diff --git a/stix/kernel/Stix.st b/stix/kernel/Stix.st
index b8f314b..96aeb2a 100644
--- a/stix/kernel/Stix.st
+++ b/stix/kernel/Stix.st
@@ -115,6 +115,19 @@
 {
 }
 
+#class(#halfword) LargeInteger(Number)
+{
+}
+
+#class(#halfword) LargePositiveInteger(LargeInteger)
+{
+}
+
+#class(#halfword) LargeNegativeInteger(LargeInteger)
+{
+}
+
+
 #include 'Collection.st'.
 #include 'Collection-ByteArray.st'.
 #include 'Collection-Array.st'.
diff --git a/stix/lib/Makefile.am b/stix/lib/Makefile.am
index dd60648..dee8116 100644
--- a/stix/lib/Makefile.am
+++ b/stix/lib/Makefile.am
@@ -46,6 +46,7 @@ libstix_la_SOURCES = \
 	sym.c \
 	dic.c \
 	proc.c \
+	bigint.c \
 	ignite.c \
 	utf8.c \
 	comp.c \
diff --git a/stix/lib/Makefile.in b/stix/lib/Makefile.in
index 69680b3..0bfc4b9 100644
--- a/stix/lib/Makefile.in
+++ b/stix/lib/Makefile.in
@@ -126,8 +126,9 @@ libstix_la_DEPENDENCIES = $(am__DEPENDENCIES_2)
 am_libstix_la_OBJECTS = libstix_la-stix-rbt.lo libstix_la-stix-utl.lo \
 	libstix_la-stix.lo libstix_la-heap.lo libstix_la-gc.lo \
 	libstix_la-obj.lo libstix_la-sym.lo libstix_la-dic.lo \
-	libstix_la-proc.lo libstix_la-ignite.lo libstix_la-utf8.lo \
-	libstix_la-comp.lo libstix_la-exec.lo libstix_la-debug.lo
+	libstix_la-proc.lo libstix_la-bigint.lo libstix_la-ignite.lo \
+	libstix_la-utf8.lo libstix_la-comp.lo libstix_la-exec.lo \
+	libstix_la-debug.lo
 libstix_la_OBJECTS = $(am_libstix_la_OBJECTS)
 libstix_la_LINK = $(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) \
 	$(LIBTOOLFLAGS) --mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
@@ -381,6 +382,7 @@ libstix_la_SOURCES = \
 	sym.c \
 	dic.c \
 	proc.c \
+	bigint.c \
 	ignite.c \
 	utf8.c \
 	comp.c \
@@ -588,6 +590,7 @@ mostlyclean-compile:
 distclean-compile:
 	-rm -f *.tab.c
 
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libstix_la-bigint.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libstix_la-comp.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libstix_la-debug.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libstix_la-dic.Plo@am__quote@
@@ -696,6 +699,13 @@ libstix_la-proc.lo: proc.c
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
 @am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libstix_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o libstix_la-proc.lo `test -f 'proc.c' || echo '$(srcdir)/'`proc.c
 
+libstix_la-bigint.lo: bigint.c
+@am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libstix_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT libstix_la-bigint.lo -MD -MP -MF $(DEPDIR)/libstix_la-bigint.Tpo -c -o libstix_la-bigint.lo `test -f 'bigint.c' || echo '$(srcdir)/'`bigint.c
+@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libstix_la-bigint.Tpo $(DEPDIR)/libstix_la-bigint.Plo
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='bigint.c' object='libstix_la-bigint.lo' libtool=yes @AMDEPBACKSLASH@
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
+@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libstix_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o libstix_la-bigint.lo `test -f 'bigint.c' || echo '$(srcdir)/'`bigint.c
+
 libstix_la-ignite.lo: ignite.c
 @am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libstix_la_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT libstix_la-ignite.lo -MD -MP -MF $(DEPDIR)/libstix_la-ignite.Tpo -c -o libstix_la-ignite.lo `test -f 'ignite.c' || echo '$(srcdir)/'`ignite.c
 @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libstix_la-ignite.Tpo $(DEPDIR)/libstix_la-ignite.Plo
diff --git a/stix/lib/bigint.c b/stix/lib/bigint.c
new file mode 100644
index 0000000..fbdb0cc
--- /dev/null
+++ b/stix/lib/bigint.c
@@ -0,0 +1,213 @@
+
+#include "stix-prv.h"
+
+/*static normalize_integer (*/
+
+static stix_oop_t normalize (stix_t* stix, stix_oop_t z)
+{
+	return z;
+}
+
+static STIX_INLINE int is_less_unsigned_array (const stix_oohw_t* x, stix_oow_t xs, const stix_oohw_t* y, stix_oow_t ys)
+{
+	stix_oow_t i;
+
+	if (xs != ys) return xs < ys;
+	for (i = xs; i > 0; )
+	{
+		--i;
+		if (x[i] != y[i]) return x[i] < y[i];
+	}
+
+	return 0;
+}
+
+static STIX_INLINE int is_less_unsigned (stix_oop_t x, stix_oop_t y)
+{
+	return is_less_unsigned_array (
+		((stix_oop_halfword_t)x)->slot, STIX_OBJ_GET_SIZE(x), 
+		((stix_oop_halfword_t)y)->slot, STIX_OBJ_GET_SIZE(y));
+}
+
+static STIX_INLINE int is_less (stix_t* stix, stix_oop_t x, stix_oop_t y)
+{
+	if (STIX_OBJ_GET_CLASS(x) != STIX_OBJ_GET_CLASS(y))
+	{
+		return STIX_OBJ_GET_CLASS(x) == stix->_large_negative_integer;
+	}
+
+	return is_less_unsigned (x, y);
+}
+
+static STIX_INLINE int is_equal (stix_t* stix, stix_oop_t x, stix_oop_t y)
+{
+	/* check if two large integers are equal to each other */
+	return STIX_OBJ_GET_CLASS(x) == STIX_OBJ_GET_CLASS(y) && STIX_OBJ_GET_SIZE(x) == STIX_OBJ_GET_SIZE(y) &&
+	       STIX_MEMCMP(((stix_oop_halfword_t)x)->slot,  ((stix_oop_halfword_t)y)->slot, STIX_OBJ_GET_SIZE(x) * STIX_SIZEOF(stix_oohw_t)) == 0;
+}
+
+static STIX_INLINE stix_oow_t add_unsigned_array (const stix_oohw_t* x, stix_oow_t xs, const stix_oohw_t* y, stix_oow_t ys, stix_oohw_t* z)
+{
+	stix_oow_t i, w;
+	stix_oow_t carry = 0;
+
+	STIX_ASSERT (xs >= ys);
+
+	for (i = 0; i < ys; i++)
+	{
+		w = (stix_oow_t)x[i] + (stix_oow_t)y[i] + carry;
+		carry = w >> STIX_OOHW_BITS;
+		z[i] = w & STIX_LBMASK(stix_oow_t, STIX_OOHW_BITS);
+	}
+	
+	for (; i < xs; i++)
+	{
+		w = (stix_oow_t)x[i] + carry;
+		carry = w >> STIX_OOHW_BITS;
+		z[i] = w & STIX_LBMASK(stix_oow_t, STIX_OOHW_BITS);
+	}
+
+	if (i > 1 && carry == 0) return i - 1;
+	z[i] = carry;
+	return i;
+}
+
+
+static STIX_INLINE stix_oow_t subtract_unsigned_array (const stix_oohw_t* x, stix_oow_t xs, const stix_oohw_t* y, stix_oow_t ys, stix_oohw_t* z)
+{
+	stix_oow_t i, w;
+	stix_oow_t borrow = 0;
+	stix_oow_t borrowed_word;
+
+	STIX_ASSERT (!is_less_unsigned_array(x, xs, y, ys));
+
+	borrowed_word = (stix_oow_t)1 << STIX_OOHW_BITS;
+	for (i = 0; i < ys; i++)
+	{
+		w = (stix_oow_t)y[i] + borrow;
+		if ((stix_oow_t)x[i] >= w)
+		{
+			z[i] = x[i] - w;
+			borrow = 0;
+		}
+		else
+		{
+			z[i] = (borrowed_word + (stix_oow_t)x[i]) - w; 
+			borrow = 1;
+		}
+	}
+
+	for (; i < xs; i++)
+	{
+		if (x[i] >= borrow) 
+		{
+			z[i] = x[i] - (stix_oohw_t)borrow;
+			borrow = 0;
+		}
+		else
+		{
+			z[i] = (borrowed_word + (stix_oow_t)x[i]) - borrow;
+			borrow = 1;
+		}
+	}
+
+	STIX_ASSERT (borrow == 0);
+	return i;
+}
+
+static stix_oop_t add_unsigned_integers (stix_t* stix, stix_oop_t x, stix_oop_t y)
+{
+	stix_oohw_t* a, * b;
+	stix_oow_t as, bs, zs, ks;
+	stix_oop_t z;
+
+	as = STIX_OBJ_GET_SIZE(x);
+	bs = STIX_OBJ_GET_SIZE(y);
+	zs = (as >= bs? as: bs) + 1;
+
+	stix_pushtmp (stix, &x);
+	stix_pushtmp (stix, &y);
+	z = stix_instantiate (stix, STIX_OBJ_GET_CLASS(x), STIX_NULL, zs);
+	stix_poptmps (stix, 2);
+
+	if (as >= bs)
+	{
+		a = ((stix_oop_halfword_t)x)->slot;
+		b = ((stix_oop_halfword_t)y)->slot;
+	}
+	else 
+	{
+		a = ((stix_oop_halfword_t)y)->slot;
+		b = ((stix_oop_halfword_t)x)->slot;
+	}
+
+	ks = add_unsigned_array (a, as, b, bs, ((stix_oop_halfword_t)z)->slot);
+	if (ks <= zs)
+	{
+		/*normalize;*/
+	}
+
+	return z;
+}
+
+static stix_oop_t subtract_unsigned_integers (stix_t* stix, stix_oop_t x, stix_oop_t y)
+{
+	stix_oop_t z;
+
+	stix_pushtmp (stix, &x);
+	stix_pushtmp (stix, &y);
+	z = stix_instantiate (stix, stix->_large_positive_integer, STIX_NULL, STIX_OBJ_GET_SIZE(x));
+	stix_poptmps (stix, 2);
+
+	subtract_unsigned_array (
+		((stix_oop_halfword_t)x)->slot, STIX_OBJ_GET_SIZE(x),
+		((stix_oop_halfword_t)y)->slot, STIX_OBJ_GET_SIZE(y),
+		((stix_oop_halfword_t)z)->slot);
+	return z;
+}
+
+
+stix_oop_t stix_addbigints (stix_t* stix, stix_oop_t x, stix_oop_t y)
+{
+	stix_oop_t z;
+
+	if (STIX_OBJ_GET_CLASS(x) != STIX_OBJ_GET_CLASS(y))
+	{
+		if (STIX_OBJ_GET_CLASS(x) == stix->_large_negative_integer)
+			z = stix_subbigints (stix, y, x);
+		else
+			z = stix_subbigints (stix, x, y);
+	}
+	else
+	{
+		z = add_unsigned_integers (stix, x, y);
+	}
+
+	return normalize(stix, z);
+}
+
+#if 0
+stix_subbigints (stix_t* stix, stix_oop_t x, stix_oop_t y)
+{
+/* TOOD: ensure both are LargeIntgers */
+
+	if (STIX_OBJ_GET_CLASS(x) != STIX_OBJ_GET_CLASS(y))
+	{
+		z = add_unsigned (stix, x, y);
+	}
+	else
+	{
+		if (is_less_unsigned (x, y))
+		{
+			z = subtract_unsigned (stix, y, x); /* get the opposite sign of x; */
+		}
+		else
+		{
+			
+			z = subtract_unsigned (stix, x, y); /* take x's sign */
+		}
+	}
+
+	return normalize (stix, z);
+}
+#endif
diff --git a/stix/lib/comp.c b/stix/lib/comp.c
index 33e2d7e..dddff80 100644
--- a/stix/lib/comp.c
+++ b/stix/lib/comp.c
@@ -89,6 +89,7 @@ static struct voca_t
 	{  7, { 'd','e','c','l','a','r','e'                                   } },
 	{  6, { 'e','x','t','e','n','d'                                       } },
 	{  5, { 'f','a','l','s','e'                                           } },
+	{  8, { 'h','a','l','f','w','o','r','d'                               } },
 	{  7, { 'i','n','c','l','u','d','e'                                   } },
 	{  4, { 'm','a','i','n'                                               } },
 	{  6, { 'm','e','t','h','o','d'                                       } },
@@ -120,6 +121,7 @@ enum voca_id_t
 	VOCA_DECLARE,
 	VOCA_EXTEND,
 	VOCA_FALSE,
+	VOCA_HALFWORD,
 	VOCA_INCLUDE,
 	VOCA_MAIN,
 	VOCA_METHOD,
@@ -1582,14 +1584,14 @@ static int end_include (stix_t* stix)
  * Byte-Code Generator
  * --------------------------------------------------------------------- */
 
-static STIX_INLINE int emit_byte_instruction (stix_t* stix, stix_byte_t code)
+static STIX_INLINE int emit_byte_instruction (stix_t* stix, stix_oob_t code)
 {
 	stix_size_t i;
 
 	i = stix->c->mth.code.len + 1;
 	if (i > stix->c->mth.code_capa)
 	{
-		stix_byte_t* tmp;
+		stix_oob_t* tmp;
 
 		i = STIX_ALIGN (i, CODE_BUFFER_ALIGN);
 
@@ -1606,7 +1608,7 @@ static STIX_INLINE int emit_byte_instruction (stix_t* stix, stix_byte_t code)
 
 static int emit_single_param_instruction (stix_t* stix, int cmd, stix_oow_t param_1)
 {
-	stix_byte_t bc;
+	stix_oob_t bc;
 
 	switch (cmd)
 	{
@@ -1619,7 +1621,7 @@ static int emit_single_param_instruction (stix_t* stix, int cmd, stix_oow_t para
 		case BCODE_PUSH_LITERAL_0:
 			if (param_1 < 8)
 			{
-				bc = (stix_byte_t)(cmd & 0xF8) | (stix_byte_t)param_1;
+				bc = (stix_oob_t)(cmd & 0xF8) | (stix_oob_t)param_1;
 				goto write_short;
 			}
 			else
@@ -1638,7 +1640,7 @@ static int emit_single_param_instruction (stix_t* stix, int cmd, stix_oow_t para
 		case BCODE_JUMP_IF_FALSE_0:
 			if (param_1 < 4)
 			{
-				bc = (stix_byte_t)(cmd & 0xFC) | (stix_byte_t)param_1;
+				bc = (stix_oob_t)(cmd & 0xFC) | (stix_oob_t)param_1;
 				goto write_short;
 			}
 			else
@@ -1678,7 +1680,7 @@ write_long:
 
 static int emit_double_param_instruction (stix_t* stix, int cmd, stix_size_t param_1, stix_size_t param_2)
 {
-	stix_byte_t bc;
+	stix_oob_t bc;
 
 	switch (cmd)
 	{
@@ -1693,7 +1695,7 @@ static int emit_double_param_instruction (stix_t* stix, int cmd, stix_size_t par
 			if (param_1 < 8 && param_2 < 0xFF)
 			{
 				/* low 2 bits of the instruction code is the first parameter */
-				bc = (stix_byte_t)(cmd & 0xFC) | (stix_byte_t)param_1;
+				bc = (stix_oob_t)(cmd & 0xFC) | (stix_oob_t)param_1;
 				goto write_short;
 			}
 			else
@@ -3073,15 +3075,15 @@ printf ("\tfixed jump offset to %u\n", (unsigned int)jump_offset);
 }
 
 
-static int add_to_balit_buffer (stix_t* stix, stix_byte_t b)
+static int add_to_balit_buffer (stix_t* stix, stix_oob_t b)
 {
 	if (stix->c->mth.balit_count >= stix->c->mth.balit_capa)
 	{
-		stix_byte_t* tmp;
+		stix_oob_t* tmp;
 		stix_size_t new_capa;
 
 		new_capa = STIX_ALIGN (stix->c->mth.balit_count + 1, BALIT_BUFFER_ALIGN);
-		tmp = (stix_byte_t*)stix_reallocmem (stix, stix->c->mth.balit, new_capa * STIX_SIZEOF(*tmp));
+		tmp = (stix_oob_t*)stix_reallocmem (stix, stix->c->mth.balit, new_capa * STIX_SIZEOF(*tmp));
 		if (!tmp) return -1;
 
 		stix->c->mth.balit_capa = new_capa;
@@ -3563,7 +3565,7 @@ printf ("\tpush int literal\n");
 	return 0;
 }
 
-static stix_byte_t send_message_cmd[] = 
+static stix_oob_t send_message_cmd[] = 
 {
 	BCODE_SEND_MESSAGE_0,
 	BCODE_SEND_MESSAGE_TO_SUPER_0
@@ -4472,6 +4474,13 @@ static int __compile_class_definition (stix_t* stix, int extend)
 			stix->c->cls.indexed_type = STIX_OBJ_TYPE_CHAR;
 			GET_TOKEN (stix);
 		}
+		else if (is_token_symbol(stix, VOCA_HALFWORD))
+		{
+			/* #class(#halfword) */
+			stix->c->cls.flags |= CLASS_INDEXED;
+			stix->c->cls.indexed_type = STIX_OBJ_TYPE_HALFWORD;
+			GET_TOKEN (stix);
+		}
 		else if (is_token_symbol(stix, VOCA_WORD))
 		{
 			/* #class(#word) */
diff --git a/stix/lib/debug.c b/stix/lib/debug.c
index b407df7..4f6f6f1 100644
--- a/stix/lib/debug.c
+++ b/stix/lib/debug.c
@@ -278,6 +278,15 @@ static void __dump_object (stix_t* stix, stix_oop_t oop, int depth)
 			}
 			printf ("]");
 		}
+		else if (STIX_OBJ_GET_FLAGS_TYPE(oop) == STIX_OBJ_TYPE_HALFWORD)
+		{
+			printf (" #["); /* TODO: different symbol for word array ?? */
+			for (i = 0; i < STIX_OBJ_GET_SIZE(oop); i++)
+			{
+				printf (" %ld", (long int)((stix_oop_halfword_t)oop)->slot[i]);
+			}
+			printf ("]");
+		}
 		else if (STIX_OBJ_GET_FLAGS_TYPE(oop) == STIX_OBJ_TYPE_WORD)
 		{
 			printf (" #["); /* TODO: different symbol for word array ?? */
diff --git a/stix/lib/exec.c b/stix/lib/exec.c
index be45f33..113ec07 100644
--- a/stix/lib/exec.c
+++ b/stix/lib/exec.c
@@ -673,6 +673,11 @@ static int prim_basic_at (stix_t* stix, stix_ooi_t nargs)
 			v = STIX_OOP_FROM_CHAR(((stix_oop_char_t)rcv)->slot[idx]);
 			break;
 
+		case STIX_OBJ_TYPE_HALFWORD:
+			/* TODO: LargeInteger if the halfword is too large */
+			v = STIX_OOP_FROM_SMINT(((stix_oop_halfword_t)rcv)->slot[idx]);
+			break;
+
 		case STIX_OBJ_TYPE_WORD:
 			/* TODO: LargeInteger if the word is too large */
 			v = STIX_OOP_FROM_SMINT(((stix_oop_word_t)rcv)->slot[idx]);
@@ -739,7 +744,6 @@ static int prim_basic_at_put (stix_t* stix, stix_ooi_t nargs)
 /* TOOD: must I check the range of the value? */
 			((stix_oop_char_t)rcv)->slot[idx] = STIX_OOP_TO_SMINT(val);
 			break;
-		
 
 		case STIX_OBJ_TYPE_CHAR:
 			if (!STIX_OOP_IS_CHAR(val))
@@ -750,14 +754,25 @@ static int prim_basic_at_put (stix_t* stix, stix_ooi_t nargs)
 			((stix_oop_char_t)rcv)->slot[idx] = STIX_OOP_TO_CHAR(val);
 			break;
 
+		case STIX_OBJ_TYPE_HALFWORD:
+			if (!STIX_OOP_IS_SMINT(val))
+			{
+				/* the value is not a number */
+				return 0;
+			}
+
+			/* if the small integer is too large, it will get truncated */
+			((stix_oop_halfword_t)rcv)->slot[idx] = STIX_OOP_TO_SMINT(val);
+			break;
+
 		case STIX_OBJ_TYPE_WORD:
 			/* TODO: handle largeINteger  */
 			if (!STIX_OOP_IS_SMINT(val))
 			{
-				/* the value is not a character */
+				/* the value is not a number */
 				return 0;
 			}
-			((stix_oop_char_t)rcv)->slot[idx] = STIX_OOP_TO_SMINT(val);
+			((stix_oop_word_t)rcv)->slot[idx] = STIX_OOP_TO_SMINT(val);
 			break;
 
 		case STIX_OBJ_TYPE_OOP:
@@ -1727,7 +1742,7 @@ done:
 
 int stix_execute (stix_t* stix)
 {
-	stix_byte_t bcode;
+	stix_oob_t bcode;
 	stix_ooi_t b1, b2;
 	stix_oop_t return_value;
 
diff --git a/stix/lib/gc.c b/stix/lib/gc.c
index c5e71e9..0bdee01 100644
--- a/stix/lib/gc.c
+++ b/stix/lib/gc.c
@@ -289,8 +289,10 @@ void stix_gc (stix_t* stix)
 	stix->_true_class        = stix_moveoop (stix, stix->_true_class);
 	stix->_false_class       = stix_moveoop (stix, stix->_false_class);
 	stix->_character         = stix_moveoop (stix, stix->_character);
-	stix->_small_integer     = stix_moveoop (stix, stix->_small_integer);
-	stix->_large_integer     = stix_moveoop (stix, stix->_large_integer);
+
+	stix->_small_integer          = stix_moveoop (stix, stix->_small_integer);
+	stix->_large_positive_integer = stix_moveoop (stix, stix->_large_positive_integer);
+	stix->_large_negative_integer = stix_moveoop (stix, stix->_large_negative_integer);
 
 	stix->sysdic = (stix_oop_set_t) stix_moveoop (stix, (stix_oop_t)stix->sysdic);
 	stix->processor = (stix_oop_process_scheduler_t) stix_moveoop (stix, (stix_oop_t)stix->processor);
diff --git a/stix/lib/ignite.c b/stix/lib/ignite.c
index fbe9167..bb1fbf1 100644
--- a/stix/lib/ignite.c
+++ b/stix/lib/ignite.c
@@ -62,6 +62,8 @@
  *               Integer
  *                  SmallInteger
  *                  LargeInteger
+ *                     LargePositiveInteger
+ *                     LargeNegativeInteger
  * 
  * Stix has no instance variables.
  * Stix has 1 class variable: Sysdic
@@ -143,7 +145,8 @@ static int ignite_1 (stix_t* stix)
 	 *       Does this make sense? */
 	stix->_character         = alloc_kernel_class (stix, 0, STIX_CLASS_SPEC_MAKE(0, 0, STIX_OBJ_TYPE_OOP));
 	stix->_small_integer     = alloc_kernel_class (stix, 0, STIX_CLASS_SPEC_MAKE(0, 0, STIX_OBJ_TYPE_OOP));
-	stix->_large_integer     = alloc_kernel_class (stix, 0, STIX_CLASS_SPEC_MAKE(0, 1, STIX_OBJ_TYPE_OOP));
+	stix->_large_positive_integer = alloc_kernel_class (stix, 0, STIX_CLASS_SPEC_MAKE(0, 1, STIX_OBJ_TYPE_HALFWORD));
+	stix->_large_negative_integer = alloc_kernel_class (stix, 0, STIX_CLASS_SPEC_MAKE(0, 1, STIX_OBJ_TYPE_HALFWORD));
 
 	if (!stix->_apex              || !stix->_undefined_object  || 
 	    !stix->_object            || !stix->_string            ||
@@ -158,7 +161,8 @@ static int ignite_1 (stix_t* stix)
 	    !stix->_process           || !stix->_process_scheduler ||
 
 	    !stix->_true_class        || !stix->_false_class       || 
-	    !stix->_character         || !stix->_small_integer     || !stix->_large_integer) return -1;
+	    !stix->_character         || !stix->_small_integer     || 
+	    !stix->_large_positive_integer  || !stix->_large_negative_integer) return -1;
 
 	STIX_OBJ_SET_CLASS (stix->_nil, stix->_undefined_object);
 	return 0;
@@ -213,7 +217,7 @@ static int ignite_3 (stix_t* stix)
 	static struct symbol_name_t
 	{
 		stix_oow_t len;
-		stix_ooch_t str[16];
+		stix_ooch_t str[20];
 	} symnames[] = {
 		{  4, { 'A','p','e','x'                                                  } },
 		{ 15, { 'U','n','d','e','f','i','n','e','d','O','b','j','e','c','t'      } },
@@ -241,7 +245,8 @@ static int ignite_3 (stix_t* stix)
 		{  5, { 'F','a','l','s','e'                                              } },
 		{  9, { 'C','h','a','r','a','c','t','e','r'                              } },
 		{ 12, { 'S','m','a','l','l','I','n','t','e','g','e','r'                  } },
-		{ 12, { 'L','a','r','g','e','I','n','t','e','g','e','r'                  } }
+		{ 20, { 'L','a','r','g','e','P','o','s','i','t','i','v','e','I','n','t','e','g','e','r' } },
+		{ 20, { 'L','a','r','g','e','N','e','g','a','t','i','v','e','I','n','t','e','g','e','r' } }
 	};
 
 	static stix_ooch_t str_stix[] = { 'S','t','i','x' };
diff --git a/stix/lib/obj.c b/stix/lib/obj.c
index 912e1a0..3fcb695 100644
--- a/stix/lib/obj.c
+++ b/stix/lib/obj.c
@@ -74,7 +74,7 @@ stix_oop_t stix_allocoopobj (stix_t* stix, stix_oow_t size)
 }
 
 #if defined(STIX_USE_OBJECT_TRAILER)
-stix_oop_t stix_allocoopobjwithtrailer (stix_t* stix, stix_oow_t size, const stix_byte_t* bptr, stix_oow_t blen)
+stix_oop_t stix_allocoopobjwithtrailer (stix_t* stix, stix_oow_t size, const stix_oob_t* bptr, stix_oow_t blen)
 {
 	stix_oop_oop_t hdr;
 	stix_oow_t nbytes, nbytes_aligned;
@@ -163,9 +163,9 @@ stix_oop_t stix_allocmbcharobj (stix_t* stix, const stix_ooch_t* ptr, stix_oow_t
 }
 */
 
-stix_oop_t stix_allocbyteobj (stix_t* stix, const stix_byte_t* ptr, stix_oow_t len)
+stix_oop_t stix_allocbyteobj (stix_t* stix, const stix_oob_t* ptr, stix_oow_t len)
 {
-	return alloc_numeric_array (stix, ptr, len, STIX_OBJ_TYPE_BYTE, STIX_SIZEOF(stix_byte_t), 0);
+	return alloc_numeric_array (stix, ptr, len, STIX_OBJ_TYPE_BYTE, STIX_SIZEOF(stix_oob_t), 0);
 }
 
 stix_oop_t stix_allocwordobj (stix_t* stix, const stix_oow_t* ptr, stix_oow_t len)
@@ -272,7 +272,7 @@ einval:
 
 #if defined(STIX_USE_OBJECT_TRAILER)
 
-stix_oop_t stix_instantiatewithtrailer (stix_t* stix, stix_oop_t _class, stix_oow_t vlen, const stix_byte_t* tptr, stix_oow_t tlen)
+stix_oop_t stix_instantiatewithtrailer (stix_t* stix, stix_oop_t _class, stix_oow_t vlen, const stix_oob_t* tptr, stix_oow_t tlen)
 {
 	stix_oop_t oop;
 	stix_oow_t spec;
diff --git a/stix/lib/stix-cmn.h b/stix/lib/stix-cmn.h
index 5124e7e..40475c9 100644
--- a/stix/lib/stix-cmn.h
+++ b/stix/lib/stix-cmn.h
@@ -226,7 +226,6 @@
 
 typedef stix_uintptr_t stix_size_t;
 typedef stix_intptr_t stix_ssize_t;
-typedef stix_uint8_t  stix_byte_t;
 
 typedef char          stix_bch_t;
 typedef stix_uint16_t stix_uch_t; /* TODO ... wchar_t??? */
@@ -438,4 +437,24 @@ struct stix_cmgr_t
 #endif
 
 
+
+
+/* =========================================================================
+ * BASIC STIX TYPES
+ * =========================================================================*/
+
+typedef stix_uint8_t             stix_oob_t;
+/* NOTE: sizeof(stix_oop_t) must be equal to sizeof(stix_oow_t) */
+typedef stix_uintptr_t           stix_oow_t;
+typedef stix_intptr_t            stix_ooi_t;
+
+typedef stix_ushortptr_t         stix_oohw_t; /* half word - half word */
+typedef stix_shortptr_t          stix_oohi_t; /* signed half word */
+
+typedef stix_uch_t               stix_ooch_t;
+typedef stix_uci_t               stix_ooci_t;
+typedef stix_ucs_t               stix_oocs_t;
+#define STIX_OOCH_IS_UCH
+
+
 #endif
diff --git a/stix/lib/stix-prv.h b/stix/lib/stix-prv.h
index 64baaa5..cb16378 100644
--- a/stix/lib/stix-prv.h
+++ b/stix/lib/stix-prv.h
@@ -475,7 +475,7 @@ struct stix_compiler_t
 		stix_size_t literal_capa;
 
 		/* byte array elements */
-		stix_byte_t* balit;
+		stix_oob_t* balit;
 		stix_size_t balit_count;
 		stix_size_t balit_capa;
 
@@ -504,7 +504,7 @@ struct stix_compiler_t
 
 #if defined(STIX_USE_OBJECT_TRAILER)
 	/* let it point to the trailer of the method */
-#	define SET_ACTIVE_METHOD_CODE(stix) ((stix)->active_code = (stix_byte_t*)&(stix)->active_method->slot[STIX_OBJ_GET_SIZE((stix)->active_method) + 1 - STIX_METHOD_NAMED_INSTVARS])
+#	define SET_ACTIVE_METHOD_CODE(stix) ((stix)->active_code = (stix_oob_t*)&(stix)->active_method->slot[STIX_OBJ_GET_SIZE((stix)->active_method) + 1 - STIX_METHOD_NAMED_INSTVARS])
 #else
 	/* let it point to the payload of the code byte array */
 #	define SET_ACTIVE_METHOD_CODE(stix) ((stix)->active_code = (stix)->active_method->code->slot)
@@ -808,23 +808,6 @@ enum stix_bcode_t
 extern "C" {
 #endif
 
-#if defined(STIX_OOCH_IS_UCH)
-#	define stix_hashchars(ptr,len) stix_hashuchars(ptr,len)
-#	define stix_compoocbcstr(str1,str2) stix_compucbcstr(str1,str2)
-#	define stix_compoocstr(str1,str2) stix_compucstr(str1,str2)
-#	define stix_copyoochars(dst,src,len) stix_copyuchars(dst,src,len)
-#	define stix_copybchtooochars(dst,src,len) stix_copybchtouchars(dst,src,len)
-#	define stix_copyoocstr(dst,len,src) stix_copyucstr(dst,len,src)
-#	define stix_findoochar(ptr,len,c) stix_finduchar(ptr,len,c)
-#else
-#	define stix_hashchars(ptr,len) stix_hashbchars(ptr,len)
-#	define stix_compoocbcstr(str1,str2) stix_compbcstr(str1,str2)
-#	define stix_compoocstr(str1,str2) stix_compbcstr(str1,str2)
-#	define stix_copyoochars(dst,src,len) stix_copybchars(dst,src,len)
-#	define stix_copybchtooochars(dst,src,len) stix_copybchars(dst,src,len)
-#	define stix_copyoocstr(dst,len,src) stix_copybcstr(dst,len,src)
-#	define stix_findoochar(ptr,len,c) stix_findbchar(ptr,len,c)
-#endif
 
 /* ========================================================================= */
 /* heap.c                                                                    */
@@ -890,7 +873,7 @@ stix_oop_t stix_allocoopobj (
 stix_oop_t stix_allocoopobjwithtrailer (
 	stix_t*            stix,
 	stix_oow_t         size,
-	const stix_byte_t* tptr,
+	const stix_oob_t* tptr,
 	stix_oow_t         tlen
 );
 #endif
@@ -903,7 +886,7 @@ stix_oop_t stix_alloccharobj (
 
 stix_oop_t stix_allocbyteobj (
 	stix_t*            stix,
-	const stix_byte_t* ptr,
+	const stix_oob_t* ptr,
 	stix_oow_t         len
 );
 
@@ -918,7 +901,7 @@ stix_oop_t stix_instantiatewithtrailer (
 	stix_t*            stix, 
 	stix_oop_t         _class,
 	stix_oow_t         vlen,
-	const stix_byte_t* tptr,
+	const stix_oob_t* tptr,
 	stix_oow_t tlen
 );
 #endif
@@ -1052,6 +1035,21 @@ int stix_utf8toucs (
 	stix_size_t*        ucslen
 );
 
+/* ========================================================================= */
+/* bigint.c                                                                    */
+/* ========================================================================= */
+stix_oop_t stix_addbigints (
+	stix_t*    stix,
+	stix_oop_t x,
+	stix_oop_t y
+);
+
+stix_oop_t stix_subbigints (
+	stix_t*    stix,
+	stix_oop_t x,
+	stix_oop_t y
+);
+
 /* ========================================================================= */
 /* comp.c                                                                    */
 /* ========================================================================= */
diff --git a/stix/lib/stix-utl.c b/stix/lib/stix-utl.c
index 60fc7f1..6b67b14 100644
--- a/stix/lib/stix-utl.c
+++ b/stix/lib/stix-utl.c
@@ -27,7 +27,7 @@
 
 #include "stix-utl.h"
 
-stix_size_t stix_hashbytes (const stix_byte_t* ptr, stix_size_t len)
+stix_size_t stix_hashbytes (const stix_oob_t* ptr, stix_size_t len)
 {
 	stix_size_t h = 0;
 	const stix_uint8_t* bp, * be;
@@ -40,7 +40,7 @@ stix_size_t stix_hashbytes (const stix_byte_t* ptr, stix_size_t len)
 
 stix_size_t stix_hashuchars (const stix_uch_t* ptr, stix_size_t len)
 {
-	return stix_hashbytes ((const stix_byte_t *)ptr, len * STIX_SIZEOF(*ptr));
+	return stix_hashbytes ((const stix_oob_t *)ptr, len * STIX_SIZEOF(*ptr));
 }
 
 int stix_equalchars (const stix_uch_t* str1, const stix_uch_t* str2, stix_size_t len)
diff --git a/stix/lib/stix-utl.h b/stix/lib/stix-utl.h
index 920de00..cc2177f 100644
--- a/stix/lib/stix-utl.h
+++ b/stix/lib/stix-utl.h
@@ -33,12 +33,30 @@
 extern "C" {
 #endif
 
+#if defined(STIX_OOCH_IS_UCH)
+#	define stix_hashchars(ptr,len) stix_hashuchars(ptr,len)
+#	define stix_compoocbcstr(str1,str2) stix_compucbcstr(str1,str2)
+#	define stix_compoocstr(str1,str2) stix_compucstr(str1,str2)
+#	define stix_copyoochars(dst,src,len) stix_copyuchars(dst,src,len)
+#	define stix_copybchtooochars(dst,src,len) stix_copybchtouchars(dst,src,len)
+#	define stix_copyoocstr(dst,len,src) stix_copyucstr(dst,len,src)
+#	define stix_findoochar(ptr,len,c) stix_finduchar(ptr,len,c)
+#else
+#	define stix_hashchars(ptr,len) stix_hashbchars(ptr,len)
+#	define stix_compoocbcstr(str1,str2) stix_compbcstr(str1,str2)
+#	define stix_compoocstr(str1,str2) stix_compbcstr(str1,str2)
+#	define stix_copyoochars(dst,src,len) stix_copybchars(dst,src,len)
+#	define stix_copybchtooochars(dst,src,len) stix_copybchars(dst,src,len)
+#	define stix_copyoocstr(dst,len,src) stix_copybcstr(dst,len,src)
+#	define stix_findoochar(ptr,len,c) stix_findbchar(ptr,len,c)
+#endif
+
 
 /* ========================================================================= */
 /* stix-utl.c                                                                */
 /* ========================================================================= */
 stix_size_t stix_hashbytes (
-	const stix_byte_t* ptr,
+	const stix_oob_t* ptr,
 	stix_size_t        len
 );
 
diff --git a/stix/lib/stix.h b/stix/lib/stix.h
index c70189e..611c98c 100644
--- a/stix/lib/stix.h
+++ b/stix/lib/stix.h
@@ -75,33 +75,26 @@ enum stix_trait_t
 };
 typedef enum stix_trait_t stix_trait_t;
 
-/* NOTE: sizeof(stix_oop_t) must be equal to sizeof(stix_oow_t) */
-typedef stix_uintptr_t           stix_oow_t;
-typedef stix_intptr_t            stix_ooi_t;
-typedef stix_ushortptr_t         stix_oosw_t; /* short word - half word */
-typedef stix_shortptr_t          stix_oosi_t; /* signed short word */
-typedef struct stix_obj_t        stix_obj_t;
-typedef struct stix_obj_t*       stix_oop_t;
-
-typedef stix_uch_t               stix_ooch_t;
-typedef stix_uci_t               stix_ooci_t;
-typedef stix_ucs_t               stix_oocs_t;
-#define STIX_OOCH_IS_UCH
+typedef struct stix_obj_t           stix_obj_t;
+typedef struct stix_obj_t*          stix_oop_t;
 
 /* these are more specialized types for stix_obj_t */
-typedef struct stix_obj_oop_t     stix_obj_oop_t;
-typedef struct stix_obj_char_t    stix_obj_char_t;
-typedef struct stix_obj_byte_t    stix_obj_byte_t;
-typedef struct stix_obj_word_t    stix_obj_word_t;
+typedef struct stix_obj_oop_t       stix_obj_oop_t;
+typedef struct stix_obj_char_t      stix_obj_char_t;
+typedef struct stix_obj_byte_t      stix_obj_byte_t;
+typedef struct stix_obj_halfword_t  stix_obj_halfword_t;
+typedef struct stix_obj_word_t      stix_obj_word_t;
 
 /* these are more specialized types for stix_oop_t */
-typedef struct stix_obj_oop_t*    stix_oop_oop_t;
-typedef struct stix_obj_char_t*   stix_oop_char_t;
-typedef struct stix_obj_byte_t*   stix_oop_byte_t;
-typedef struct stix_obj_word_t*   stix_oop_word_t;
+typedef struct stix_obj_oop_t*      stix_oop_oop_t;
+typedef struct stix_obj_char_t*     stix_oop_char_t;
+typedef struct stix_obj_byte_t*     stix_oop_byte_t;
+typedef struct stix_obj_halfword_t* stix_oop_halfword_t;
+typedef struct stix_obj_word_t*     stix_oop_word_t;
 
-#define STIX_OOW_BITS (STIX_SIZEOF(stix_oow_t) * 8)
-#define STIX_OOP_BITS (STIX_SIZEOF(stix_oop_t) * 8)
+#define STIX_OOW_BITS  (STIX_SIZEOF(stix_oow_t) * 8)
+#define STIX_OOP_BITS  (STIX_SIZEOF(stix_oop_t) * 8)
+#define STIX_OOHW_BITS (STIX_SIZEOF(stix_oohw_t) * 8)
 
 /* 
  * OOP encoding
@@ -152,7 +145,9 @@ enum stix_obj_type_t
 	STIX_OBJ_TYPE_OOP,
 	STIX_OBJ_TYPE_CHAR,
 	STIX_OBJ_TYPE_BYTE,
-	STIX_OBJ_TYPE_WORD
+	STIX_OBJ_TYPE_HALFWORD,
+	STIX_OBJ_TYPE_WORD,
+	
 
 /*
 	STIX_OBJ_TYPE_UINT8,
@@ -178,7 +173,7 @@ typedef enum stix_obj_type_t stix_obj_type_t;
  * _flags:
  *   type: the type of a payload item. 
  *         one of STIX_OBJ_TYPE_OOP, STIX_OBJ_TYPE_CHAR, 
- *                STIX_OBJ_TYPE_BYTE, STIX_OBJ_TYPE_WORD
+ *                STIX_OBJ_TYPE_BYTE, STIX_OBJ_TYPE_HALFWORD, STIX_OBJ_TYPE_WORD
  *   unit: the size of a payload item in bytes. 
  *   extra: 0 or 1. 1 indicates that the payload contains 1 more
  *          item than the value of the size field. used for a 
@@ -283,7 +278,13 @@ struct stix_obj_char_t
 struct stix_obj_byte_t
 {
 	STIX_OBJ_HEADER;
-	stix_byte_t slot[1];
+	stix_oob_t slot[1];
+};
+
+struct stix_obj_halfword_t
+{
+	STIX_OBJ_HEADER;
+	stix_oohw_t slot[1];
 };
 
 struct stix_obj_word_t
@@ -296,7 +297,7 @@ typedef struct stix_trailer_t stix_trailer_t;
 struct stix_trailer_t
 {
 	stix_oow_t size;
-	stix_byte_t slot[1];
+	stix_oob_t slot[1];
 };
 
 #define STIX_SET_NAMED_INSTVARS 2
@@ -679,7 +680,8 @@ struct stix_t
 	stix_oop_t _character; /* Character */
 
 	stix_oop_t _small_integer; /* SmallInteger */
-	stix_oop_t _large_integer;
+	stix_oop_t _large_positive_integer; /* LargePositiveInteger */
+	stix_oop_t _large_negative_integer; /* LargeNegativeInteger */
 	/* == NEVER CHANGE THE ORDER OF FIELDS ABOVE == */
 
 	stix_oop_set_t symtab; /* system-wide symbol table. instance of SymbolSet */
@@ -692,7 +694,7 @@ struct stix_t
 	/* == EXECUTION REGISTERS == */
 	stix_oop_context_t active_context;
 	stix_oop_method_t active_method;
-	stix_byte_t* active_code;
+	stix_oob_t* active_code;
 	stix_ooi_t sp;
 	stix_ooi_t ip;
 	/* == END EXECUTION REGISTERS == */