tymshft

There is nothing new under the sun…turn, turn, turn

ASCII and get the ANSI when U ni(d) code – why EBCDIC is like it is

I was saving a text file one day, and noticed that I could save that file in various formats, including several Unicode formats and an ANSI format.

As I was looking at my options, an old acronym suddenly popped into my head.

EBCDIC.

This is probably the first time that I’ve thought about EBCDIC in this millennium, so I had to research it to remember what it was. I ended up at Dynamoo.

ASCII is the American Standard Code for Information Interchange, also known as ANSI X3.4. There are many variants of this standard, typically to allow different code pages for language encoding, but they all basically follow the same format. ASCII is quite elegant in the way it represents characters….ASCII is essentially a 7-bit code which allows the 8th most significant bit (MSB) to be used for error checking, however most modern computer systems tend to use ASCII values of 128 and above for extended character sets.

Although not mentioned in this particular write-up, Unicode is essentially an extension of ASCII.

But there is another character standard floating around.

EBCDIC (Extended Binary Coded Decimal Interchange Code) is a character encoding set used by IBM mainframes. Unlike virtually every computer system in the world which uses a variant of ASCII, IBM mainframes and midrange systems such as the AS/400 tend to use a wholly incompatible character set….

Before you say that this is irrelevant, consider that there are still a number of AS/400 systems – whoops, I mean IBM iSeries systems – out there, used in places such as colleges.

Why am I writing about this in tymshft? Because of the origins of EBCDIC.

IBM mainframes and midrange systems such as the AS/400 tend to use a wholly incompatible character set primarily designed for ease of use on punched cards.

So even though no one uses punched cards for computer input any more, there are certain systems that are the way they are because of punched cards.

Advertisements

Single Post Navigation

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: