Why do you have to use Morse code on a telegraph?

Answer 1

Because a telegraph does not have the facility to transmit words but only noise, it's necessary to convert that noise into something that can be understood. One method is to use Morse Code. But if somebody could come up with some other code then you could use that.

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Eventually the telegraph companies developed a machine called a teletype with a keyboard and early type of electromagnetic printer. It could be connected to standard telegraph lines and then instead of having to use Morse code the operator could type the message in words on the keyboard of his teletype and the printer on the distant teletype would print the message in words.

The first teletypes used a 6 bit code called Baudot, but in the early 1960s improved teletypes using a 7 bit code called ASCII replaced them.

ASCII was also soon adopted by most computer manufacturers as the character code their computers used (before this computer manufactures tended to use proprietary character codes making transferring data between different manufacturer's computers difficult).