There's a well-documented reason for the placement of (nearly) every single character in ASCII. Unfortunately, not all of the reasons are still very compelling. In fact, a distressingly large number of them have to do with the various techniques for encoding bytes on punch cards.

For the curious, I recommend the book "Coded Character Sets: History and Development" by Charles E. Mackenzie. It's an older book, and so it's about the pre-Unicode, US-centric codes. Also, most of the pages focus on the many variants of EBCDIC rather than the stabler ASCII standard. But I guarantee that it will give you a lot of historical perspective.

Holy $h!7 - That book is 650 pages. That is a lot of history.

Amazon's information is incorrect. According to WorldCat and Google Books, the book is 513 pages, not 650. Also, its copyright date should be 1980, not 1979.

Since this is such a burning question — my copy is ©1980 and ends at page 513. I am now desperate to see the 137 pages of shocking censored material from the legendary 1979 edition.

Surely EBCDIC is what you're referring to?

Turns out there's a reason for their placement:

- "The digits 0–9 were arranged so they correspond to values in binary prefixed with 011, making conversion with binary-coded decimal straightforward."

- "The letter "A" was placed in position 0x41 to match the draft of the corresponding British standard."

(Source: wikipedia.)

Another interesting bitwise trick: flip bit 5 to swap the case of an alphabetic letter.

The 1963 standard (linked from the article, and below[1]) does a reasonable job of describing the design rationale in the appendices.

“B4.2 Base 12 Numeric Digits. For those applications requiring use of the sterling monetary system or duodecimal arithmetic, the digits 10 and 11 can replace the two graphics immediately following the digit 9.”

[1] http://www.wps.com/projects/codes/X3.4-1963/index.html

For anyone confused about pre-decimal English currency (http://gwydir.demon.co.uk/jo/units/money.htm)

4 farthings = 1 penny

48 farthings = 1 shilling

960 farthings = £1

There were farthings, half-pennies, pennies, threepences, sixpences, shillings, florins, and half-crowns.

I guess we're lucky in only having to fiddle around with dates in awkward formats.

> I guess we're lucky in only having to fiddle around with dates in awkward formats.

And that thing that isn't the metric system.

To be fair, traditionally there weren't a lot of events where you needed to figure out the number of farthings in a pound. I also read somewhere that loans were generally set at 5% (one shilling interest per pound loaned) because working out any other number was a pain in the neck. No idea of the date or veracity of that little nugget though.

I always thought the guinea was particularly funny, given that it doesn't really add much in the way of demarcation.