diff --git a/terminaldispatcher.cpp b/terminaldispatcher.cpp
index 76f64e7..d43b2ce 100644
--- a/terminaldispatcher.cpp
+++ b/terminaldispatcher.cpp
@@ -90,6 +90,7 @@ int Dispatcher::getparam( size_t N, int defaultval )
   int ret = defaultval;
   if ( !parsed ) {
     parse_params();
+    parsed = true;
   }
 
   if ( parsed_params.size() > N ) {
@@ -100,6 +101,16 @@ int Dispatcher::getparam( size_t N, int defaultval )
   return ret;
 }
 
+int Dispatcher::param_count( void )
+{
+  if ( !parsed ) {
+    parse_params();
+    parsed = true;
+  }
+
+  return parsed_params.size();
+}
+
 std::string Dispatcher::str( void )
 {
   char assum[ 64 ];
diff --git a/terminaldispatcher.hpp b/terminaldispatcher.hpp
index f72d2e6..81294d1 100644
--- a/terminaldispatcher.hpp
+++ b/terminaldispatcher.hpp
@@ -57,6 +57,7 @@ namespace Terminal {
 
     Dispatcher();
     int getparam( size_t N, int defaultval );
+    int param_count( void );
 
     void newparamchar( Parser::Param *act );
     void collect( Parser::Collect *act );
diff --git a/terminalframebuffer.cpp b/terminalframebuffer.cpp
index b6b74ad..68c17f7 100644
--- a/terminalframebuffer.cpp
+++ b/terminalframebuffer.cpp
@@ -57,8 +57,12 @@ DrawState::DrawState( int s_width, int s_height )
   : width( s_width ), height( s_height ),
     cursor_col( 0 ), cursor_row( 0 ),
     combining_char_col( 0 ), combining_char_row( 0 ), tabs( s_width ),
-    next_print_will_wrap( false ), auto_wrap_mode( true )
-{}
+    next_print_will_wrap( false ), origin_mode( false ), auto_wrap_mode( true )
+{
+  for ( int i = 0; i < width; i++ ) {
+    tabs[ i ] = ( (i % 8) == 0 );
+  }
+}
 
 Framebuffer::Framebuffer( int s_width, int s_height )
   : rows( s_height, Row( s_width ) ), ds( s_width, s_height )
diff --git a/terminalframebuffer.hpp b/terminalframebuffer.hpp
index 91b4ff6..26fc150 100644
--- a/terminalframebuffer.hpp
+++ b/terminalframebuffer.hpp
@@ -44,6 +44,7 @@ namespace Terminal {
 
   public:
     bool next_print_will_wrap;
+    bool origin_mode;
     bool auto_wrap_mode;
 
     /* bold, etc. */
diff --git a/terminalfunctions.cpp b/terminalfunctions.cpp
index 443aed5..ffd76ca 100644
--- a/terminalfunctions.cpp
+++ b/terminalfunctions.cpp
@@ -173,3 +173,36 @@ void CSI_TBC( Framebuffer *fb, Dispatcher *dispatch )
 }
 
 static Function func_CSI_TBC( CSI, "g", CSI_TBC );
+
+static bool *get_DEC_mode( int param, Framebuffer *fb ) {
+  switch ( param ) {
+  case 6: /* origin */
+    return &(fb->ds.origin_mode);
+  case 7: /* auto wrap */
+    return &(fb->ds.auto_wrap_mode);
+  }
+  return NULL;
+}
+
+void CSI_DECSM( Framebuffer *fb, Dispatcher *dispatch )
+{
+  for ( int i = 0; i < dispatch->param_count(); i++ ) {
+    bool *mode = get_DEC_mode( dispatch->getparam( i, 0 ), fb );
+    if ( mode ) {
+      *mode = true;
+    }
+  }
+}
+
+void CSI_DECRM( Framebuffer *fb, Dispatcher *dispatch )
+{
+  for ( int i = 0; i < dispatch->param_count(); i++ ) {
+    bool *mode = get_DEC_mode( dispatch->getparam( i, 0 ), fb );
+    if ( mode ) {
+      *mode = false;
+    }
+  }
+}
+
+static Function func_CSI_DECSM( CSI, "?h", CSI_DECSM );
+static Function func_CSI_DECRM( CSI, "?l", CSI_DECRM );