diff --git a/moo/kernel/Magnitu.moo b/moo/kernel/Magnitu.moo
index 3a9d879..2f19d97 100644
--- a/moo/kernel/Magnitu.moo
+++ b/moo/kernel/Magnitu.moo
@@ -45,10 +45,8 @@ class Association(Magnitude)
 
 class(#limited) Character(Magnitude)
 {
-	## method basicSize
-	## {
-	## 	^0
-	## }
+##	method(#primitive,#class) fromCode: code.
+##	method(#primitive) toCode.
 
 	method(#primitive) asInteger.
 
diff --git a/moo/kernel/Socket.moo b/moo/kernel/Socket.moo
index 6c4d180..ff2afe7 100644
--- a/moo/kernel/Socket.moo
+++ b/moo/kernel/Socket.moo
@@ -9,6 +9,7 @@ class(#byte) IPAddress(Object)
 {
 }
 
+### TODO: extend the compiler
 ###class(#byte(4)) IP4Address(IPAddress) -> new basicNew always create 4 bytes. size to new: or basicNew: is ignored.
 ###class(#byte(16)) IP6Address(IPAddress)
 
@@ -52,7 +53,7 @@ class(#byte) IP4Address(IPAddress)
 
 			if (c >= $0 and: [c <= $9])
 			{
-				acc := acc * 10 + (c - $0) asInteger.
+				acc := acc * 10 + (c asInteger - $0 asInteger).
 				if (acc > 255) { Exception signal: ('invalid IPv4 address B ' & str). }.
 				digits := digits + 1.
 			}
@@ -253,12 +254,13 @@ class MyObject(Object)
 		| s conact inact outact |
 
 
-s := IP4Address fromString: '192.168.1.1'.
-s dump.
-s := IP6Address new.
-s dump.
-s := IP4SocketAddress new.
+s := IP4Address fromString: '192.168.123.232'.
 s dump.
+s basicSize dump.
+##s := IP6Address new.
+##s dump.
+##s := IP4SocketAddress new.
+##s dump.
 thisProcess terminate.
 		inact := [:sck :state |
 			| data n |
diff --git a/moo/lib/pf-basic.c b/moo/lib/pf-basic.c
index 3920fb6..2fc3e74 100644
--- a/moo/lib/pf-basic.c
+++ b/moo/lib/pf-basic.c
@@ -260,11 +260,13 @@ moo_pfrc_t moo_pf_basic_size (moo_t* moo, moo_ooi_t nargs)
 
 	if (!MOO_OOP_IS_POINTER(rcv))
 	{
+		/* a non-pointer object has the size of 0. 
+		 * such an object doesn't consume object memory space except an OOP word */
 		sz = MOO_SMOOI_TO_OOP(0);
 	}
 	else
 	{
-		sz = moo_oowtoint (moo, MOO_OBJ_GET_SIZE(rcv));
+		sz = moo_oowtoint(moo, MOO_OBJ_GET_SIZE(rcv));
 		if (!sz) return MOO_PF_FAILURE;
 	}
 
@@ -377,19 +379,17 @@ moo_pfrc_t moo_pf_basic_at_put (moo_t* moo, moo_ooi_t nargs)
 		case MOO_OBJ_TYPE_BYTE:
 			if (!MOO_OOP_IS_SMOOI(val))
 			{
-				/* the value is not a character */
-				moo_seterrnum (moo, MOO_EINVAL);
+				moo_seterrbfmt (moo, MOO_EINVAL, "value not a byte - %O", val);
 				return MOO_PF_FAILURE;
 			}
 /* TOOD: must I check the range of the value? */
-			((moo_oop_char_t)rcv)->slot[idx] = MOO_OOP_TO_SMOOI(val);
+			((moo_oop_byte_t)rcv)->slot[idx] = MOO_OOP_TO_SMOOI(val);
 			break;
 
 		case MOO_OBJ_TYPE_CHAR:
 			if (!MOO_OOP_IS_CHAR(val))
 			{
-				/* the value is not a character */
-				moo_seterrnum (moo, MOO_EINVAL);
+				moo_seterrbfmt (moo, MOO_EINVAL, "value not a character - %O", val);
 				return MOO_PF_FAILURE;
 			}
 			((moo_oop_char_t)rcv)->slot[idx] = MOO_OOP_TO_CHAR(val);
@@ -399,7 +399,7 @@ moo_pfrc_t moo_pf_basic_at_put (moo_t* moo, moo_ooi_t nargs)
 			if (!MOO_OOP_IS_SMOOI(val))
 			{
 				/* the value is not a number */
-				moo_seterrnum (moo, MOO_EINVAL);
+				moo_seterrbfmt (moo, MOO_EINVAL, "value not a half-word integer - %O", val);
 				return MOO_PF_FAILURE;
 			}
 
@@ -414,7 +414,7 @@ moo_pfrc_t moo_pf_basic_at_put (moo_t* moo, moo_ooi_t nargs)
 			if (moo_inttooow (moo, val, &w) <= 0)
 			{
 				/* the value is not a number, out of range, or negative */
-				moo_seterrnum (moo, MOO_EINVAL);
+				moo_seterrbfmt (moo, MOO_EINVAL, "value not a word integer - %O", val);
 				return MOO_PF_FAILURE;
 			}
 			((moo_oop_word_t)rcv)->slot[idx] = w;