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What is ASCII: A Guide for Beginners

Christina Kopecky - June 18, 2022


The American Standard Code for Information Interchange (ASCII) is a standard that takes English characters, numbers, punctuation symbols, and other special characters, and assigns them somewhere in the 255 slots available in the 8-bits of code that were available to older computers.

Understanding ASCII will help your understanding of what coding is and how it works. This article takes a quick look at the history of ASCII, and describes its importance.

Why was ASCII created?

ASCII’s creation came out of the use of telegraph machines. Computers had a number of different ways to create characters on their systems prior to the 1960s. As computer networking grew, it became clear that there needed to be a consistent way to represent the different characters so that communication could happen between machines.

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The American National Standards Institute, a non-profit group, received a request from IBM engineer Bob Bemer to create an organization able to generate a standard so that there could be a single code for computer communication. This new committee, under the leadership of an engineer from the TeleType Corporation, took two years to reach an amenable solution to the problem.

This solution came to be known as ASCII.

ASCII Codes

The original ASCII character set was 128 characters and assigned to slots from 0 to 127. The initial delineation between the types of characters and where they were assigned was whether or not the character created a command or not.

Control Characters

The control characters in the ASCII format were non-printable characters. Instead, they indicated some sort of command or pointer. Examples include \e (“escape”), \? (“delete”), and \0 (“null character”).

These are characters read by the operating system. The symbols given as examples here are only listed to be readable to humans — they are not what is read by the computer.

These control characters take up the first 32 slots (0 to 31) of 8-bit code.

Printable Characters

The rest of the slots, from 32 to 127, are printable characters that we can read. These include punctuation marks, spacebar space, capital letters, lowercase letters, numbers, and special characters.

SP!”#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

The printable ASCII characters, from 32 to 127. The very first character, a space, is indicated by SP.

Extended ASCII

The Extended ASCII is the newest portion of the ASCII standard. The extended standard itself isn’t as clear cut as the original There are variations of the standard but the overall meaning remains the same: its purpose was to be more inclusive of non-English-speaking countries.

The Extended ASCII table lists currency symbols, letters in other languages, and accent symbols.

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Conclusion

ASCII was created to create a single source of truth for communication among computers in the 20th century. Since its inception, the table has grown to include Extended ASCII symbols that use non-US symbols, accents, letters, and symbols.

A new standard has also grown out of ASCII to include even more characters called Unicode.

It’s always good to know where we have come from — ASCII was remarkable for its time because it made it possible for computers to talk to one another. ASCII continues to be used to this day alongside newer standards.

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Christina Kopecky

About the author: Christina is an experienced technical writer, covering topics as diverse as Java, SQL, Python, and web development. She earned her Master of Music in flute performance from the University of Kansas and a bachelor's degree in music with minors in French and mass communication from Southeast Missouri State. Prior to joining the Career Karma team in June 2020, Christina was a teaching assistant, team lead, and section lead at Lambda School, where she led student groups, performed code and project reviews, and debugged problems for students. Christina's technical content is featured frequently in publications like Codecademy, Repl.it, and Educative.

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