How do you identify an integrated circuit from serial numbers?

Semiconductor integrated circuits usually don't have serial numbers on them with the exception of VLSIC's (very large scale integrated circuits) or microprocessors. Semiconductors almost universally have two identifiers marked on them. One is a code the manufacturer uses to identify the lot (or batch) that the semiconductor came from. The other number is an identifier that can almost certainly be used to find out about the semiconductor, discover its characteristics and what it does. That identification number can be used to cross-reference the device, and there are a number of online resources that will provide cross reference information and even device characteristics without cost save the time it takes to access the data and read it.