RU1825427C - Device for connection computer to phone line - Google Patents

Abstract

Usage: for organizing communication between personal computers of the IBM PC class via telephone lines using modems. The purpose of the invention is to increase the efficiency of the device by increasing the exchange rate and the reliability of the transmitted information. The device comprises an input / output control unit, a buffer data memory, an address decoder, a signal generator for closing and opening the telephone line, an analog-to-digital converter, a digital-to-analog converter, and a call indication unit. 1 ill.

Description

The invention relates to the field of computer engineering and can be used to organize communication between personal computers of the IBM PC class via telephone lines using modems.

The aim of the invention is to increase the efficiency of the device.

The drawing shows a functional diagram of the device.

The device comprises an input / output control unit 1, a data buffer 2, an address decoder 3, a telephone line closure and open signal generator 4, an analog-to-digital converter 5, a digital-to-analog converter 6, a call indication unit 7.

. The device operates as follows.

The signals of the microprocessor control the device for interfacing.

Block 1 is reset via the RESET DRV bus, thereby preparing the device for operation. Buses DO-D15 transmit information from the processor to memory 2 or vice versa. Tires are bidirectional. Data transmission is controlled by signals nq to the IDR buses - reading from the I / O port, which reads information from memory 2 to the processor or IDW, which writes information through block 1 to memory 2.

The device uses the principle of encoding (modulation and demodulation) of the transmitted and received information by a pseudo-sinusoidal signal, implemented in software, in which the main parameter of the modulating sinusoidal (Л

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The signal is its period. This parameter is entered into one of the registers of block 1. In this case, up to 150 different operating frequencies can be used in the system (at each time point, 2–16 frequencies can be used simultaneously), which allows one frequency to encode from one to four bits . The modulation method used allows transmission at a rate of 1200 to 6600 bps.

It should be noted that since the signals are tracked along the edges, the transmission and reception are inherently synchronous, which positively affects the characteristics of the system as a whole, such as the reliability and reliability of the transmitted information

When transmitting information from the processor to the telephone line, data is written from the processor's memory to memory 2. At the same time, the port for transmitting information using the decoder 3 via the address buses is indicated. In addition to the address, an AEN address enable signal is also generated to provide direct access to the processor memory. Information from memory 2 enters block 1 to register A, the first three bits of which are used to form the modulation frequency of the signal (sinusoidal signal). The modulated signal is fed to a digital-to-analog converter 6. From where, in the form of code packets, it is sent to a telephone line. The device for interfacing is galvanically isolated from the telephone line by means of a transformer, which ensures the independence of the interference in this line arising from power surges. To generate a call to the line, register C of block 1 is used, which controls the formation of a closing and opening signal by the telephone line by means of shaper 4. In this case, a single signal is supplied to the corresponding bit of register C and the relay in shaper 4 is turned on, which leads to shorting the transmission wire of the communication line.

When receiving information from the telephone line, the signal is converted from the communication line to a digital signal by the converter 5 using the register B of block 1. The start of reception is indicated by block 7, the signal from which turns on the register B of block 1. Information from the communication line through register B of block 1 is accumulated in memory 2 and then to the address indicated

decoder 3 is read into the processor memory.

Thus, a device for interfacing a computer with a telephone line provides the following functions:

short circuit, open telephone line,

indication of ringing level,

conversion of three-bit values into output signal levels,

conversion of the input signal to single-bit values.

The performance of these functions allows reliable data transmission under conditions of a high level of interference and a low level of a useful signal, which, in turn, will allow data exchange in a plurality of dispersed computers.

Claims (1)

The claims A device for interfacing a computer with a telephone line of communication, comprising a control unit for water supply to the house, the information input / output of which is connected to the first input / output of the buffer data memory, the second input / output of which is connected to the information input / output devices whose address output is connected to the input of the address decoder, the output of which is connected to the address inputs of the data buffer and the input-output control unit, the address output of which is connected to the address output of the device, digital-to-analog and analog-to-digital conversion The callers, the output of the digital-to-analog converter and the input of the analog-to-digital converter are connected to a telephone line connected also to the input of the call indication block, the input of writing data to the data buffer memory, the input for reading data from the buffer data memory, and the device address resolution input are connected to corresponding inputs of the I / O control unit, a data buffer, and an address decoder, characterized in that, in order to increase the efficiency in operation of the device by increasing the speed of exchange and reliability of the transmitted information, a signal generator for closing and opening the telephone line is introduced into it, the information output of the I / O control unit is connected to the input of the digital-analog converter, the information input is connected to the output of an analog-digital converter, the output of the call indication unit is connected to the control input of the control unit input-output, the control output of which connected to the input of the shorting and breaking signal generator of the telephone line, the output of which is connected to the telephone line. - IB I LA MO-S4 / 9 AND, To telephone At / me