Codes in binary system BCD codes: for decimal digit; Gray code: for numbers in binary system; AsCII code: for characters; Key point Use n bits, we can make 2n different words; To make n code-words you must use log, n bitsCodes in binary system BCD codes: for decimal digit; Gray code: for numbers in binary system; ASCII code: for characters; Key point : Use n bits, we can make 2n different words; To make n code-words, you must use bits. log 2 n