		   README file for xvt 1.0
		   -----------------------

Xvt is an X terminal-emulator that is designed to be more or less
compatible with xterm while using much less swap space.  It is mainly
intended for use at sites which use large numbers of X terminals but
may also be useful on single workstations that are short of memory.  On
a SPARCstation, an initially invoked xvt uses about 1/3 megabyte of
swap while xterm uses about 1.3 megabytes (obtained by running pstat
rather than ps which seems to give unreliable size figures on SPARCs).
The main way that xvt achieves its small size is by avoiding the use of
the X toolkit.

The current version of xvt is our default X terminal emulator and has
been used for eight months by students, computing support staff and
service users and so is fairly well tested.

Supported architectures
-----------------------

Sun SPARCStation running SunOS 4.1.?.  There should be not any real
problems in porting xvt to other platforms although the tty
initialisation code may need changing on hosts that only support BSD
sgtty terminal configuration.

Xterm features not supported
----------------------------

 - Tektronix 4014 emulation

 - Session logging

 - Pop-up menus.  The only one of xterm's popup menu commands that is
   provided in xvt is displaying and hiding of the scrollbar and this
   is done simply by pressing any mouse key in the window with the
   CONTROL key held down.

 - Coloured text cursors

 - Toolkit style configurability.  In particular, xvt does not allow
   the user to remap the mouse or keyboard keys.

 - Vt100 graphics characters - this will be remedied in the next version.

Major xterm features that are supported
---------------------------------------

 - VT100 emulation.  Most of the main escape sequences are supported -
   certainly all those used by the standard screen based UNIX
   applications.

 - Lines that scroll off the top of the window are saved can be
   scrolled back with a scrollbar.

 - Text selection and insertion including double and triple click for
   words and lines.

Other differences between xvt and xterm
---------------------------------------

 - Xvt has a couple of additional enquiry escape sequences:

   ESC[7n - causes xvt to respond with the name of its X display in a
	    form that can be used to initialise the DISPLAY environment
	    variable.  If this is done in a user's .cshrc file it
	    provides a way to automatically update DISPLAY after an
	    rlogin.  Something like the following should work if the
	    initial ^[ in the echo command is an ESC character:

	    if(!($?DISPLAY)) then
		if($?term) then
		    if($term =~ xterm*) then
			stty -echo >/dev/tty
			echo -n '^[[7n' >/dev/tty
			setenv DISPLAY `line </dev/tty`
			stty echo >/dev/tty
		    endif
		endif
	    endif

   ESC[8n - causes xvt to respond with a hex encoded copy of the server's
	    magic cookie which can be used to update a user's .Xauthority
	    file.  We have a program to do this which could be made available
	    if anyone is interested.

Known Bugs
----------

 - xvt does not know about transferring selections in installments and so
   making large selections or trying to insert large selections will
   fail.  The maximum selection size supported is server dependent but
   seems to be a little under 64k on all our servers.

 - On a heavily loaded machine, a text insertion (middle mouse button)
   quickly followed by a keyboard key press will sometimes be interpreted
   in the wrong order.

 - xvt does not look in all the approved places for its X resources.
   It does, however, work correctly with resources that have been
   loaded into the server using xrdb

Building and installing xvt
---------------------------

To build xvt, simply type 'make'.

To install xvt, you should edit the MANDIR and BIN pathnames in the
Makefile and then type 'make install' as root.  When installed for
general use, xvt needs to belong to root and have the setuid flag set
so that it can make entries in the /etc/utmp file.

Please send bug reports and WIBNIs to:

John Bovey
Computing Laboratory
University of Kent at Canterbury
Canterbury
Kent
UK

email: jdb@ukc.ac.uk
