tandem Command

The tandem BASIC program links the current port to another process. Any input or output to either screen affects both screens.

The port initiating the tandem command is the master. The process being attached is the slave or target. If the slave process is a phantom process, the output from the phantom is redirected to the master. The target device (the one attached to the slave) must be available on the specified port. It cannot be already attached to another process.

A hot key sequence disconnects the link. The default hot key sequence is Esc, X. If an esc-data has not been issued previously, the process issues it automatically, to prevent getting locked out from being able to suspend tandem.

NOTE	The tandem command requires sys2 privileges.

Syntax

tandem port.number {(options}

Parameter(s)

options	d	Designates the sequence of (up to four) characters to terminate tandem mode. Each character is provided in its hexadecimal equivalent of its ASCII value. Each character is separated by a comma. For example, d/41,42,43,44, indicates that an "ABCD" disconnects the link. The first two characters of the termination sequence must be different. For example, it does not accept "d/2b,2b,2b" (+++), but it accepts "d/2a,2b,2b" (*++).
	f	Turns off the ability to tandem on the current port. This keeps others from being able to tandem the current port. Specifying the port number allows turning off tandem on another port.
	n	Turns on the ability to tandem on the current port. This gives others the ability to tandem the current port. NOTE—This option cannot be used with the u option. Specifying the port number allows turning on tandem on another port.
	s	Suppresses the message when the process terminates. If this is used with the d option, the s option must precede the d option.
	u	Unconditionally turns off tandem when used with the f option.
	x	Terminates tandem on the target device number. NOTE- When tandeming from a d3tcl session, CTRL+X does not terminate the tandem. In such a case, you must type CTRL+[ followed by an X to terminate the tandem.
	y	Sets the notify option. When tandem is started or terminated on the process, the command specified for the tdmon or tdmof signals the trap TCL command.

CAUTION

If the master and slave processes are different types of screens, or are using different emulations or terminal types, the output to the master screen may be garbled.

If the current task has esc-level in effect, tandem automatically issues an esc-data, so that it can be terminated by Esc, X sequence. It does not, however, reset the esc-level upon termination—it must be manually re-executed to restore to its previous state.

When a process pushes a shell to UNIX while being issued a tandem by another port, theoretically, the D3 process is suspended by UNIX, therefore the input from the master is not processed by the D3 process until it is reactivated by UNIX.

Example(s)

Attaches the current process to port 13.

tandem 13

Attaches to port 3 and sets the hot key sequence to *++.

tandem 33 (d/2a,2b,2b

Enables ability to issue tandem on the current port.

tandem (n

Unconditionally disables tandem capability on port 42.

tandem 42 (uf

Terminates tandem on port 13.

tandem 13 (x

The tcl command can be used to enable tandem on another port.

tcl 42 bob tandem (n

tandem 42