TTLINK (Program) TTLINK is a program that lets you interact with another computer over an assigned DEC-20 TTY line. TTLINK is useful with autodialers, hardwired EIA/RS-232 serial connections between processors, and any other arrangement whereby you can assign a DEC-20 TTY port that is connected in some way as a terminal to another system. Once the connection is established, all characters are passed through to the remote host until you type the escape character, at which time TTLINK treats the next character you type as a special command, the most important of which is "C", which gets you back to the local DEC-20. * Form: ttlink or ttlink connect line /switches * Commands: CONNECT line /switches LINE is an octal TTY line number; optional SWITCHES are: /DUPLEX:dup Set to FULL if the remote host echos, or HALF if it does not. The initial default is FULL. /PARITY:par PAR can be one of NONE, MARK, EVEN, ODD, or SPACE. Parity initially defaults to NONE. /LOGFILE:name Keep a transcript of the remote session in file NAME. /ESCAPE:n Set the escape character; the default character is CTRL-Y (octal 31). N is the octal value of an ASCII control character to be used as the escape character: for example, 1=CTRL-A, 32=CTRL-Z. The escape character is used in conjunction with certain other commands: see the Single Character Commands section below. /SPEED:n Tell TTLINK the speed of the port, and enable BREAK simulation (see below). The speed is the baud rate, typically 300, 1200, 1800, 2400, 4800, or 9600. /BREAK-NULLS:n For adjusting BREAK simulation (see below). EXIT Exit from TTLINK. If you CONTINUE TTLINK, the duplex, parity, and escape character settings remain the same. HELP Print a help message. STATUS Display the current line number, duplex, escape character, parity, and logfile. * Single Character Commands: While connected to the remote system, you may regain the attention of the local TTLINK program by typing the escape character (CTRL-Y unless you define it otherwise). TTLINK waits for you to type another character, one of the following: ? Print a quick list of available escape commands. C Close the connection, return to the DEC-20. You can resume the connection with another CONNECT command, or by continuing TTLINK. P PUSH to a new Exec. Return via the POP command. Q Quit logging. R Resume logging. S Show status of connection: line, escape character, duplex, parity, and logfile. B Send a simulated BREAK signal (see below). CTRL-Y Typing the escape character twice in a row sends the escape character to the remote host. Initial defaults for CONNECT are FULL DUPLEX, escape character = CTRL-Y, PARITY NONE, and no logging. There are no initial defaults for line or logfile. Defaults for subsequent CONNECT commands become whatever was specified in the most recent CONNECT command. All settings are established in the CONNECT command. Command line arguments (ccl, rescan) are accepted. Thus, TTLINK is easily started from another program with an RSCAN argument, and the superior can be in control of what the settings are. * Sending a BREAK signal from the DEC-20: Sending a BREAK signal to the remote host can be a tricky business, because the DEC-20 supplies no function to do this. Therefore, TTLINK simulates a BREAK by temporarily setting the speed of the line to 50 baud, sending several null (ASCII 0) characters, and then setting the speed back to what it was. But TTLINK has no way of knowing wath the speed was unless you tell it, because TOPS-20 does not remember the speed of a remote (modem-control) line. Therefore, if you intend to send a BREAK signal to the remote host, you must first use the following switch on the CONNECT command: /SPEED:n The argument is a decimal number which is the current speed of the line, such as 300 or 1200. If you omit this switch, TTLINK will not try to send a BREAK. You may transmit a BREAK by typing the BREAK key on your terminal ONLY IF YOU ARE DIRECTLY CONNECTED TO THE SYSTEM WHICH IS RUNNING TTLINK (if your are connected through a network, the BREAK generated by your terminal will not get through to TTLINK). In any case, you can always tell TTLINK to send a BREAK by typing your escape character followed by the letter B. If you find that your BREAK signal is not recognized correctly on the remote system, you may have to adjust the number of NULL characters that are sent; the following CONNECT command switch allows you to do this. /BREAK-NULLS:n The default number of NULLs transmitted is 3. If that is not enough, the remote system may not react. If that number is too high, the remote system may sense two or more BREAKs. [End of TTLINK.HLP 17-Nov-83]