Morse..

Spent 3 hours a day, 5 days a week for 2 years bashing a morse key just like this one at Radio College (for Merchant Navy entry)..
It's now irreversibly imprinted in my grey cell, like a second language..!
Note, it isn't just the 26 alphabet characters, there's also the numbers 0 to 9, about 12 punctuation characters ( / ) - + ? ' . etc. and 5 accented letters (as in French, Spanish & German languages) all told around 53 characters...

(Today's really useless fact....).