small cleanup in BASIC, improved cartridge compatibility

c64/basic/,stubs/e38b.error.s

@@ -0,0 +1,17 @@
+#if ROM_LAYOUT_STD || (ROM_LAYOUT_M65 && SEGMENT_BASIC_0)
+
+//
+// Official BASIC routine, described in:
+//
+// - [RG64] C64 Programmers Reference Guide   - XXX
+// - [CM64] Computes Mapping the Commodore 64 - page 69, XXX
+//
+// CPU registers that has to be preserved (see [RG64]): XXX
+//
+
+
+ERROR:
+	STUB_IMPLEMENTATION()
+
+
+#endif // ROM layout