American Code For Information Interchange (ASCII) Overview

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Updated March 05, 2024
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What Is the American Code for Information Interchange (ASCII)?

The American Code for Information Interchange, commonly called ASCII, is a computer language for text that became the standard for transmitting information between computers in 1963.

The ASCII system translates alphanumeric characters and symbols into a computer-readable code. The original ASCII was English-only. There are now two types of ASCII codes; the standard code that uses a seven-bit encoding system, and an extended code that uses an eight-bit system.

In internet communications, ASCII has gradually been superseded by the Unicode standard, which can be used with any language and is compatible with ASCII. However, ASCII is still used for entering text on personal computers and electronic devices.

It is pronounced ASK-y.

Key Takeaways

  • The American Code for Information Interchange, or ASCII, is a character encoding format designed for use in transmitting text between computers.
  • ASCII originally contained only 128 English-language letters and symbols but was later expanded to include additional characters, including those used in other languages.
  • ASCII continues to exist but has been largely replaced by Unicode, which can be used to encode any language.

Understanding the American Code for Information Interchange (ASCII)

The earliest iteration of ASCII can be found in a telegraphic code used by Bell data services to deliver messages to teleprinters.

ASCII was the first major character encoding system for data processing and was adopted as the standard for computing in 1963 and in 1968 it was mandated that all U.S. government computers be ASCII compatible. It was used for many years in the order-entry computer systems used by Wall Street traders and brokers.

It has been gradually replaced as the standard for the internet by the Unicode Worldwide Character Standard (Unicode). However, since the first 128 characters of Unicode are the same as those in ASCII, the two systems can be said to co-exist.

You can enter an ASCII symbol into a document using any Windows-compatible computer by holding down the ALT key while typing the character code number. For example, holding the ALT key while typing 156 will give you £, the British pound sign.

What's In ASCII

Before ASCII was adopted as a standard, every computer maker used its own code, and some companies used more than one for different products. Computers were unable to communicate with one another.

Although ASCII was adopted as the standard by the American National Standards in 1963, it was not fully implemented even in the U.S. until 1968, when President Lyndon B. Johnson mandated its adoption by the federal government in order to ensure that government computers and telecommunications industry computers could communicate with each other.

ASCII originally contained 128 alphabetical characters, numbers, and symbols and was based on the English language. Extended forms were added through the 1970s to accommodate other languages.

Soon, various versions of ASCII were in use. It eventually included 256 characters. This version was released in 1981 and is known as Extended ASCII.

Today, Windows computer users can enter ASCII or Unicode symbols such as a copyright symbol into documents by pressing the alt key and entering the character code on the numeric keypad with the NUM lock key on.

What Is ASCII?

The American Standard Code for Information Interchange, or ASCII, is a character encoding format for the electronic transmission of text. Every character is represented by a unique number. The first version of ASCII contained only 128 characters, representing the letters of the alphabet, capitalized and lower-case, plus a number of commonly-used symbols such as the comma.

Later versions extended ASCII to 256 characters, including additional symbols such as the British pound symbol (£)and the upside-down question mark used in Spanish text (¿).

What Are the ASCII Characters?

In the Extended ASCII table, character codes 0 through 31 are control codes such as start of text and backspace.

Character codes 32 through 127 are mostly letters of the alphabet (capitalized and lower case) and symbols like the asterisk and the dollar sign.

Character codes 128 through 255 comes in several versions, each of them reflecting additions to the original English-only ASCII such as an inverted exclamation mark, the yen sign, and the Georgian comma.

What Is ASCII vs. Unicode?

Unicode could be seen as a universal version of ASCII.

ASCII is, after all, the American Code for Information Interchange, and its first iteration included the English-language alphabet and symbols used in the language. Later versions included symbols used in many other languages.

Unicode, on the other hand, starts with the same 128 symbols used in ASCII but current versions contain 149,186 characters.

Article Sources
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  1. Computer History Museum. "Timeline of Computer History."

  2. Jeremy Norman's Historyofinformation.com. "ASCII (American Standard Code for Information Exchange) Is Promulgated."

  3. ASCII-Code.com. "ASCII 1963."

  4. Britannica. "ASCII."

  5. Spiceworks. "ASCII vs. Unicode: 4 Key Differences You Must Know."

  6. Britannica. "ASCII."

  7. ASCII-Code.com. "Timeline of ASCII History."

  8. ASCII-Code.com. "ASCII Table."

  9. ASCII-Code.com. "ASCII Table."

  10. Unicode.org. "Basic Questions."

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