Changes from release 1.5 to release 2.0

   General:
    
     o  The build and install process has been improved significantly (see
	file INSTALL)
     o  Added a new directory "config" that holds the system-specific
	configuration files and the site-file
     o  Added a build shell script and a unified Makefile to all
	directories; "build" creates the ``real'' Makefiles containing
	system- and site-specific details during the make process
     o  Added install, lint, clean, and distclean targets to all
	Makefiles
     o  Placed files that are needed during runtime (dynamically loadable
	object files, Scheme files, the interpreter itself) into separate
	directories; added "make install" to put files there

     o  Simplified porting Elk to new systems (assembly language support
	and a stack-extending version of "alloca" are no longer required)
     o  Tested on several new systems (IBM RS/6000, HP9000/700, SGI,
	Sony; see the file MACHINES)

     o  Placed new files CONTRIBUTORS, MIGRATE, and TODO into the toplevel
	directory of the distribution
     o  Added a directory "util" that contains tools to simplify porting
	Elk to new environments and other utilities that are useful on
	some systems
     o  Added a directory "scripts" that holds the shell scripts used
	to link instances of the interpreter and extensions.
     o  Removed "stk" directory with test programs (no longer needed)

     o  Added ANSI C prototypes and C++ "extern C" to all include files

   Interpreter kernel:

     o  Placed include files into a separate directory (include)
     o  Reorganized the source files (separate source files for different
        a.out formats and different dynamic loading mechanisms)
     o  Changed the way new Scheme objects are allocated to support the
	generational garbage collector (not yet present in Elk)
     o  Rewrote the code implementing continuations to support full
	call/cc on all machines
     o  Fixed tail recursion optimization
     o  Added support for POSIX signals (as alternative to BSD reliable
	signals)
     o  Removed several artificial limitations (such as max. number of
	before-GC and after-GC functions and statically GC-linked objects)
     o  Removed code that depended on max. number of open files per process
     o  Added bi-directional ports (input-output-ports); new primitive:
	open-input-output-port
     o  New primitive: port-line-number
     o  Reader now prints line number on syntax error
     o  Max. length of a pathname is now determined correctly (using the
	POSIX incantations if applicable)
     o  Added code to support dynamic loading under HP-UX (src/load.shl.c)
     o  Added code to call extension finalization functions and C++
	destructors on termination
     o  Fixed and improved the code to call extension initialization
	functions and C++ constructors on startup or when loading
	extensions
     o  Improved the mechanism to suppress initialization of statically
	linked extensions on startup ("dont_init_if_name" in config/site)
     o  Can use ANSI "atexit" as alternative to redefining "exit"
     o  Added option -p to specify load path
     o  Scheme file "initscheme" is now loaded before the toplevel is
	loaded
     o  Changed "rand" to use rand() if random() isn't there
     o  re-entrant-continuations? primitive is no longer needed (returns
	always #t now)
     o  Added a general mechanism to register termination functions for
	individual objects (e.g. to close files on GC); see src/terminate.c
     o  linkscheme shell script improved; added code to support the
	stupid AIX linker
     o  Fixed numerous things that caused lint or "gcc -ansi" to complain
     o  Changed the dynamic loading, "dump", and a.out symbol table reading
	code in numerous places to make it work on new systems and to make
	it more readable and maintainable

   Extensions:

     o  Combined lib/util/symbol.o and lib/util/objects.o into new library
	libutil.a; put this library into the default "load-libraries"
     o  Moved lib/util/string.c and lib/util/string.h into the interpreter
     o  Moved files from lib directory into new subdirectory "misc"
     o  Added POSIX sysconf stuff to unix.c to determine max. number of
        open files per process

   Elk/X:

     o  Made the code "lint clean" and "gcc -ansi clean"
     o  Fixed bogus variable definitions in xlib.h and xt.h
     o  Xlib: added support for client-message event
     o  Xt: added code to avoid a bug in Motif 1.1.4
     o  Xt: added optional "mask" argument to context-add-input
     o  Removed site-dependent information from scm/xwidgets (file is
	now created from scm/xwidgets.src during the build process)
     o  Renamed widget .d files that were longer than 14 characters;
	added ALIASES file for each widget set containing mappings from
	real widget names to short names

   Documentation:

     o  Added sub-directory "paper" containing a draft version of a
	paper about Elk

   User-contributed extensions:

     o  A foreign function interface, an Elk Shell, and a vector extension
	have been contributed by J. P. Lewis (contrib/zelk).


Changes from release 1.4 to release 1.5

   General:
     o  Added a "contrib" directory for user-contributed extensions
	that I have not fully tested and/or integrated into Elk
     o  Renamed ORIGIN to COPYRIGHT

   Interpreter kernel:
     o  Added support for the Amiga, A/UX and System V Release 4
	(ELF a.out format)
     o  Added special load-library for MIPS (-lc_G0)
     o  Extension-interface: replaced Val() by Var_Set()/Var_Get()
     o  Modified load, autoload, and require so that multiple .o-files
	can be loaded simultaneously
     o  Added -1+ as a synonym for 1-
     o  Bug fixes:
          o  fixed a GC-related bug
          o  fixed a bug that occurred when allocating a very large heap
	  o  fixed a bug in case-insensitive string comparison
	  o  fixed a bug in macro "when"
	  o  changed and clarified semantics of print-depth/print-length
     o  IEEE 1178/R^4RS compatibility:
          o  replaced close-port by close-input-port and close-output-port
          o  added primitives caaaar .. cddddr
          o  added peek-char primitive
          o  added -i option for case-insensitive operation
     o  Removed -bc option
     o  Removed CBREAK-hack in read-char

   Elk/X:
     o  Fixed several GC-related bugs (objects belonging to Xlib/Xt are
	no longer terminated by garbage collector when unreferenced)
     o  Fixed a bug in the interface to the Grip widget
     o  Modified code to load widgets to make use of new capability to
	load multiple .o-files

   Documentation:
     o  Interpreter kernel:  documented new functions, clarified
	some sections
     o  Xlib/Xt:  documented X-related behaviour of garbage collector,
	pointed out GC-related pitfalls


Changes from release 1.3 to release 1.4

   Interpreter kernel:
     o  Support for the NeXT machines added
     o  New primitive list? provided
     o  Two bugs in the tail recursion code fixed
     o  -v option to trace /bin/ld-calls
     o  man-page written

   Elk/X:
     o  Tested under X11R5
     o  X11R3 and earlier versions are no longer supported
     o  The HP-widget code has been removed from the distribution

     o  New Xlib-primitives:  install-colormap  uninstall-colormap
	list-installed-colormaps  xlib-release-5-or-later?

     o  Xt interface now supports actions and accelerator tables
     o  Bug in set-context-fallback-resources! fixed
     o  New Xt-functions:  widget-name  widget-translate-coordinates
        application-initialize  context-add-action  install-accelerators
        install-all-accelerators  xt-release-5-or-later?

     o  Support for new widget classes: menubutton panner porthole repeater
        simplemenu sme smebsb smeline stripchart tree
     o  vpaned renamed to paned

     o  Example programs have been moved into a new examples directory
	with sub-directories for Scheme, Xlib, Xaw, Motif

     o  New Xaw example programs that demonstrate the new widget classes,
	accelerators, actions, etc.

   Other extensions:
     o  Interface to the GNU gdbm-library
