diff --git a/Makefile.am b/Makefile.am
index 48cb8b296..b647fb589 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,7 +1,7 @@
 SUBDIRS = Include Lib Simulator Tools Tests
 
-EXTRA_DIST = Makefile.extra README.Win32 README.autoconf README.running \
-	Thanks acsite.m4
+EXTRA_DIST = Makefile.extra README.Unix README.Win32 README.autoconf \
+	README.running Thanks acsite.m4
 
 dist-hook:
 	tar cf - Hints | (cd $(distdir); tar xvf -)
diff --git a/NEWS b/NEWS
index 24279a101..a0fe32446 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,10 @@
 New in 0.52
 * Fog color tries to track the sky color at the center of view in sunrise
   and sunset situations.
+* Optimizations from Norman Vine
+* Code fixes and tweaks from Charlie Hotchkiss.
+* Added an --enable/disable-sound option.
+* Added a pause key "p"
 
 New in 0.51
 * Translucent menus
diff --git a/README b/README
index 80d26a9ae..d35321dba 100644
--- a/README
+++ b/README
@@ -24,6 +24,8 @@ Please see .... for more information on ....
 
 - README:  This file
 
+- README.Unix:  Hints and tips for compiling on Unix
+
 - README.Win32:  Specific Win32 compiling information and instructions
 
 - README.autoconf:  Info on updating the make system (adding new source
diff --git a/README.Unix b/README.Unix
new file mode 100644
index 000000000..69747558e
--- /dev/null
+++ b/README.Unix
@@ -0,0 +1,22 @@
+*** not much here yet ***
+
+If you are reading this in hopes that you will find the answer to a
+specific question, please send the question to curt@me.umn.edu and
+suggest that I include the answer here.
+
+
+GLUT
+====
+
+Flight Gear requires GLUT.  GLUT needs to be installed on your system
+before you can build Flight Gear.  GLUT can be found at:
+
+    http://reality.sgi.com/opengl/glut3/glut3.html
+
+GLUT (pronounced like the glut in gluttony) is the OpenGL Utility
+Toolkit, a window system independent toolkit for writing OpenGL
+programs. It implements a simple windowing application programming
+interface (API) for OpenGL. GLUT makes it considerably easier to learn
+about and explore OpenGL programming.  GLUT provides a portable API so
+you can write a single OpenGL program that works on both Win32 PCs and
+X11 workstations.
diff --git a/README.autoconf b/README.autoconf
index b937e5cf5..d13a2badb 100644
--- a/README.autoconf
+++ b/README.autoconf
@@ -11,12 +11,14 @@ install the following packages:
 
     - GNU autoconf 2.12 (available from ftp://prep.ai.mit.edu/pub/gnu)
     - GNU automake 1.2h (available from ftp://ftp.cygnus.com/pub/tromey)
+
+Libtool is not currently used:
+
     - GNU libtool 1.2   (available from ftp://prep.ai.mit.edu/pub/gnu)
                         (or maybe ftp://alpha.gnu.org/gnu)
+    - After upgrading libtool, if we were using it, you would want to run:
 
-After upgrading libtool, you will want to run:
-
-    libtoolize --force
+      libtoolize --force
 
 When making a change to any of these files you will need to run:
 
@@ -28,5 +30,5 @@ Then follow the regular build procedure:
 
 For debuging purposes you might want to try something like:
 
-    CFLAGS=-Wall CXXFLAGS=-Wall ./configure --disable-shared; make; make install
+    CFLAGS=-Wall CXXFLAGS=-Wall ./configure; make; make install
 
diff --git a/aclocal.m4 b/aclocal.m4
index dc8a13b49..f57d6ff83 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -111,244 +111,6 @@ else
 fi
 AC_SUBST($1)])
 
-
-# serial 24 AM_PROG_LIBTOOL
-AC_DEFUN(AM_PROG_LIBTOOL,
-[AC_REQUIRE([AM_ENABLE_SHARED])dnl
-AC_REQUIRE([AM_ENABLE_STATIC])dnl
-AC_REQUIRE([AC_CANONICAL_HOST])dnl
-AC_REQUIRE([AC_PROG_RANLIB])dnl
-AC_REQUIRE([AC_PROG_CC])dnl
-AC_REQUIRE([AM_PROG_LD])dnl
-AC_REQUIRE([AM_PROG_NM])dnl
-AC_REQUIRE([AC_PROG_LN_S])dnl
-dnl
-# Always use our own libtool.
-LIBTOOL='$(SHELL) $(top_builddir)/libtool'
-AC_SUBST(LIBTOOL)dnl
-
-# Check for any special flags to pass to ltconfig.
-libtool_flags=
-test "$enable_shared" = no && libtool_flags="$libtool_flags --disable-shared"
-test "$enable_static" = no && libtool_flags="$libtool_flags --disable-static"
-test "$silent" = yes && libtool_flags="$libtool_flags --silent"
-test "$ac_cv_prog_gcc" = yes && libtool_flags="$libtool_flags --with-gcc"
-test "$ac_cv_prog_gnu_ld" = yes && libtool_flags="$libtool_flags --with-gnu-ld"
-
-# Some flags need to be propagated to the compiler or linker for good
-# libtool support.
-case "$host" in
-*-*-irix6*)
-  # Find out which ABI we are using.
-  echo '[#]line __oline__ "configure"' > conftest.$ac_ext
-  if AC_TRY_EVAL(ac_compile); then
-    case "`/usr/bin/file conftest.o`" in
-    *32-bit*)
-      LD="${LD-ld} -32"
-      ;;
-    *N32*)
-      LD="${LD-ld} -n32"
-      ;;
-    *64-bit*)
-      LD="${LD-ld} -64"
-      ;;
-    esac
-  fi
-  rm -rf conftest*
-  ;;
-
-*-*-sco3.2v5*)
-  # On SCO OpenServer 5, we need -belf to get full-featured binaries.
-  CFLAGS="$CFLAGS -belf"
-  ;;
-esac
-
-# Actually configure libtool.  ac_aux_dir is where install-sh is found.
-CC="$CC" CFLAGS="$CFLAGS" CPPFLAGS="$CPPFLAGS" \
-LD="$LD" NM="$NM" RANLIB="$RANLIB" LN_S="$LN_S" \
-${CONFIG_SHELL-/bin/sh} $ac_aux_dir/ltconfig \
-$libtool_flags --no-verify $ac_aux_dir/ltmain.sh $host \
-|| AC_MSG_ERROR([libtool configure failed])
-])
-
-# AM_ENABLE_SHARED - implement the --enable-shared flag
-# Usage: AM_ENABLE_SHARED[(DEFAULT)]
-#   Where DEFAULT is either `yes' or `no'.  If omitted, it defaults to
-#   `yes'.
-AC_DEFUN(AM_ENABLE_SHARED,
-[define([AM_ENABLE_SHARED_DEFAULT], ifelse($1, no, no, yes))dnl
-AC_ARG_ENABLE(shared,
-changequote(<<, >>)dnl
-<<  --enable-shared         build shared libraries [default=>>AM_ENABLE_SHARED_DEFAULT]
-changequote([, ])dnl
-[  --enable-shared=PKGS    only build shared libraries if the current package
-                          appears as an element in the PKGS list],
-[p=${PACKAGE-default}
-case "$enableval" in
-yes) enable_shared=yes ;;
-no) enable_shared=no ;;
-*)
-  enable_shared=no
-  # Look at the argument we got.  We use all the common list separators.
-  IFS="${IFS= 	}"; ac_save_ifs="$IFS"; IFS="${IFS}:,"
-  for pkg in $enableval; do
-    if test "X$pkg" = "X$p"; then
-      enable_shared=yes
-    fi
-  done
-  IFS="$ac_save_ifs"
-  ;;
-esac],
-enable_shared=AM_ENABLE_SHARED_DEFAULT)dnl
-])
-
-# AM_DISABLE_SHARED - set the default shared flag to --disable-shared
-AC_DEFUN(AM_DISABLE_SHARED,
-[AM_ENABLE_SHARED(no)])
-
-# AM_DISABLE_STATIC - set the default static flag to --disable-static
-AC_DEFUN(AM_DISABLE_STATIC,
-[AM_ENABLE_STATIC(no)])
-
-# AM_ENABLE_STATIC - implement the --enable-static flag
-# Usage: AM_ENABLE_STATIC[(DEFAULT)]
-#   Where DEFAULT is either `yes' or `no'.  If omitted, it defaults to
-#   `yes'.
-AC_DEFUN(AM_ENABLE_STATIC,
-[define([AM_ENABLE_STATIC_DEFAULT], ifelse($1, no, no, yes))dnl
-AC_ARG_ENABLE(static,
-changequote(<<, >>)dnl
-<<  --enable-static         build static libraries [default=>>AM_ENABLE_STATIC_DEFAULT]
-changequote([, ])dnl
-[  --enable-static=PKGS    only build shared libraries if the current package
-                          appears as an element in the PKGS list],
-[p=${PACKAGE-default}
-case "$enableval" in
-yes) enable_static=yes ;;
-no) enable_static=no ;;
-*)
-  enable_static=no
-  # Look at the argument we got.  We use all the common list separators.
-  IFS="${IFS= 	}"; ac_save_ifs="$IFS"; IFS="${IFS}:,"
-  for pkg in $enableval; do
-    if test "X$pkg" = "X$p"; then
-      enable_static=yes
-    fi
-  done
-  IFS="$ac_save_ifs"
-  ;;
-esac],
-enable_static=AM_ENABLE_STATIC_DEFAULT)dnl
-])
-
-
-# AM_PROG_LD - find the path to the GNU or non-GNU linker
-AC_DEFUN(AM_PROG_LD,
-[AC_ARG_WITH(gnu-ld,
-[  --with-gnu-ld           assume the C compiler uses GNU ld [default=no]],
-test "$withval" = no || with_gnu_ld=yes, with_gnu_ld=no)
-AC_REQUIRE([AC_PROG_CC])
-ac_prog=ld
-if test "$ac_cv_prog_gcc" = yes; then
-  # Check if gcc -print-prog-name=ld gives a path.
-  AC_MSG_CHECKING([for ld used by GCC])
-  ac_prog=`($CC -print-prog-name=ld) 2>&5`
-  case "$ac_prog" in
-  # Accept absolute paths.
-  /* | [A-Za-z]:\\*)
-    test -z "$LD" && LD="$ac_prog"
-    ;;
-  "")
-    # If it fails, then pretend we aren't using GCC.
-    ac_prog=ld
-    ;;
-  *)
-    # If it is relative, then search for the first ld in PATH.
-    with_gnu_ld=unknown
-    ;;
-  esac
-elif test "$with_gnu_ld" = yes; then
-  AC_MSG_CHECKING([for GNU ld])
-else
-  AC_MSG_CHECKING([for non-GNU ld])
-fi
-AC_CACHE_VAL(ac_cv_path_LD,
-[if test -z "$LD"; then
-  IFS="${IFS= 	}"; ac_save_ifs="$IFS"; IFS="${IFS}:"
-  for ac_dir in $PATH; do
-    test -z "$ac_dir" && ac_dir=.
-    if test -f "$ac_dir/$ac_prog"; then
-      ac_cv_path_LD="$ac_dir/$ac_prog"
-      # Check to see if the program is GNU ld.  I'd rather use --version,
-      # but apparently some GNU ld's only accept -v.
-      # Break only if it was the GNU/non-GNU ld that we prefer.
-      if "$ac_cv_path_LD" -v 2>&1 < /dev/null | egrep '(GNU|with BFD)' > /dev/null; then
-	test "$with_gnu_ld" != no && break
-      else
-        test "$with_gnu_ld" != yes && break
-      fi
-    fi
-  done
-  IFS="$ac_save_ifs"
-else
-  ac_cv_path_LD="$LD" # Let the user override the test with a path.
-fi])
-LD="$ac_cv_path_LD"
-if test -n "$LD"; then
-  AC_MSG_RESULT($LD)
-else
-  AC_MSG_RESULT(no)
-fi
-test -z "$LD" && AC_MSG_ERROR([no acceptable ld found in \$PATH])
-AC_SUBST(LD)
-AM_PROG_LD_GNU
-])
-
-AC_DEFUN(AM_PROG_LD_GNU,
-[AC_CACHE_CHECK([if the linker ($LD) is GNU ld], ac_cv_prog_gnu_ld,
-[# I'd rather use --version here, but apparently some GNU ld's only accept -v.
-if $LD -v 2>&1 </dev/null | egrep '(GNU|with BFD)' 1>&5; then
-  ac_cv_prog_gnu_ld=yes
-else
-  ac_cv_prog_gnu_ld=no
-fi])
-])
-
-# AM_PROG_NM - find the path to a BSD-compatible name lister
-AC_DEFUN(AM_PROG_NM,
-[AC_MSG_CHECKING([for BSD-compatible nm])
-AC_CACHE_VAL(ac_cv_path_NM,
-[case "$NM" in
-/* | [A-Za-z]:\\*)
-  ac_cv_path_NM="$NM" # Let the user override the test with a path.
-  ;;
-*)
-  IFS="${IFS= 	}"; ac_save_ifs="$IFS"; IFS="${IFS}:"
-  for ac_dir in /usr/ucb /usr/ccs/bin $PATH /bin; do
-    test -z "$ac_dir" && ac_dir=.
-    if test -f $ac_dir/nm; then
-      # Check to see if the nm accepts a BSD-compat flag.
-      # Adding the `sed 1q' prevents false positives on HP-UX, which says:
-      #   nm: unknown option "B" ignored
-      if ($ac_dir/nm -B /dev/null 2>&1 | sed '1q'; exit 0) | egrep /dev/null >/dev/null; then
-        ac_cv_path_NM="$ac_dir/nm -B"
-      elif ($ac_dir/nm -p /dev/null 2>&1 | sed '1q'; exit 0) | egrep /dev/null >/dev/null; then
-        ac_cv_path_NM="$ac_dir/nm -p"
-      else
-        ac_cv_path_NM="$ac_dir/nm"
-      fi
-      break
-    fi
-  done
-  IFS="$ac_save_ifs"
-  test -z "$ac_cv_path_NM" && ac_cv_path_NM=nm
-  ;;
-esac])
-NM="$ac_cv_path_NM"
-AC_MSG_RESULT([$NM])
-AC_SUBST(NM)
-])
-
 # Define a conditional.
 
 AC_DEFUN(AM_CONDITIONAL,
diff --git a/configure.in b/configure.in
index b084d5f0a..da5a73a60 100644
--- a/configure.in
+++ b/configure.in
@@ -2,26 +2,32 @@ dnl Process this file with autoconf to produce a configure script.
 dnl
 dnl The basis for this file was generated by autoscan(1) [pere 1998-03-19]
 dnl
+
 AC_INIT(Simulator/Aircraft/aircraft.c)
 
+dnl Let the Win32 user specify if they want to build with the SGI
+dnl opengl.dll as opposed to the more standard openg32.dll
+AC_ARG_WITH(sgiopengl, [  --with-sgiopengl        Build against opengl.dll glu.dll and glut.dll])
+
 dnl Initialize the automake stuff
 AM_INIT_AUTOMAKE(FlightGear, 0.52)
 
 dnl Checks for programs.
-
 AC_PROG_MAKE_SET
 AC_PROG_CC
 AC_PROG_CXX
+AC_PROG_RANLIB
 AC_PROG_INSTALL
 AC_PROG_LN_S
-dnl Initialize libtool
-AM_PROG_LIBTOOL
 
-dnl Initialize maintainer mode (I'm not sure what this does)
+dnl Initialize libtool
+dnl AM_PROG_LIBTOOL
+
+dnl Initialize maintainer mode
 dnl AM_MAINTAINER_MODE
 
 dnl This is needed for AC_TRY_COMPILE later
-AC_ISC_POSIX
+dnl AC_ISC_POSIX
 
 dnl Check to see if this `configure' is being run in the `Cygwin32' environment
 dnl AM_CYGWIN32
@@ -48,8 +54,11 @@ AM_CONDITIONAL(ENABLE_AUDIO_SUPPORT, \
 	test -r /usr/include/soundcard.h \
 		-o -r /usr/include/linux/soundcard.h \
 		-o -r /usr/include/machine/soundcard.h \
+		-o -r /usr/include/audio.h \
 		-o "x$ac_cv_header_windows_h" = "xyes" )
 
+AM_CONDITIONAL(ENABLE_IRIX_AUDIO, test -r /usr/include/audio.h)
+
 AM_CONDITIONAL(ENABLE_WIN32_AUDIO, test "x$ac_cv_header_windows_h" = "xyes")
 
 dnl extra library and include directories
@@ -77,68 +86,87 @@ AC_CHECK_LIB(SM, SmcOpenConnection)
 AC_CHECK_LIB(Xt, XtMalloc)
 AC_CHECK_LIB(Xmu, XmuLookupStandardColormap)
 
-# dnl Solaris OpenGL pain
-# AC_CHECK_LIB(eprintf, __eprintf)
+dnl check for OpenGL related libraries
 
-AC_CHECK_LIB(GLcore, glNewList)
-if test "x$ac_cv_lib_GLcore_glNewList" = "xno" ; then
-    dnl if no GLcore, check for GL
-    AC_CHECK_LIB(GL, glNewList)
-    if test "x$ac_cv_lib_GL_glNewList" = "xno" ; then
-        dnl if no GL, check for MesaGL
-        AC_CHECK_LIB(MesaGL, glNewList)
+if test "x$ac_cv_header_windows_h" != "xyes" ; then
+    dnl Reasonable stuff non-windoze variants ... :-)
+
+    AC_CHECK_LIB(GLcore, glNewList)
+    if test "x$ac_cv_lib_GLcore_glNewList" = "xno" ; then
+	dnl if no GLcore, check for GL
+	AC_CHECK_LIB(GL, glNewList)
+	if test "x$ac_cv_lib_GL_glNewList" = "xno" ; then
+	    dnl if no GL, check for MesaGL
+	    AC_CHECK_LIB(MesaGL, glNewList)
+	fi
+    else
+	dnl if GLcore found, then also check for GL
+	AC_CHECK_LIB(GL, glXCreateContext)
     fi
+
+    dnl if using mesa, check for xmesa.h
+    if test "x$ac_cv_lib_MesaGL_glNewList" = "xyes" ; then
+	AC_CHECK_HEADER(GL/xmesa.h)
+	AM_CONDITIONAL(ENABLE_XMESA_FX, \
+		       test "x$ac_cv_header_GL_xmesa_h" = "xyes")
+    else
+        dnl force a failed check
+        AM_CONDITIONAL(ENABLE_XMESA_FX, test "no" = "yes")
+    fi
+
+    AC_CHECK_LIB(GLU, gluLookAt)
+    if test "x$ac_cv_lib_GLU_gluLookAt" = "xno" ; then
+	dnl if no GLU, check for MesaGLU
+	AC_CHECK_LIB(MesaGLU, gluLookAt)
+    fi
+
+    AC_CHECK_LIB(glut, glutGetModifiers)
 else
-    dnl if GLcore found, then also check for GL
-    AC_CHECK_LIB(GL, glXCreateContext)
-fi
+    dnl Win32 is a little wierd because it has to try to handle the various
+    dnl winbloze-isms.  We'll just do this manually for now.
 
-dnl if using mesa, check for xmesa.h
-if test "x$ac_cv_lib_MesaGL_glNewList" = "xyes" ; then
-    AC_CHECK_HEADER(GL/xmesa.h)
-    AM_CONDITIONAL(ENABLE_XMESA_FX, test "x$ac_cv_header_GL_xmesa_h" = "xyes")
-else
-    dnl force a failed check
-    AM_CONDITIONAL(ENABLE_XMESA_FX, test "no" = "yes")
-fi
-
-AC_CHECK_LIB(GLU, gluLookAt)
-if test "x$ac_cv_lib_GLU_gluLookAt" = "xno" ; then
-    dnl if no GLU, check for MesaGLU
-    AC_CHECK_LIB(MesaGLU, gluLookAt)
-fi
-
-AC_CHECK_LIB(glut, glutGetModifiers)
-	
-dnl Win32 is a little wierd because it has to try to handle the various
-dnl winbloze-isms.  We'll just do this manually for now.
-if test "x$ac_cv_header_windows_h" = "xyes" ; then
     echo Win32 specific hacks...
     AC_DEFINE(WIN32)
 
-    dnl Note, the double square brackets are required becuase single brackets
-    dnl seem to get stripped out
-    if [[ -f `pwd`/Win32/glut.dll ]]; then
-        echo "    found glut.dll, adding -lglut"
-        LIBS="$LIBS -lglut"
-    else
-        echo "    Cannot find glut.dll"
-        exit 1
+    dnl force a failed check since we will be building under windoze
+    AM_CONDITIONAL(ENABLE_XMESA_FX, test "no" = "yes")
+
+    if test "x$with_sgiopengl" = "xyes" ; then
+        echo "Building with glut.dll, glu.dll, and opengl.dll"
+	WIN32_GLUT=glut
+	WIN32_GLU=glu
+	WIN32_OPENGL=opengl
+    else 
+	echo "Building with glut32.dll, glu32.dll, and opengl32.dll"
+	WIN32_GLUT=glut32
+	WIN32_GLU=glu32
+	WIN32_OPENGL=opengl32
     fi
-    if [[ -f `pwd`/Win32/glu.dll ]]; then
-        echo "    found glu.dll"
+
+    if test -f `pwd`/Win32/${WIN32_GLUT}.dll; then
+	echo "    found ${WIN32_GLUT}.dll, adding -l${WIN32_GLUT}"
+	LIBS="$LIBS -l${WIN32_GLUT}"
     else
-        echo "    Can't find glu.dll, assuming it's someplace"
+	echo "    Cannot find ${WIN32_GLUT}.dll"
+	exit 1
     fi
-    echo "    adding -lglu"
-    LIBS="$LIBS -lglu"
-    if [[ -f `pwd`/Win32/opengl.dll ]]; then
-        echo "    found opengl.dll"
+
+    if test -f `pwd`/Win32/${WIN32_GLU}.dll; then
+	echo "    found ${WIN32_GLU}.dll"
     else
-        echo "    Can't find opengl.dll, assuming it's somplace"
+	echo "    Can't find ${WIN32_GLU}.dll, assuming it's someplace"
     fi
-    echo "    adding -lopengl"
-    LIBS="$LIBS -lopengl"
+    echo "    adding -l${WIN32_GLU}"
+    LIBS="$LIBS -l${WIN32_GLU}"
+
+    if test -f `pwd`/Win32/${WIN32_OPENGL}.dll; then
+	echo "    found ${WIN32_OPENGL}.dll"
+    else
+	echo "    Can't find ${WIN32_OPENGL}.dll, assuming it's somplace"
+    fi
+    echo "    adding -l${WIN32_OPENGL}"
+    LIBS="$LIBS -l${WIN32_OPENGL}"
+
     echo "    adding -luser32 -lgdi32"
     LIBS="$LIBS -luser32 -lgdi32"
     ac_cv_lib_glut_glutGetModifiers="yes"