How to use parity space and mark

[Paul_KD7HB]

@Grumpy_Mike

I think it was the other way round. Mark is the un-driven state of the line and Space is the driven state.

Nope! The printing device replaced the telegraph sounder. When the operator on the other end of the line pressed the key down, current flowed in the line and magnetized the pencil control. The normal, key-up, was always NO current.
Paul