I have large numbers of records store in 24C256,4 bytes for 1 record. The record store in EEPRom is in sequence,and I want to find a record matched data from them. I now write a subfunction like following: First,I read record 1 form EEPRom,verify it and find if it is match my data. If match, return "1"(the record NO.);If no,I read record 2 ... and so on. If the last record is reached and it is still not the record I wanted,The function will return "0". Is this called Compare In Sequence Arithmetic? Routine will be very slowly when the matched record is in the back of EEPRom. The Dichotomy Arithmetic and Cut In Block Arithmetic cann't be use because of the record stored in EEPRom is random. Can you tell me a good arithmetic? Thank you.