How can I tell which revision of a chip I am using and what do the characters on the top of the MCU package mean?
The characters on the top of the MCU package will tell the revision of the chip and the date that the chip was built.
Date and Trace Codes
On standard packages, the date and trace code has the format: YYWW RTTTTT
Example Package Markings
The examples below show part markings for a theoretical C8051F123 or CP1234 device: