diff --git a/cgdb/cgdbrc.c b/cgdb/cgdbrc.c
index 8a01b5b0..6f0722a2 100644
--- a/cgdb/cgdbrc.c
+++ b/cgdb/cgdbrc.c
@@ -47,6 +47,7 @@ enum ConfigType {
 static int command_set_arrowstyle(const char *value);
 static int command_set_cgdb_mode_key(const char *value);
 static int command_set_winsplit(const char *value);
+static int command_set_splitorientation(const char *value);
 static int command_set_timeout(int value);
 static int command_set_timeoutlen(int value);
 static int command_set_ttimeout(int value);
@@ -74,6 +75,7 @@ static struct cgdbrc_config_option cgdbrc_config_options[CGDBRC_WRAPSCAN + 1] =
     {CGDBRC_TTIMEOUT_LEN, {100}},
     {CGDBRC_WINMINHEIGHT, {0}},
     {CGDBRC_WINSPLIT, {WIN_SPLIT_EVEN}},
+    {CGDBRC_SPLITORIENTATION, {SPLIT_HORIZONTAL}},
     {CGDBRC_WRAPSCAN, {1}}
 };
 
@@ -136,6 +138,10 @@ static struct ConfigVariable {
             /* winsplit */
     {
     "winsplit", "winsplit", CONFIG_TYPE_FUNC_STRING, command_set_winsplit},
+            /* splitorientation */
+    {
+    "splitorientation", "so", CONFIG_TYPE_FUNC_STRING,
+                command_set_splitorientation},
             /* wrapscan */
     {
 "wrapscan", "ws", CONFIG_TYPE_BOOL,
@@ -334,6 +340,26 @@ int command_set_winsplit(const char *value)
     return 0;
 }
 
+int command_set_splitorientation(const char *value)
+{
+    struct cgdbrc_config_option option;
+    SPLIT_ORIENTATION_TYPE orientation = SPLIT_HORIZONTAL;
+
+    option.option_kind = CGDBRC_SPLITORIENTATION;
+
+    if (strcasecmp(value, "horizontal") == 0)
+        orientation = SPLIT_HORIZONTAL;
+    else if (strcasecmp(value, "vertical") == 0)
+        orientation = SPLIT_VERTICAL;
+
+    option.variant.win_orientation_val = orientation;
+    if (cgdbrc_set_val(option))
+        return 1;
+    if_set_splitorientation(orientation);
+
+    return 0;
+}
+
 static int command_set_winminheight(int value)
 {
     struct cgdbrc_config_option option;
diff --git a/cgdb/cgdbrc.h b/cgdb/cgdbrc.h
index bac90bba..6c98743e 100644
--- a/cgdb/cgdbrc.h
+++ b/cgdb/cgdbrc.h
@@ -99,6 +99,16 @@ typedef enum { WIN_SPLIT_FREE = -3, /* split point not on quarter mark */
     WIN_SPLIT_TOP_FULL = 2      /* src window is 100% of screen */
 } WIN_SPLIT_TYPE;
 
+/** window split orientation type enumeration
+ *  
+ *  SPLIT_VERTICAL and SPLIT_HORIZONTAL refer to the orientation
+ *  of the split between the source and GDB windows.
+ */
+typedef enum {
+    SPLIT_HORIZONTAL = 0,       /* source above and GDB below (default) */
+    SPLIT_VERTICAL = 1          /* source left and GDB right            */
+} SPLIT_ORIENTATION_TYPE;
+
 /** All of the different configuration options */
 enum cgdbrc_option_kind {
     CGDBRC_ARROWSTYLE,
@@ -114,6 +124,7 @@ enum cgdbrc_option_kind {
     CGDBRC_TTIMEOUT_LEN,
     CGDBRC_WINMINHEIGHT,
     CGDBRC_WINSPLIT,
+    CGDBRC_SPLITORIENTATION,
     CGDBRC_WRAPSCAN
 };
 
@@ -139,6 +150,8 @@ struct cgdbrc_config_option {
         enum tokenizer_language_support language_support_val;
         /* option_kind == CGDBRC_WINSPLIT */
         WIN_SPLIT_TYPE win_split_val;
+        /* option_kind == CGDBRC_WINORIENTATION */
+        SPLIT_ORIENTATION_TYPE win_orientation_val;
     } variant;
 };
 
diff --git a/cgdb/interface.c b/cgdb/interface.c
index d0f37acc..0838a87a 100644
--- a/cgdb/interface.c
+++ b/cgdb/interface.c
@@ -82,7 +82,7 @@ extern struct tgdb *tgdb;
 static int interface_winminheight = 0;
 
 /* The offset that determines allows gdb/sources window to grow or shrink */
-static int window_height_shift;
+static int window_shift;
 
 /* This is for the tty I/O window */
 #define TTY_WIN_DEFAULT_HEIGHT ((interface_winminheight>4)?interface_winminheight:4)
@@ -96,6 +96,7 @@ static int tty_win_height_shift = 0;
 
 /* Current window split state */
 WIN_SPLIT_TYPE cur_win_split = WIN_SPLIT_EVEN;
+SPLIT_ORIENTATION_TYPE cur_split_orientation = SPLIT_HORIZONTAL;
 
 /* --------------- */
 /* Local Variables */
@@ -187,13 +188,19 @@ static int get_src_col(void)
     return 0;
 }
 
+static int get_src_status_height(void);
+
 static int get_src_height(void)
 {
-    return ((int) (((screen_size.ws_row + 0.5) / 2) + window_height_shift));
+    if (cur_split_orientation == SPLIT_HORIZONTAL)
+        return ((int) (((screen_size.ws_row + 0.5) / 2) + window_shift));
+    return (screen_size.ws_row) - get_src_status_height();
 }
 
 static int get_src_width(void)
 {
+    if (cur_split_orientation == SPLIT_VERTICAL)
+        return ((int) (((screen_size.ws_col + 0.5) / 2) + window_shift));
     return (screen_size.ws_col);
 }
 
@@ -207,7 +214,7 @@ static int get_src_status_row(void)
 
 static int get_src_status_col(void)
 {
-    return 0;
+    return get_src_col();;
 }
 
 static int get_src_status_height(void)
@@ -217,17 +224,42 @@ static int get_src_status_height(void)
 
 static int get_src_status_width(void)
 {
-    return (screen_size.ws_col);
+    return get_src_width();
+}
+
+/* These are for the separator line in horizontal split mode */
+static int get_sep_row(void)
+{
+    return 0;
+}
+
+static int get_sep_col(void)
+{
+    return get_src_col() + get_src_width();
+}
+
+static int get_sep_height(void)
+{
+    return (screen_size.ws_row);
+}
+
+static int get_sep_width(void)
+{
+    return 1;
 }
 
 /* This is for the tty I/O window */
 static int get_tty_row(void)
 {
-    return get_src_status_row() + get_src_status_height();
+    if (cur_split_orientation == SPLIT_HORIZONTAL)
+        return get_src_status_row() + get_src_status_height();
+    return 0;
 }
 
 static int get_tty_col(void)
 {
+    if (cur_split_orientation == SPLIT_VERTICAL)
+        return get_sep_col() + get_sep_width();
     return 0;
 }
 
@@ -236,8 +268,12 @@ static int get_tty_height(void)
     return TTY_WIN_OFFSET;
 }
 
+static int get_gdb_width(void);
+
 static int get_tty_width(void)
 {
+    if (cur_split_orientation == SPLIT_VERTICAL)
+        return get_gdb_width();
     return (screen_size.ws_col);
 }
 
@@ -249,7 +285,7 @@ static int get_tty_status_row(void)
 
 static int get_tty_status_col(void)
 {
-    return 0;
+    return get_tty_col();
 }
 
 static int get_tty_status_height(void)
@@ -259,7 +295,7 @@ static int get_tty_status_height(void)
 
 static int get_tty_status_width(void)
 {
-    return (screen_size.ws_col);
+    return get_tty_width();
 }
 
 /* This is for the debugger window */
@@ -268,30 +304,59 @@ static int get_gdb_row(void)
     if (tty_win_on)
         return get_tty_status_row() + get_tty_status_height();
 
-    return get_src_status_row() + get_src_status_height();
+    if (cur_split_orientation == SPLIT_HORIZONTAL)
+        return get_src_status_row() + get_src_status_height();
+
+    return 0;
 }
 
 static int get_gdb_col(void)
 {
+    if (cur_split_orientation == SPLIT_VERTICAL)
+        return get_sep_col() + get_sep_width();
     return 0;
 }
 
 int get_gdb_height(void)
 {
-    int window_size = ((screen_size.ws_row / 2) - window_height_shift - 1);
-    int odd_screen_size = (screen_size.ws_row % 2);
+    if (cur_split_orientation == SPLIT_HORIZONTAL) {
+        int window_size = ((screen_size.ws_row / 2) - window_shift - 1);
+        int odd_screen_size = (screen_size.ws_row % 2);
 
-    if (tty_win_on)
-        return window_size - TTY_WIN_OFFSET + odd_screen_size - 1;
+        if (tty_win_on)
+            return window_size - TTY_WIN_OFFSET + odd_screen_size - 1;
 
-    return window_size + odd_screen_size;
+        return window_size + odd_screen_size;
+    }
+
+    return (screen_size.ws_row) - (tty_win_on ? TTY_WIN_OFFSET + 1 : 0);
 }
 
 static int get_gdb_width(void)
 {
+    if (cur_split_orientation == SPLIT_VERTICAL) {
+        int window_size = ((screen_size.ws_col / 2) - window_shift - 1);
+        int odd_screen_size = (screen_size.ws_col % 2);
+
+        return window_size + odd_screen_size;
+    }
+
     return (screen_size.ws_col);
 }
 
+static void separator_display()
+{
+    int col = get_sep_col();
+    int row = get_sep_row();
+    int last_row = row + get_sep_height();
+
+    for (; row < last_row; ++row) {
+        wmove(stdscr, row, col);
+        waddch(stdscr, VERT_LINE);
+        wrefresh(stdscr);
+    }
+}
+
 /* ---------------------------------------
  * Below is the core body of the interface
  * --------------------------------------- */
@@ -431,6 +496,9 @@ void if_draw(void)
     if (get_src_height() > 0)
         source_display(src_win, focus == CGDB);
 
+    if (cur_split_orientation == SPLIT_VERTICAL)
+        separator_display();
+
     if (tty_win_on && get_tty_height() > 0)
         scr_refresh(tty_win, focus == TTY);
 
@@ -454,22 +522,25 @@ void if_draw(void)
  */
 static void validate_window_sizes(void)
 {
-    int tty_window_offset = (tty_win_on) ? TTY_WIN_OFFSET + 1 : 0;
-    int odd_height = (HEIGHT + 1) % 2;
-    int max_window_height_shift = (HEIGHT / 2) - tty_window_offset - odd_height;
-    int min_window_height_shift = -(HEIGHT / 2);
+    int h_or_w = cur_split_orientation == SPLIT_HORIZONTAL ? HEIGHT : WIDTH;
+    int tty_window_offset = (tty_win_on
+            && cur_split_orientation == SPLIT_HORIZONTAL)
+            ? TTY_WIN_OFFSET + 1 : 0;
+    int odd_size = (h_or_w + 1) % 2;
+    int max_window_size_shift = (h_or_w / 2) - tty_window_offset - odd_size;
+    int min_window_size_shift = -(h_or_w / 2);
 
     /* update max and min based off of users winminheight request */
-    min_window_height_shift += interface_winminheight;
-    max_window_height_shift -= interface_winminheight;
+    min_window_size_shift += interface_winminheight;
+    max_window_size_shift -= interface_winminheight;
 
     /* Make sure that the windows offset is within its bounds: 
      * This checks the window offset.
      * */
-    if (window_height_shift > max_window_height_shift)
-        window_height_shift = max_window_height_shift;
-    else if (window_height_shift < min_window_height_shift)
-        window_height_shift = min_window_height_shift;
+    if (window_shift > max_window_size_shift)
+        window_shift = max_window_size_shift;
+    else if (window_shift < min_window_size_shift)
+        window_shift = min_window_size_shift;
 }
 
 /* if_layout: Update the layout of the screen based on current terminal size.
@@ -588,7 +659,7 @@ int if_resize_term(void)
 static void increase_win_height(int jump_or_tty)
 {
     int height = (HEIGHT / 2) - ((tty_win_on) ? TTY_WIN_OFFSET + 1 : 0);
-    int old_window_height_shift = window_height_shift;
+    int old_window_height_shift = window_shift;
     int old_tty_win_height_shift = tty_win_height_shift;
 
     if (jump_or_tty) {
@@ -606,10 +677,10 @@ static void increase_win_height(int jump_or_tty)
             /* no tty window */
             if (cur_win_split == WIN_SPLIT_FREE) {
                 /* cur position is not on mark, find nearest mark */
-                cur_win_split = (int) (2 * window_height_shift) / height;
+                cur_win_split = (int) (2 * window_shift) / height;
 
                 /* handle rounding on either side of mid-way mark */
-                if (window_height_shift > 0) {
+                if (window_shift > 0) {
                     cur_win_split++;
                 }
             } else {
@@ -623,17 +694,17 @@ static void increase_win_height(int jump_or_tty)
             }
 
             /* set window height to specified quarter mark */
-            window_height_shift = (int) (height * (cur_win_split / 2.0));
+            window_shift = (int) (height * (cur_win_split / 2.0));
         }
     } else {
         /* user input: '=' */
         cur_win_split = WIN_SPLIT_FREE; /* cur split is not on a mark */
-        window_height_shift++;  /* increase src window size by 1 */
+        window_shift++;         /* increase src window size by 1 */
 
     }
 
     /* reduce flicker by avoiding unnecessary redraws */
-    if (window_height_shift != old_window_height_shift ||
+    if (window_shift != old_window_height_shift ||
             tty_win_height_shift != old_tty_win_height_shift) {
         if_layout();
     }
@@ -651,7 +722,7 @@ static void increase_win_height(int jump_or_tty)
 static void decrease_win_height(int jump_or_tty)
 {
     int height = HEIGHT / 2;
-    int old_window_height_shift = window_height_shift;
+    int old_window_height_shift = window_shift;
     int old_tty_win_height_shift = tty_win_height_shift;
 
     if (jump_or_tty) {
@@ -667,10 +738,10 @@ static void decrease_win_height(int jump_or_tty)
             /* no tty window */
             if (cur_win_split == WIN_SPLIT_FREE) {
                 /* cur position is not on mark, find nearest mark */
-                cur_win_split = (int) (2 * window_height_shift) / height;
+                cur_win_split = (int) (2 * window_shift) / height;
 
                 /* handle rounding on either side of mid-way mark */
-                if (window_height_shift < 0) {
+                if (window_shift < 0) {
                     cur_win_split--;
                 }
             } else {
@@ -684,17 +755,17 @@ static void decrease_win_height(int jump_or_tty)
             }
 
             /* set window height to specified quarter mark */
-            window_height_shift = (int) (height * (cur_win_split / 2.0));
+            window_shift = (int) (height * (cur_win_split / 2.0));
         }
     } else {
         /* user input: '-' */
         cur_win_split = WIN_SPLIT_FREE; /* cur split is not on a mark */
-        window_height_shift--;  /* decrease src window size by 1 */
+        window_shift--;         /* decrease src window size by 1 */
 
     }
 
     /* reduce flicker by avoiding unnecessary redraws */
-    if (window_height_shift != old_window_height_shift ||
+    if (window_shift != old_window_height_shift ||
             tty_win_height_shift != old_tty_win_height_shift) {
         if_layout();
     }
@@ -1054,7 +1125,7 @@ static void source_input(struct sviewer *sview, int key)
         case CGDB_KEY_CTRL_F:  /* VI-style page down */
             source_vscroll(sview, get_src_height() - 1);
             break;
-        case 'g':              /* beggining of file */
+        case 'g':              /* beginning of file */
             if (last_key_pressed == 'g')
                 source_set_sel_line(sview, 1);
             break;
@@ -1180,7 +1251,7 @@ int if_init(void)
         return 5;
 
     /* Set up window layout */
-    window_height_shift = (int) ((HEIGHT / 2) * (cur_win_split / 2.0));
+    window_shift = (int) ((HEIGHT / 2) * (cur_win_split / 2.0));
     switch (if_layout()) {
         case 2:
             return 4;
@@ -1284,6 +1355,15 @@ int internal_if_input(int key)
                         if_layout();
                     }
 
+                    break;
+                case CGDB_KEY_CTRL_W:
+                    if (cur_split_orientation == SPLIT_HORIZONTAL)
+                        cur_split_orientation = SPLIT_VERTICAL;
+                    else
+                        cur_split_orientation = SPLIT_HORIZONTAL;
+
+                    if_layout();
+
                     break;
                 case CGDB_KEY_F1:
                     if_display_help();
@@ -1535,11 +1615,24 @@ Focus if_get_focus(void)
     return focus;
 }
 
+void reset_window_shift(void)
+{
+    int h_or_w = cur_split_orientation == SPLIT_HORIZONTAL ? HEIGHT : WIDTH;
+
+    window_shift = (int) ((h_or_w / 2) * (cur_win_split / 2.0));
+    if_layout();
+}
+
+void if_set_splitorientation(SPLIT_ORIENTATION_TYPE new_orientation)
+{
+    cur_split_orientation = new_orientation;
+    reset_window_shift();
+}
+
 void if_set_winsplit(WIN_SPLIT_TYPE new_split)
 {
     cur_win_split = new_split;
-    window_height_shift = (int) ((HEIGHT / 2) * (cur_win_split / 2.0));
-    if_layout();
+    reset_window_shift();
 }
 
 void if_highlight_sviewer(enum tokenizer_language_support l)
diff --git a/cgdb/interface.h b/cgdb/interface.h
index 3a6903b3..4de71f0a 100644
--- a/cgdb/interface.h
+++ b/cgdb/interface.h
@@ -163,6 +163,11 @@ void if_tty_toggle(void);
  */
 void if_draw(void);
 
+ /* if_set_winorientation:
+  * ________________
+  */
+void if_set_splitorientation(SPLIT_ORIENTATION_TYPE newOrientation);
+
  /* if_set_winsplit:
   * ________________
   */
diff --git a/doc/cgdb.texinfo b/doc/cgdb.texinfo
index d4160d03..33ec71b6 100644
--- a/doc/cgdb.texinfo
+++ b/doc/cgdb.texinfo
@@ -351,6 +351,9 @@ Opens a window to give input to the debugged program.
 @item Ctrl-T
 Opens a new tty for the debugged program.
 
+@item Ctrl-W
+Toggle the window orientation (horizontal <-> vertical).
+
 @item k
 @itemx up arrow
 Move up a line.
@@ -409,10 +412,10 @@ Sets a breakpoint at the current line number.
 Sets a temporary breakpoint at the current line number.
 
 @item -
-Shrink source window 1 line.
+Shrink source window 1 line or column (depending on split orientation).
 
 @item =
-Grow source window 1 line.
+Grow source window 1 line or column (depending on split orientation).
 
 @item _
 Shrink source window 25% (or, shrink tty window 1 line, if visible).
@@ -678,6 +681,13 @@ as an init setting in your @file{cgdbrc} file.  @xref{Configuring CGDB}.  The
 possible values for @var{style} are @samp{top_full}, @samp{top_big}, 
 @samp{even}, @samp{bottom_big}, and @samp{bottom_full}.
 
+@item :set so=@var{style}
+@itemx :set splitorientation=@var{style}
+Sets the window split orientation to either @samp{horizontal} (which places the 
+source window above and the GDB window below), or @samp{vertical} (which places the 
+source window on the left and the GDB window on the right). 
+@xref{Configuring CGDB}.
+
 @item :set ws
 @itemx :set wrapscan
 Searches wrap around the end of file.  The default is on.