diff --git a/buffer.py b/buffer.py
index 988dfdc..3607741 100644
--- a/buffer.py
+++ b/buffer.py
@@ -568,7 +568,7 @@ class Binary32Buffer(FileBuffer):
         groupsize = (((2 + self.bytepad) * self.groupsize) + self.grouppad)
         maxsize = groupsize * self.numgroups - self.grouppad
         if ix < maxsize:
-            return (ix // self.groupsize) * self.grouppad + ix * (2 + self.bytepad)
+            return (ix // self.groupsize) * (self.grouppad - 1) + ix * (2 + self.bytepad)
         else:
             return None
     def datax_to_cursory(self, ix):
diff --git a/mode/hex.py b/mode/hex.py
index 6842345..cf698eb 100644
--- a/mode/hex.py
+++ b/mode/hex.py
@@ -99,11 +99,53 @@ class HexOverwriteChar(Method):
         self.args = []
         self.help = "Overwrite %r into the current hex buffer." % c
         self.char = c
+        self.part1, self.part2 = '%02x' % ord(self.char)
     def _execute(self, w, **vargs):
-        w.overwrite_char_at_cursor(self.char)
+        if w.mode.symbolic_edit:
+            b  = w.buffer
+            hb = w.application.methods['hex-backward']
+            (cx, cy) = w.cursor.xy()
+            ix = b.cursorx_to_datax(cy, cx)
+            cx2 = w.buffer.datax_to_cursorx(ix)
+            w.goto(Point(cx2, cy))
+            w.overwrite_char_at_cursor(self.part1)
+            w.overwrite_char_at_cursor(self.part2)
+        elif self.char not in string.hexdigits:
+            return
+        else:
+            w.overwrite_char_at_cursor(self.char)
         end = w.buffer.get_buffer_end()
         while w.cursor_char().isspace() and w.cursor < end:
             w.forward()
+class HexOverwriteSpace(HexOverwriteChar):
+    def __init__(self):
+        self.name = 'hex-overwrite-space'
+        self.args = []
+        self.help = "Overwrite SPACE into the current hex buffer."
+        self.char = ' '
+        self.part1, self.part2 = '%02x' % ord(self.char)
+class HexOverwriteTab(HexOverwriteChar):
+    def __init__(self):
+        self.name = 'hex-overwrite-tab'
+        self.args = []
+        self.help = "Overwrite TAB into the current hex buffer."
+        self.char = '\t'
+        self.part1, self.part2 = '%02x' % ord(self.char)
+class HexOverwriteNewline(HexOverwriteChar):
+    def __init__(self):
+        self.name = 'hex-overwrite-newline'
+        self.args = []
+        self.help = "Overwrite NEWLINE into the current hex buffer."
+        self.char = '\n'
+        self.part1, self.part2 = '%02x' % ord(self.char)
+
+class HexToggleSymbolic(Method):
+    def _execute(self, w, **vargs):
+        w.mode.symbolic_edit = not w.mode.symbolic_edit
+        if w.mode.symbolic_edit:
+            w.set_error("Symbolic editing enabled")
+        else:
+            w.set_error("Symbolic editing disabled")
 
 class ShowX86Instruction(Method):
     ''''''
@@ -170,7 +212,8 @@ class Hex(mode.Fundamental):
     ctrans = ''.join(_ctrans)
     actions = [HexForward, HexBackward, HexForwardWord, HexBackwardWord,
                HexStartOfLine, HexEndOfLine, ShowAddress, ShowX86Instruction,
-               GotoAddress, HexSetByteOrder]
+               GotoAddress, HexSetByteOrder, HexToggleSymbolic,
+               HexOverwriteSpace, HexOverwriteTab, HexOverwriteNewline]
     def __init__(self, w):
         mode.Fundamental.__init__(self, w)
         self.bindings = {}
@@ -257,8 +300,12 @@ class Hex(mode.Fundamental):
 
         # create all the insert actions for the basic text input
         for c in string.letters + string.digits + string.punctuation:
-            if c in string.hexdigits:
-                self.add_action_and_bindings(HexOverwriteChar(c), (c,))
+            self.add_action_and_bindings(HexOverwriteChar(c), (c,))
+        self.add_bindings('hex-overwrite-space', ('SPACE',))
+        self.add_bindings('hex-overwrite-tab', ('TAB',))
+        self.add_bindings('hex-overwrite-newline', ('RETURN',))
+
+        self.symbolic_edit = False
 
     def get_address(self, y, x):
         return (y * 16) + x