of a "POST". The read means a
data input from a terminal, the write indicates a data output to a
terminal, and the post designates a processing termination report from the
communication control program 80. Refer to the U.S. application Ser. No.
515,193 for details about the requests and responses between the OS 17 and
the HICOP 18 and between the HICOP 18 and DSC program 19 and relevant
processing procedures.
FIG. 4 illustrates in detail control tables shown in FIG. 3. A data stream
input or output request from or to the video data terminal 16 issued by
the application program LAAP 1 or LAAP 2 to the communication control
program 80 is processed via the input/output areas VBUF 38 and LBUF 37 for
application programs, respectively. Consequently, although the LAAP 2
splits and utilizes the video screen of a video data terminal in the
embodiment according to the present invention, the video screen of a video
data terminal can be split and shared among other application programs,
for example, LAAP 3 to LAAP n as explained hereinbefore.
(1) First the switching control of the split screen operation of the video
screen will be explained.
When a terminal user requests to split the video screen of the video data
terminal 16, the cursor on the screen must be moved upward or downward by
means of the cursor shift key block 30 on the keyboard unit 27 shown in
FIG. 2 to a position at which the screen is to be split. The cursor shift
key block 30 comprises four pushbuttons. When a pushbutton is pressed, the
cursor is moved on the screen to the direction indicated by an arrow on
the pushbutton. Then, the operator need only press the screen split
command key 32.
In this case, a mechanism such as a light pen may be utilized in place of
the cursor shift keys.
FIG. 5 illustrates the input data stream from the video data terminal 16 to
the communication control program 80 in the local machine 5. The input
data stream comprises:
(a) INC (interrupt code) 46 indicating the cause of data input,
(b) Cursor address CSADR 47 on the video screen,
(c) SBA (set buffer address) code 48 indicating that the next data is the
buffer address on the screen,
(d) Buffer address ADR 49 on the screen, and
(e) Input data 50.
The information from the SBA 48 to the data 50 forms a group and this group
may repeatedly appear in some cases.
FIG. 6 is a table listing the interrupt codes (INC) 46 shown in FIG. 5 and
their meanings. When the screen split command key 32 is pressed, a
hexadecimal representation X'80' indicated for the item number 21 in FIG.
6 is stored as the INC. The letter X indicates hexadecimal notation.
FIG. 7 is the processing flowchart of the processing to be carried out by
the communication control program 80 when the screen split command key 32
is depressed.
In the decision processing 150, the data shown in FIG. 5 is examined to
recognize that the INC 46 contains the screen split command code (X'80'),
then the cursor address CSADR 47 is stored in the screen split information
area of CRTB 40 in the processing 151. The screen split information area
comprises management information for splitting and sharing a video screen
as follows:
(a) Identification information of the program to be used,
(b) At least one group of management information comprising the range
information of the screen area available on the actual screen. The screen
range is indicated by use of two buffer addresses corresponding to line
numbers on the video screen. If a screen comprises 24 lines and each line
comprises 80 columns, up to 1920 buffer address can be used ranging from
address 0 to address 1919. The relationship between the line number m and
column number n and the buffer address BA is represented by expression (1)
as follows:
BA=(m-1).times.80+(n-1) (1)
Consequently, if the cursor is placed at a position of column 1 of line 12
to split the screen;
(a) The upper-half area of the screen ranges from line 1 to column 80 of
line 11, that is, the buffer address range is indicated as:
BA.sub.L.sup.U =0
BA.sub.H.sup.U =879
Where BA.sub.L.sup.U is the first buffer address of the upper-half area of
the video screen and BA.sub.H.sup.U indicates the last buffer address.
(b) On the other hand, the lower-half area of screen ranges from line 13 to
column 80 of line 24, that is, the buffer address range is indicated as:
BA.sub.L.sup.L =960
BA.sub.H.sup.L =1919
Where, BA.sub.L.sup.L is the first buffer address of the lower-half of the
video screen and BA.sub.H.sup.L indicates the last buffer address.
When the processing 153 is performed, the identification information of
programs that share the split video screen is obtained. The identification
information contains program numbers and names. In this case, the data
input/output operations between the terminal controller and terminal 16
are carried out via INBUF 44. If the data to be output to the terminal 16
is transferred to RBUF 39, INBUF 44 can be dedicated to data input
operations.
In the processing 154, the connecting relationships between control tables
CRTB 40, CTLA 41, and CTLB 42 shown in FIG. 4 are established and a value
is stored in each field of these control tables. The buffer addresses in
CTLA 41 and CTLB 42 indicate the first addresses, respectively when RBUF
39 is split. The buffer size indicates the length of the pertinent buffer
area, that is, the value of
BA.sub.H.sup.U -BA.sub.L.sup.U +1
is set in CTLA 41; and
BA.sub.H.sup.L -BA.sub.L.sup.L +1
is set in CTLB 42.
The mapping information is used in the data stream input/output operations
to update the value of the buffer address ADR 49 (FIG. 5) following the
SBA code in a data stream when the output data streams of VBUF 38 and LBUF
37 to RBUF 39 are moved to the RBUF 39; or contrary, when the data stream
of the INBUF 44 is distributed to the VBUF 38 and LBUF 37. If CTLA 41 is
assumed to be a control table for the upper-half area of the split video
screen, the BA.sub.L.sup.U and BA.sub.H.sup.U explained before are stored
in CTLA 41; whereas BA.sub.L.sup.L and BA.sub.H.sup.L are stored in CTLA
42.
In the processing 155, the video screen information stored in the VBUF 38
and LBUF 37 is sequentially moved to RBUF 39 and is displayed again. If
only the CTLA 41 is utilized in this case, no image is displayed on the
lower-half area of the video screen.
In the processing 156, the screen split mode flag of the operation status
information in the CRTB 40 is set to be "1" so tht all input/output
operations for the video data terminal thereafter are performed in the
screen split operation mode.
(2) Next, the release operation of the screen split operation mode will be
described.
The release operation of the screen split operation mode is activated when
the screen split terminate key 34 shown in FIG. 2 is depressed by a
terminal user. When the screen split terminate key 34 is depressed, the
INC 46 shown in FIG. 5 is set to the split terminate code X'81' listed for
the item number 22 depicted in FIG. 6. When the communication control
program 80 recognizes this control code, the screen split operation mode
which has been set so far is released and the single screen display
operation is restored. The screen split operation mode release operation
is completed by setting the screen split mode flag of the operation status
information in the CRTB 40 to "0".
FIG. 8 shows the processing flowchart of the processing to be carried out
by the communication control program 80 when the screen split terminate
key 34 is pressed. In the decision processing 157, the data stream
illustrated in FIG. 5 is examined to recognize that the INC 46 contains
the screen split terminate command.
Next, the processing 158 checks whether or not the screen split mode flag
of the operation status information in the CRTB 40 is "1". If it is "0",
the video screen is not operating in the screen split mode, thus the value
in the INC 46 is ignored. If it is "1", the screen usage status
information in the CRTB 40 is checked. The screen usage status information
indicates whether or not the video screen of the terminal 16 is being used
by the application program 23 or the like. It is set to "1" when an
application program issued an open request to use the communication
control program 80 and is set to "0" when a close request thereof is
issued. Therefore, this information is used in the CRTB 40 to indicate
whether or not the CTLA 41 and CTLB 42 are being used. If both of them are
being used, the value of the INC 46 is ignored even if the screen split
terminate kay 34 is depressed. In this case, one of the application
program using the terminal 16 must be terminated before the screen split
terminal key 34 is depressed again.
If at least one of the CTLA 41 and CTLB 42 is not being used, the screen
split operation mode flag in CRTB 40 is set to "0" in the processing 159
to release the screen split operation mode.
Next, the processing 161 or 162 is executed depending on the result of the
decision processing 160. If both CTLA 41 and CTLB 42 are not being used,
the screen image of the video data terminal 16 is cleared in the
processing 161. If at least one of the CTLA 41 and CTLB 42 is not being
used, the contents of the buffer being used, that is, LBUF 37 or VBUF 38
in this embodiment are displayed on the video screen of the video data
terminal 16, thereby resuming the service in use on the video data
terminal 16 and releasing the screen split operation mode.
(3) Next, the operation for transmitting data to a video data terminal will
be described.
To transmit data to the video data terminal 16, a WRITE macro request is
issued to the communication control program 80 after notifying the
addresses of the areas, that is, the VBUF 38 and LBUF 47 in which an
application program 23 (LAAP 1) and the DSC 19 (LAAP 2) which run in the
local machine 5 store output data streams for transmission to the
communication control program 80 as illustrated in FIG. 3.
The application program transfers an output data stream whose size is
equivalent to that of the screen of the video data terminal 16 to the VBUF
38 and LBUF 37. The communication control program 80 forms and transmits
the output data stream whose size is equivalent to that of the screen of
the video data terminal 16 to the video data terminal by use of such
control tables and the like shown in FIG. 4 as the CRTB 40, CTLA 41, CTLB
42, LBUF 37, VBUF 38, and RBUF 39.
After issuing an open request to use the communication control program 80,
the application program performs a data input/output operation for the
video data terminal 16. On receiving an open request from the application
program, the communication control program 80 examines the screen split
operation mode flag of the operation status information in the CRTB 40. If
it is "1", the bit indicating the identification information of the
program to be used is set to "1" in the CRTB 40, thereby allowing the use
of the CTLA 41 or CTLB 42. After this point, the communication control
program 80 can be used until the application program issues a close
request to terminate the use of the communication control program 80.
On receiving a data transmission request from an application program, the
communication control program 80 sequentially fetches the output data
stream from the specified data buffer (VBUF 38 or LBUF 37) and converts
the screen address information included in the data stream string to the
address information on the actual split screen of the video data terminal
16 by using the mapping information stored in the CTLA 41 and CTLB 42
depicted in FIG. 4, then store the resultant data in the actual screen
buffer RBUF 39. The data streams from application programs are stored in
the respective areas of the RBUF 39 corresponding to the ranges of the
split video screen. The split areas of the RBUF 39 are managed according
to the control trables CRTB 40, CTLA 41, and CTLB 42 illustrated in FIG.
4.
FIG. 9 is the processing flowchart of the processing to be carried out by
the communication control program 80 for transmitting data from an
application program. According to FIG. 9, the processing 164 is executed
if the result of the decision processing 163 indicates that the operation
mode is not the screen split operation mode. In the processing 164, the
contents of the data buffer specified by the application program are
output to the video data terminal 16 without changing the address
information.
If it is recognized that the operation mode is the screen split operation
mode, the processing 165 to the processing 168 are executed to prepare the
address conversion for moving the contents of the data buffer specified by
the application program to the RBUF 39. In the example of FIG. 9, the CTLA
41 is used in the processing 165. If the CTLB 42 is to be used, it needs
only to replace the VBUF 38 with the LBUF 37 in the pertinent processing.
In the decision processing 169 to the processing 172, the contents of the
data buffer specified by the application program as explained above are
sequentially checked and the screen information for the split screen is
converted, then the resultant data is stored in the RBUF 39. When all the
aplit areas of the split screen allocated to the application program are
completely used in the RBUF by the decision processing 169, all the
contents of the RBUF 39 are output to the video data terminal 16 in the
processing 173. On the video screen of the video data terminal 16, thus
the transmission data from the application program is displayed in the
upper-half or lower-half of the video screen. This means that the
transmission data from any application program which shares the video data
terminal can be merged and displayed on the video screen.
In this embodiment, although the addresses of the output data streams
stored in the VBUF 38 and the LBUF 37 by the respective application
programs are converted, stored in the RBUF 39, and are output to the video
data terminal 16; the RBUF 39 may not be necessary if the data is
transmitted to the video data terminal 16 immediately after the
communication control program 80 performs the address conversion for the
output data streams of the VBUF 38 and LBUF 37.
FIG. 10 is a diagram illustrating the concept of the processing for
converting the screen address information shown in the processing 171 of
FIG. 9. This processing is called a mapping conversion processing.
Referring to FIG. 10, the output data stream in the data buffer DBUF 45 to
be passed from the HICOP 18 to the DSC program 19 contains the display
data string following such screen control information as the command code
(CMD), control byte (CB), set buffer address (SBA) code, buffer address
(ADR), field heading (FH), and define field character (DFC).
The DSC program 19 inputs the data stream of the DBUF 45. If the CMD 76
indicates a data transmission, the output data stream from which the CMD
76 is removed is stored in the application program data buffer LBUF 37,
then a data transmission request is issued to the communication control
program 80. The data items such as the control characters in the data
stream of the LBUF 37 are suffixed, for example, as CB.sub.2, ADR.sub.2,
and DFC.sub.2 only for the purpose of explanation. They are identical to
the CB, ADR, and DFC, respectively in the DBUF 45.
On the other hand, the application program 23 (LAAP 1) stores the output
data stream in the application program data buffer VBUF 38 and issues a
data transmission request to the communication control program 80.
In the mapping conversion processing 171 of the communication control
program 80, when an SBA code is detected while scanning sequentially the
output data streams in the VBUF 38 and LBUF 37 by use of the control
tables CRTB 40, CTLA 41, and CTLB 42, the next data string is assumed to
be the buffer address on the video screen and the screen address
information (ADR.sub.1 and ADR.sub.2) is converted into the ADR.sub.1 ' 77
and ADR.sub.2 ' 78 based on the mapping information in CTLA 41 and CTLB
42, then the resultant data is stored in the RBUF 39.
The screen address conversion for obtaining ADR.sub.1 ' and ACR.sub.2 ' is
carried out as follows. In this case, it is assumed that the CTLA 41 is
used for VBUF 38 and that the mapping information in the CTLA 41 comprises
the BA.sub.H.sup.U and BA.sub.L.sup.U. Further, the CTLB 42 is used for
the LBUF 37, and the mapping information in the CTLB 42 comprises the
BA.sub.H.sup.L and BA.sub.L.sup.L.
(a) Conversion by use of CTLA 41
The upper-half of the video screen is used in this case, thus the
BA.sub.H.sup.U is the basic value for the buffer address conversion. That
is, if the ADR.sub.1 of the VBUF 38 is less than the lower-limit address
BA.sub.H.sup.U of the upper-half of the video screen, the address
conversion is not necessary and the value of the ADR.sub.1 is stored in
the DR.sub.1 ' 77.
If the ADR.sub.1 is equal to or greater than BA.sub.H.sup.U, the data
related to the ADR.sub.1 is displayed in the lower-half of the video
screen of the video data terminal 16. Therefore, the ADR.sub.1 ' 77 is
converted to be equal to the value of
ADR.sub.1 -BA.sub.H.sup.U
so that the output data stream from the VBUF 38 originally prepared to be
displayed on the overall screen is changed to be displayed only in the
upper-half of the screen.
(b) Conversion by use of CTLB 42
The lower-half of the video screen is used in this case, thus the
BA.sub.L.sup.L is the basic value for the buffer address conversion. If
the ADR.sub.2 of the LBUF 37 is equal to or less than the BA.sub.L.sup.L,
the data related to ADR.sub.2 is displayed in the upper-half of the video
screen of the video data terminal 16. Therefore, the ADR.sub.2 ' 78 is
converted to be equal to
ADR.sub.2 +BA.sub.L.sup.L
and stored in the RBUF 39. If the ADR.sub.2 is greater than the
BA.sub.L.sup.L, the ADR.sub.2 is used as the ADR.sub.2 ' 78 and is stored
in the RBUF 39.
As explained above, the data streams in the VBUF 38 and LBUF 37 are merged
(composed) in the RBUF 39 and are output to the video data terminal 16.
Although the data is transferred from the LBUF 37 or VBUF 38 to the RBUF 39
in reply to a data transmission request issued from an application program
to the communication control program 80 in the embodiment of the present
invention, the data transfer from the LBUF 37 or VBUF 38 to the RBUF may
be further carried out in reply to a special control code input from the
video data terminal 16. If this function is provided additionally, the
operation can conveniently input the special control code to set the
screen split operation mode. In this case, the data streams stored in the
LBUF 37 and VBUF 38 are displayed on the screen of the video data terminal
16 in the screen split operation mode.
(4) Next, the operation to be executed by an application program to receive
data from a v:deo data terminal 16 will be explained.
To receive data from the video data terminal 16, an application program
issues a READ macro request to the communication control program 80. The
terminal user inputs data thereafter from the keyboard unit 27 depicted in
FIG. 2 and presses the transmit key 31. Then, the input data stream shown
in FIG. 5 is written in the INBUF 44 illustrated in FIG. 4.
The communication control program 80 examines the CSADR 47 of the input
data stream in the INBUF 44. The application program related to the input
data can be identified depending on whether or not the value of the CSADR
47 is less than the BA.sub.H.sup.U stored in the screen split information
of the CRTB 40. This means that it is determined whether the control table
CTLA 41 or CTLB 42 is used.
In the next step, the ADR information in the input data stream is converted
if necessary by use of the mapping information in above-mentioned control
tables, then the input data stream is stored in the LBUF 37 or VBUF 38.
FIG. 11 is the processing flowchart of the processing to be carried out by
the communication control program 80 to receive data. If the result of the
decision processing 181 indicate that the operation mode is not the screen
split operation mode, the processing 182 is selected to perform the
ordinary processing.
Next, whether the data is input from the upper-half or lower-half of the
video screen is determined by the decision processing 183. Then, the
processing 184 or 185 is executed depending on the result of the decision
processing 183. The difference between the processing 184 and the
processing 185 is whether the CTLA 41 or CTLB 42 is used.
In the processing 184 and 185, the value of the split-screen address in the
input data stream is converted to the screen address for displaying the
data from each application program on the screen in the single screen
mode. This processing is called an inverse mapping conversion processing.
FIG. 12 is a schematic diagram illustrating the concept of the processing
for converting the screen address information shown in the processing 184
and 185 of FIG. 11.
Next, the processing for storing an input data stream in the VBUF 38 by use
of the control table CTLA 41 will be explained. The processing for storing
an input data stream in the LBUF 37 can also be performed according to the
same idea. Referring to FIG. 4, since the video screen image is split and
input thereafter, the input data stream obtained by an input operation
from the video data terminal 16 cannot entirely fill up the buffer VBUF 38
whose size is equal to that of the screen of the video data terminal 16.
On the other hand, the application program LAAP 1 has been designed so
that the input data stream length corresponds to the size of the buffer
VBUF 38, that is, the size of the screen of the video data terminal 16.
Consequently, the processing of a READ macro request from an application
program is completed by storing the input data stream from the video data
terminal 16 in the VBUF 38 at least two times. That is, the value of the
ADR.sub.1 ' 49 can be used for the ADR.sub.1 " for the first input data
stream from the video data terminal 16. This is because the first input
data from the video data | | |
