In a previous Tech Talk Tuesday post, I mentioned that I would try to focus on concepts for my posts, and this week, I plan to deliver.
The American Standard Code for Information Interchange (ASCII) is a character encoding set created in the 1960s by the American Standards Association (ASA), which is now the American National Standards Institute (ANSI). ASCII was one of the first character encoding sets to be created and used for computers, and quickly gained popularity when President Lyndon B. Johnson mandated that all federal government computers support ASCII.
ASCII, and almost any other character encoding scheme, works by assigning numbers to characters. Computers can easily store numbers in binary format, so when a character encoding scheme is chosen for display, those numbers are shown as human-readable characters. In this case, ASCII works specifically for American English.
Example of an ASCII-encoded text file
To read more about ASCII and view the full ASCII table, see the tutorial below:
ASCII
June 13, 2016
A brief history of how ASCII came to be, how it's useful to computers, and some helpful tables to convert numbers to characters.
While there are plenty of ASCII tables on the 'net, I figured I could be slightly more useful by offering an image version of the table to do with as you please.
You can download black and white versions of the image in this ASCII table pack:
With these, you are welcome to print them out, frame them above your monitor, print them on a coffee mug to show your love of American computing history or, for a more useful approach, have it printed onto a custom mouse pad.
Final fun fact of the day: ASCII was the most popular character encoding for web pages until December 2007, when it was surpassed by UTF-8 which, interestingly enough, is backwards compatible with ASCII.
As a foreigner of European descent and also former i18n engineer, I'd like to point out that when ASCII was popular on the web, it also included the "extended" part of the character set. This resulted in what is called ISO 8859. Without this, it would've been difficult for web browsers to display things like "Jag älskar smörgåstårta," and "¿Dónde está el baño?"
There was also a limited 7 bit version and since it was one bit shorter, it had only half as many characters. It was often referred to as "half-ascii".
But the full ASCII character set is already only 7 bits?
Screw ASCII! Mac Roman 4 life!!! Or 16 bit Unicode... that’s good too...
And every computer book, whether it was relevant or not, always seemed to have an ASCII table at the back.
What confuses novice C programmers is that the ASCII code was designed so that c-'0' would get you the numeric value of the character.
Back in High School, the DOS/Win 3.1 days, my ALT keystroke ASCII directories were the bane of many a computer science teacher. Difficult to delete and access. Such as the §t܃ƒ (stuff) directory. (ALT + 0167), t, (ALT + 0220), (ALT + 0131), (ALT + 0131).
"Delete" was also known as "rub out". It was useful when there was a typo on punched paper tape. Since it was all holes punched (all 1s in binary), punching it on top of any character would replace it with "delete". It was easy enough to make paper tape readers just ignore any such instances, avoiding the need to repunch a whole tape if one character was mistyped.