Hello World in Morse Code

"Hello, world" became the standard first program after it appeared in Brian Kernighan's 1972 tutorial for the language B, and again in The C Programming Language in 1978. Since then, printing it has been how programmers check that a new language, compiler or device is working at all.

That is exactly why it keeps turning up in Morse. It is the phrase people reach for when they build a Morse encoder as a learning exercise, wire up a buzzer to a microcontroller, or test that an LED can blink accurately enough to be read. If the buzzer produces .... . .-.. .-.. --- / .-- --- .-. .-.. -.. at the right speed, the whole chain works.

There is a pleasing symmetry to it: the greeting that verifies a new machine, written in the code that opened the first electrical communication network.

Sending this from a microcontroller is a common first project, and the part that catches people out is never the letters — it is the gaps. The 1-3-3-7 rule means five different delays: one unit for a dot, three for a dash, one between the parts of a letter, three between letters and seven between the two words.

Get the letter gaps wrong and the message still blinks convincingly but decodes to nonsense. Run WORLD together without the three-unit separations and a reader gets a completely different sequence of characters.

The full timing table, with every gap converted to milliseconds for any speed, is on the Morse code timing page. Twenty words per minute is a good target: fast enough to sound real, slow enough to check by ear against the audio here.

• HELLO in Morse code
• Morse code timing and WPM
• Hear any message in Morse code