What is a CRC?
ROMs can be identified using a special checksum algorithm called CRC32 (a 32 bit cyclic redundancy check). A perfect checksum algorithm applied to billions of different files should not have a tendency to generate a particular checksum more than any other. In other words, the chance of two different files having the same CRC should only be about 1 in 4 billion (2^32=largest 32-bit number). CRC32 is the most effective checksum algorithm in this respect. Amongst other things, CRC32 is used by WinZIP to validate the integrity of ZIP archives and for hardware error detection in some types of network.
