The command to communicate with another user is called TALK.  It makes
everything that either one of you types appear on both terminals.

(Note: If you want to know about the TALK program on the Altos, READ DMCHAT,
which describes both Alto DMCHAT and Alto TALK.  The writeup below is for
the TALK command on SAIL, which is completely different from Alto TALK.)

The argument to TALK is either the programmer name of the person you want
to talk to, the device name of the terminal you want to talk to, or an
ARPAnet address.  For example:

	TALK MRC
	TALK TTY34
	TALK RMS@AI  (% is legal as a host name delimiter also).

The command may fail for any of the following reasons:

. user not logged in (use MAIL)
. user logged in more than once (use a terminal instead of a user spec)
. user gagged or (for ARPAnet TALK) refusing links (use MAIL)
. the ARPAnet site is unreachable or does not support network linking

When you are in a (local) talk ring, what you type goes only to the
terminals in the ring, not to the monitor or a user program.  To leave
the talk ring, type [CALL] (control-C from non-displays).

TALKing to local users does not run a program; hence the core image is
preserved.

TALKing to network users runs a program.  To leave network talk, type
<CONTROL><META>[LF] (control-Z from non-displays).

It is considered antisocial to use the TALK command to establish
communication with strangers.  A better way is the SEND command, which
will send a message to a user but does not interfere with his work.
For this reason, the TALK command requires that you be logged in.  If
you don't have an account, you can use SEND to request the user TALK
to you.  Type "HELP SEND" for more info.