ASCII codes - interactive ascii code table   

History of ASCII Codes

The ASCII code, or the American Standard Code for International Exchange, seems as though it has been around forever. We tend to take it for granted that we are able to communicate using letters on the Internet, rather than having everything be a system of numbers that only computers on the same system could interpret. Now, computers from any company can communicate with one another and have it be easily understood.

A Representation of the Situation
During the beginning of the 1960s, there was no standard for communication, which meant that all computer manufacturers were creating methods of communication that best matched their individual products. This resulted in a huge number of problems. The first was that there was no way for one computer from one company to interpret information from another computer because the information would all be presented and interpreted in different ways. This was a severe barrier to actually making the computer useful.

The situation arose because computers really only communicate in numbers. Every computer manufacturer had its own method of using numbers to convey letters and symbols that the other computer manufacturers did not use. At the time, there were 60 different ways that computers could interpret the string of numbers that were meant to represent alpha-numeric characters and symbols. IBM had 9 of these different methods alone. This resulted in mass confusion.

1961: a Solution to the Confusion Begins to Develop
The computers that IBM used were not even able to communicate with one another, let alone the rest of the computers that all of the other manufacturers were creating. One of the leaders of IBM, Bob Bemer, recognized that this was a huge problem. In the May of 1961, Bob Bemer went to the American National Standards Institute (ANSI) with a proposal. He suggested that a common code be used by all computers so that they could all communicate with one another, offering his own ideas as part of the code itself. A committee was immediately created to further develop this proposal. It was called X3.4 and was made up of most of the leading manufacturers of computers in the 1960s and chaired by John Auwaerter, the vice president of the Teletype Corporation.

1963: the ASCII is Created
It was a 2 year process in order for X3.4 to actually come to an agreement about the ASCII codes. The discussions were plagued by self-interest, with each computer manufacturer wanting the code to be created so that it exactly matched up with the computers that his company created. Eventually Bob Bemer and John Auwaerter met outside of the discussions and hammered out the ASCII.

1964: the First Attempt
IBM worked on their Operating System/360 to make it work with ASCII, but when the operating system itself was ready, the punch cards that would be necessary for ASCII to be used were not. Instead, attempts were made to for the OS/360 to switch from ASCII to an extension of the original punch and code system, but they were not particularly successful.

1964-1981: Progress Stalls
When IBM's efforts failed, most of the other computer manufacturers lost interest in using the code. The only computer that actually utilized the ASCII codes was the UNIVAC 150.

1981: ASCII Returns
In 1981, IBM finally creates its first PC and utilizes ASCII so that the data could be interpreted easily. This is the official first start of the ASCII being used by computers. After this computer was created, all others created afterwards used ASCII, nationwide as well as internationally. ASCII is still used by every computer today, except for the Windows computers that are currently using Unicode.

Gradually ASCII evolved to include both capital and lowercase letters that are standards in the English alphabet, numbers, and common punctuation symbols, as well as more specific characters such as letters with accents and other symbols. Since 1963, at least 150 languages have been defined by ASCII, which is still in widespread use today. Without ASCII, we would not have been able to make the huge strides in information sharing and communication that we have enjoyed.

ASCII Code Table

ASCII stands for American Standard Code for Information Interchange. Having a standardized code is very important because computers are only able to adequately understand numbers. In order to convey everything that needs to be conveyed through a computer, a number-based code needed to be created that could be used to represent non-numeric characters, such as "b" or ";".

Originally the ASCII code only had numbers and capital letters, but in 1967 lowercase letters and a few control characters were added to the system. It was not until 1981, when IBM started to augment the code, that we were able to access the full 255 characters that we are today. The original set of ASCII code characters were characters 1-127. The characters ranging from 128-255 added many different symbols and made it so languages that relied on accents, such as Spanish, to also be written using the code.

How to Use ASCII Code:

For Windows:

1. Press the Alt key on the keyboard.
2. While holding the Alt key, type the number of the symbol that is desired. For example, an "e" with an accent (é) has the code number 130. To get this character, simply hold Alt and type 130.
3. Let go of the Alt key once the character has been accessed.

For Linux:

1. Press Control, Shift, and "u", all at the same time.
2. While holding all three of the keys mentioned above, type the number of the symbol that is desired. The same number that works for Windows will also work for Linux because the code is standardized.
3. Let go of Control, Shift, and "u".

Why is ASCII Important?

Whenever a person uses a computer to write or read a file, that file is stored as a series of number, rather than the series of numbers, letters, and other characters that it appears to be. In order for people to be able to use computers to communicate with one another, it is critical that there is a reliable way of interpreting the numeric data. This means that all computers need to be able to analyze the data and produce the same results every single time. The ASCII provides a way to map all of the data so that every character in the English language is interpreted the same way every single time. An ASCII code table provides a list of all of the symbols and their numeric representation.

Types of ASCII Codes

Control Characters
The first 32 codes (numbers 0-31) are specifically reserved for functions, rather than other symbols. They don't actually represent any information that is able to be printed, but rather consist of data that can be used to control other devices, such as the printer. These characters include:

• ASCII code 00 = NULL ( Null character)
• ASCII code 01 = SOH (Start of Header)
• ASCII code 02 = STX (Start of Text)
• ASCII code 03 = ETX (End of Text, hearts card suit)
• ASCII code 04 = EOT (End of Transmission, diamonds card suit)
• ASCII code 05 = ENQ (Enquiry, clubs card suit)
• ASCII code 06 = ACK (Acknowledgement, spade card suit)
• ASCII code 07 = BEL (Bell)
• ASCII code 08 = BS (Backspace)
• ASCII code 09 = HT (Horizontal Tab)
• ASCII code 10 = LF (Line feed)
• ASCII code 11 = VT (Vertical Tab, male symbol, symbol for Mars)
• ASCII code 12 = FF (Form feed, female symbol, symbol for Venus)
• ASCII code 13 = CR (Carriage return)
• ASCII code 14 = SO (Shift Out)
• ASCII code 15 = SI (Shift In)
• ASCII code 16 = DLE (Data link escape)
• ASCII code 17 = DC1 (Device control 1)
• ASCII code 18 = DC2 (Device control 2)
• ASCII code 19 = DC3 (Device control 3)
• ASCII code 20 = DC4 (Device control 4)
• ASCII code 21 = NAK (NAK Negative-acknowledge)
• ASCII code 22 = SYN (Synchronous idle)
• ASCII code 23 = ETB (End of trans. block)
• ASCII code 24 = CAN (Cancel)
• ASCII code 25 = EM (End of medium)
• ASCII code 26 = SUB (Substitute)
• ASCII code 27 = ESC (Escape )
• ASCII code 28 = FS (File separator)
• ASCII code 29 = GS (Group separator)
• ASCII code 30 = RS (Record separator)
• ASCII code 31 = US (Unit separator)

Printable Characters
Printable characters are the characters that make up the rest of the ASCII code table (numbers 32-255). They include uppercase letters, lowercase letters, punctuation marks, letters with accents, and symbols.

7 Bit and 8 Bit Codes
ASCII codes come in both 7-bits and 8-bit variations. 7-bit coding was the most popular until 2008, when UTF-8, or 8-bit codes took over.