The first code only reads from the EM-4100 tag (read only tag): http://www.parallax.com/Store/Accessories/Hardware/tabid/162/ProductID/115/List/1/Default.aspx?SortField=ProductName,ProductName
not sure if it reads written data.
what I have is the EM4x50 tag.
The difference between these 2 tags is that the EM-4100 (read only) contains a unique 10 digit ID, while the EM4x50 (read and write) tag contains a unique read-only serial number (one of 2^32, or 4,294,967,296 possible combinations) and 116 bytes of user data area stored in a non-volatile EEPROM (Electrically Erasable Read Only Memory).