ASCII Encoding Guide

ASCIIEncodingASCII is extremely important to all of us. As computers were developed in the 1950s and ’60s, it became THE way to move data between two dissimilar systems. All computers could understand ASCII, and it became the base character set for every platform from the smallest microcontroller to the largest mainframe.

Bryan Innes from recently pointed me to an article on his site,, which gives more information on ASCII than you’ll ever want to know. Despite that, it is really interesting. I learned some new things about ASCII:

  • There is a lot of history to ASCII – Bell Labs had a hand in it as did IBM, who started the move to that type of encoding in the old punched card days
  • 7-bit encoding (odd number, isn’t it?) exists because memory was so precious 60 years ago that saving one single bit was really important
  • The Unicode encoding scheme was developed to support languages other than English. For a long time I wondered what all this UTF stuff was until finally going and looking it up. UTF-8, it turns out, is the version that is compatible with the old ASCII that geeks like me know and love. UTF-16 and UTF-32 are for languages with really big character sets.

It’s a fascinating article from Bryan that not only describes the history of ASCII encoding but also lists a set of resources that may be of use to you. I have a bit of this in my Industrial Ethernet Book, but Bryan has done a much better job than I of going into the details of ASCII.

And, of course, he includes some ASCII art. For those of you who weren’t around in the 1970s and 1980s, people were always trying to outdo each other by creating pictures from characters in the ASCII character set.

You have to remember that we had dot matrix printers in those days and what passed for fun was watching the head slowly move left to right and right to left as it rendered one of these images. There were some guys (and they were only guys) that were quite good at this and able to generate some really fine art as well as the occasional picture of a topless or naked girl.

Bryan’s article is quite interesting. It’s a distraction from my usual discussion of ProfiNet IO, EtherNet/IP, Modbus RTU and the rest, but I think you’ll enjoy it.
Here’s the link again:

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