MorseDojo

Copying on the mill

Radio operators in the Royal and US Navies did not write morse down — they typed it, straight onto a typewriter called a mill. No backspace, nothing marked until the message ended, and a group count that told you on your own whether you had all of it. This is that, in a browser.

Pick a signal. You will not be shown what it says.

What was a mill, and why copy this way?

The machine

A mill was a typewriter, and radio operators copied morse straight onto one. It was not an ordinary office machine: it typed capitals only, because there is no shift in morse and nothing to shift for, and it carried a slashed zero so nobody could mistake it for the letter O. Paper went in several plies thick with carbon between, so one operator's copy came off the machine as the four or five copies the message actually needed.

Why type it rather than write it

A message written down by hand had to be typed up afterwards anyway, before it could go anywhere. Copying directly onto the mill removed a whole step and a whole opportunity to introduce mistakes — and when the traffic is steady and the volume is high, that step is the difference between keeping up and falling behind. Trainees learned to touch-type first, then learned to do it with morse coming at them.

Why there is no going back

You cannot backspace a mechanical typewriter through five plies of carbon paper, and even if you could, you should not: the message does not stop while you fix a letter. Stop to correct one character and you have lost the next five. So the discipline was to leave the mistake and keep going — a rough copy of the whole message beats a beautiful copy of the first half of it. That is why backspace does nothing here. It is the mode, not a missing feature.

Copying behind

Good operators do not type the character they are hearing. They run two, three, sometimes half a dozen characters behind the sending, holding the rest in their head — which sounds impossible and turns out to be the only way it works at speed. Chasing each character as it arrives means every hesitation costs you the next one. The counter on the paper shows how far back you are sitting; further back is not a fault.

The group count

Formal traffic carries its own count — GR 11 means eleven groups of text are on the way. It travels with the message for one reason: so the receiving operator can count what he has written down and know, on his own, whether he got all of it. Counts agree and the message is good. Counts disagree and it is a repeat request, and he knows that without anybody telling him. It is the oldest checksum there is, and it is why this page asks you to put the spaces in — without the gaps there is nothing to count.

What to do here

  • Press Start and do not stop for anything.
  • Space between groups, as you would on the machine. The count at the end depends on it.
  • Miss one, leave it, carry on. Do not go back — you cannot anyway.
  • Prosigns are one sound but two letters: BT for the separator, AR for end of message.
  • The paper stays open for a few seconds after the sending stops, so finish the group you are on. Press Enter when the copy is done.
  • Nothing is marked, and nothing on this page shows the answer, until you finish.

Where to go next

If this is too hard yet, that is normal — the mill is not where anybody starts. Practice marks every character as it lands and lets you correct, which is the right way to build the speed first. The course starts further back still, with two characters. Come back here when copying a whole message without stopping sounds possible rather than absurd.

The message format used here is a drill, built to have the parts worth copying — a precedence, a date-time group, a from and a to, a count and an ending. It is not a reproduction of any particular service's procedure. If you worked these circuits and something here is wrong, say so and it will be corrected.