JPS58191032A - Terminal device for transfer system of bidirectional data - Google Patents

Abstract

PURPOSE:To simplify the transfer of signals between different code systems, by connecting a block containing a code system converting part and a code system discriminating part to a keyboard of a system which performs a bidirectional transmission. CONSTITUTION:A connector 20 is connected to a keyboard of a terminal device which can transmit data in both directions. Pins P1-P3 are connected to an earth line as well as to power supply lines of -5V and -12V, respectively. A level 0 or 1 is applied to a pin P4 from the keyboard of the main body in accordance with the type of the keyboard. The level is set at 1 with 7 bits/words and set at 0 with a special keyboard of 12 bits, respectively, for example. A pin P5 functions as an input terminal, and a pin P6 is set at 0 with 75B transmission rate and at 1 with 1,200B, respectively. Whether or not the bit code is converted 23 is switched 24 by discriminating 21 the voltage of the P4. Then the voltage of the P6 is discriminated 22 to vary the frequency of a clock 25, and the code is discriminated at a code discriminated part 26. In such a way, the data can be transferred simply between different code systems.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a terminal device for a two-way data exchange system that transmits requested data to each home via a telephone line.

An information system that connects a home television receiver to a data bank via a telephone line and searches for desired information while talking to the data bank using keyboard operations and an index displayed on the television receiver. ``Videotex'' or ``View Data'' has been developed. An alphanumeric keyboard is usually used as a means of conversation, and for example, in the system with the service name 1 Press Still in use in the UK, the BPO standard (Br
itish Po5t Office 8tandar
d) The keyboard is connected to the terminal device in each home.

Each terminal device includes a serial printer in addition to the keyboard.
An output device or recording/playback device such as a video printer or a cassette tape recorder is connected. Conventionally, in order to control these output devices, CRTs, etc. in each terminal, it is necessary to connect to the terminal another input device called a keypad, which has function keys such as start printing and start recording. Therefore, the control operation of the terminal system is complicated, and the cost of the entire system is increased.

It is an object of the present invention to maintain convertibility with conventional systems and to enable keyboards of different code systems having various function keys to be connected to a terminal.

The present invention will be described below with reference to Examples. Figure m1 is a block diagram of a terminal device of an image information system to which the present invention is applied. This terminal device is connected to a computer center (data bank) through a telephone port 11 (1)'). Information from the databank is transmitted to the modem (2+(MOD)
The data is transferred to the central processing unit @CPU (4) through the data control circuit (3) and the data control circuit (3), and written to the random access memory RAM (5).

The IJI image data stored in the video RAM (5) is sequentially read out, converted into characters or figures by a character generator (6), and displayed on the CRT (7). Synchronization signals for the CRT (7) and timing signals used throughout this terminal are generated by the timing generator (8).
) is formed.

A keyboard is used to access the data bank, and the information is input via the telephone line (1) via the input port Korean data control circuit (38 modem (2)).
from there to the computer center.

A cassette control circuit 0 and a printer control circuit 9 are connected to the CPU (4) via an output port a2, and these control the cassette recorder and printer (1Q).Data processing within the terminal The time base required for is formed by the timer a force,
In addition, the calculation control of the system by CPU (4) is performed by R.
This is done based on a program written in the OMQ barrel. As will be described later, an encoding table for converting encoding systems for keyboards of different standards is written in the OM a8.

Three types of keyboards OQ can be connected to the terminal device of this embodiment. One of them is the alphanumeric keyboard (
It has a code system similar to ASCII and has a transmission rate of 7.
The input data from these two keyboards is 7 bits/word.

Furthermore, a sixth special keyboard of another format can be connected to this terminal. This keyboard is a 12-bit/word alphanumeric keyboard based on a portable data transmission ICi that is often used in remote control systems for television receivers and VTRs.
Operation instructions (commands) for printers and cassette recorders
It has many function keys for This keyboard can be manufactured at an extremely low cost using a portable remote control IC, and its hardware is compatible with the Captain System, an image information system in Japan.

As mentioned above, when an alphanumeric keyboard (75 baud and 1200 baud) that conforms to the BPO standard is connected to this terminal, the keyboard itself cannot command the operation of a printer, cassette recorder, etc.
control commands) cannot be given,
You will also need to connect a keypad for these commands.

On the other hand, if you use the 12-bit special keyboard mentioned above,
There are function keys for commands, so
No need to connect a separate keypad.

Figure I@2 is an isometric block diagram of the keyboard input converter in the terminal device of this embodiment. The main functions of this block diagram are actually achieved by the microcomputer program W in the system shown in FIG.

In FIG. 2, the connector (A) of the terminal device is connected to w, and the keyboard aO in FIG. 1 is connected. The first to sixth pins P1 to P3 are used for a ground line and +5V and -12V power lines, respectively. #! The 5th pin Ps is a data input terminal. The fourth pin P4 is given a voltage of logic level @o"t or '1" from the keyboard α, depending on the type of keyboard, and the voltage of the above-mentioned BPO standard keyboard (7
For example, when a 12-bit special keyboard is connected, it becomes ``1'', and when the above-mentioned 12-bit special keyboard is connected, it becomes @0''.The 6th pin P4 also has a BPO standard transmission rate of 75 baud. Logic level @ according to keyboard and 1200 baud keyboard
A voltage of 0'' or @1'' is applied.

The voltage at the fourth pin P4 of the connector (7) is determined by a voltage determining circuit Qυ, and the changeover switch (2) is switched based on the determined output. Further, the voltage at the sixth pin P6 is determined by a voltage determining circuit (c), and the frequency of the system clock generator (2) is switched based on the determined output.

When a BPO standard keyboard is connected to this terminal, the output of the voltage discrimination circuit (2υ becomes 11" and the changeover switch (c) is connected to the contact (24kl) side. The difference in transmission rate (75 baud/1200 baud) is determined by the voltage discrimination circuit 4, and a system clock with a frequency corresponding to each rate is output from the clock generator (c).Accordingly, a BPO standard keyboard is connected. When the input data is transferred from the fifth pin P5 of the connector (A) to the selector switch (C).
The system code discrimination unit (E) receives the data through the contact (24b), and the system code discrimination data is transmitted to the data bank via the modulator/demodulator (2) and through the telephone line (1). Alternatively, it is led out into the terminal to control each part (CRT or printer) in the terminal system.

When the 12-bit special keyboard is connected, the output of the voltage discrimination circuit QI becomes ``0'' and the changeover switch Q4 is switched to the contact (24m) side. The input data from the fifth bin P5 is
After the 12-bit to 7-bit code converter converts the code into a code system based on the 7-bit ASCII code, the switch c! 4) and is sent to the code discrimination section (c). This code conversion C'i% is actually the encode table and CP written in ROMQ8 in FIG.
This is executed under the control of U (4).

As mentioned above, this 12-bit keyboard is a T9 keyboard.
It is equipped with function keys for control instructions (commands) for the terminal output device, etc. Therefore, it is necessary to add new codes that were not included in the codes of the conventional BPO standard keyboard.

BPO for this newly added command code
The distribution in the standard code table is as shown in the following code table.

Basically, blank spaces in the code table are assigned to command codes, but there is a transmission control code that is only used between the computer center, which is a data bank, and terminals in each home. This is the code for letters, numbers, and symbols that are duplicated between the computer and the terminal (specifically, between the keyboard and the C'PU).

Also, the 0.1th column in this table is assigned to the transmission code,
Of these, cursor/caliber 7 (Curs
or CR; code “QD”, cursor-line feed (Cursor L F; :]-do l″OA
”), Curs) L/ 11 horizontal tab (Curs)
or HT ; code ``09'') are codes used for format control, and these codes cannot be used redundantly between the keyboard and the terminal.

As shown in brackets [ ] in the table, the command codes given to the output device by the function keys of the 12-bit keyboard are 101”...ON LINE... Line "1A" that connects... Offline (OFFLI)
NE)・・・・・・Cut 111 times @10”・・・・・・
...Print (PRINT) --- Video printer on "02" ... Serial print (8PRINT) ... Serial printer on @15
”・・・・・・Cheapletsk (TAPE clothes)-
・・Tape recorder recording @16”・・・・・・Tape replay (TAPE)lJliiPLAY)・・
・Tape recorder H-113”...Pass door (S customary)...There are memories in the memory.For these command codes, use the blank spaces in the code table, or It is used redundantly with transmission control codes other than format control codes.For example, the code @02'' is used between the data puncture and the terminal as the start of text (8
TX, the first code of data), and between the keyboard and terminal, it is used to display the command code to turn on the serial printer, and between the keyboard and terminal, it is used to display the memory contents that are not displayed. It is used as a command).

When a 12-bit special keyboard is connected to the terminal as described above, the code converter (c) in Figure 2
The input data is converted into 7 and 7 data according to the ASCII code according to the above code table, and then the input content is discriminated by the code discriminator sg8. When you operate the function keys on this keyboard, code conversion from 12 bits to 7 bits is performed according to the table above, but even if the converted code overlaps with the transmission control code, these codes will be converted between the keyboard and the terminal ( Since it is used only with the code discriminator (261 or CPU) shown in FIG. 2, there is no possibility of a malfunction caused by confusion with the transmission control code when sending data from the data bank through the telephone port +1!.

As described above, the present invention detects a discrimination signal from a terminal that receives data from the keyboard, and selects one of the keyboards based on this detection output in order to connect keyboards with at least two different code systems to a terminal device. It is designed to convert one code signal into another keyboard code system.

Therefore, according to the present invention, keyboards with other code systems can be connected to the terminal device while maintaining compatibility with conventional systems. becomes possible to use.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a terminal device in each home of an image information system to which the present invention is applied, and FIG. 2 is an isometric block diagram representing the function of the keyboard input code converter of the device in FIG. 1. be. In addition, in the symbols used in the drawings, (1)・・・・・・・・・・・・・−・Telephone line (2)
・・・・・・・・・・・・Modulator/demodulator (4)...
・・・・・・・・・・・・CPU(6)・・・・・・・・・
...Character generator (7)...
・・・・・・・・・・・・ CRTQO・・・・・・・
・・・・・・・・・Keyboard Q5・・・・・・・・・・
...Cassette recorder a6)...
・・・・・・Printer (a)・・・・・・・・・・・・
... Connector (2a (221-......
・Voltage discrimination circuit (c)・・・・・・・・・・・・・・・
12-bit → 7-bit code conversion section (c)...
......This is a code discrimination section. Agent Masaru Saturn〃 Yoshio Tsuneko I Toshiki Sugiura

Claims (1)

[Claims] In a terminal device of a bidirectional data exchange system capable of connecting keyboards of at least two different code systems,
A means for detecting a discrimination signal from a terminal receiving data from the keyboard, and a converter for converting a code signal from one keyboard into a corresponding code system of the other keyboard based on the detection output, A terminal device for a two-way data exchange system that performs code discrimination of a code signal from a section and sends data to the outside or controls operations within the terminal system.