The first draft of ASCII was made by Bob Bemer, a engineer from IBM, to replace the various teleprinter codes used in the 1950s. It was submitted to the American Standards Association (ASA), which later became the American National Standards Institute (ANSI), in 1961. ASCII was based on the earlier teleprinter codes, but added some new characters, such as the backspace and delete characters. It also standardized the use of control characters, such as carriage return and line feed.
The first version of ASCII was published in 1963 as ASA X3.4-1963, and was used by the Teletype Model 33. It had the uppercase letters, digits, and control characters, which were used for controlling mechanical functions of teleprinters. There was a brief debate over whether the remaining 28 codes should be used for lowercase letters or special characters, but in May 1963 the CCITT Working Party on the New Telegraph Alphabet recommended the addition of lowercase letters. They were added such that they were a single bit different from their uppercase counterparts, which made it easier to convert between the two. They were added in the 1967 revision, ASCII-1967.