--- a/ExternalAddress.st	Tue Nov 15 16:37:32 2016 +0100
+++ b/ExternalAddress.st	Tue Nov 15 16:43:29 2016 +0100
@@ -105,7 +105,29 @@
 !ExternalAddress class methodsFor:'instance creation'!
 
 newAddress:addr
+    "return a new externalAddress (pointer), pointing to addr."
+
     ^ self new setAddress:addr
+
+    "Modified (comment): / 15-11-2016 / 11:57:34 / cg"
+!
+
+newAddressFromBytes:bytesContainingAddress
+    "return a new externalAddress (pointer), pointing to the addr contained in the argument.
+     The argument must be a byteArray-like object, whose first pointerSize bytes are extracted"
+
+    ^ (bytesContainingAddress pointerAt:1)
+
+    "
+     |bytes ptr|
+
+     bytes := ByteArray new:(ExternalAddress pointerSize).
+     bytes pointerAt:1 put:16r12345678.
+     ptr := ExternalAddress newAddressFromBytes:bytes.
+     self assert:(ptr address = 16r12345678).
+    "
+
+    "Created: / 15-11-2016 / 12:53:21 / cg"
 ! !
 
 !ExternalAddress class methodsFor:'Compatibility-V''Age'!
@@ -126,18 +148,21 @@
 
 isBuiltInClass
     "return true if this class is known by the run-time-system.
-     Here, true is returned."
+     Here, true is returned (but not for subclasses)."
 
     ^ self == ExternalAddress
 
-    "Modified: / 11.6.1998 / 17:12:40 / cg"
+    "Modified: / 11-06-1998 / 17:12:40 / cg"
+    "Modified (comment): / 15-11-2016 / 11:56:55 / cg"
 !
 
 pointerSize
     "answer the size in bytes of a pointer.
      Notice: this is inlined by the compiler(s) as a constant,
-     therefore, a query like 'ExternalAddress pointerSize == 8'
-     costs nothing; it is compiled in as a constant."
+     therefore, queries like 
+        'ExternalAddress pointerSize == 8'
+     cost nothing; they are compiled in as a constant 
+     (and even conditionals are eliminated)."
 
 %{ /* NOCONTEXT */
     RETURN(__mkSmallInteger(sizeof(void *)));
@@ -146,8 +171,30 @@
     "
      self pointerSize
     "
+
+    "Modified (comment): / 15-11-2016 / 11:56:38 / cg"
+!
+
+sizeOfPointer
+    "answer the size in bytes of a pointer.
+     Notice: this is inlined by the compiler(s) as a constant,
+     therefore, queries like 
+        'ExternalAddress pointerSize == 8'
+     cost nothing; they are compiled in as a constant 
+     (and even conditionals are eliminated)."
+
+%{ /* NOCONTEXT */
+    RETURN(__mkSmallInteger(sizeof(void *)));
+%}.
+
+    "
+     self sizeOfPointer
+    "
+
+    "Created: / 15-11-2016 / 11:40:52 / cg"
 ! !
 
+
 !ExternalAddress methodsFor:'Compatibility-Squeak'!
 
 beNull
@@ -308,9 +355,14 @@
         addr = __intVal(anInteger);
     } else {
         addr = __unsignedLongIntVal(anInteger);
+        if (addr == 0) {
+            console_printf("invalid address argument in ExternalAddress>>setAddress\n");
+        }
     }
     __INST(address_) = (OBJ)addr;
 %}
+
+    "Modified: / 15-11-2016 / 11:59:24 / cg"
 !
 
 setAddressFromBytes:aByteArray