David Griffith wrote:
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I have a couple vintage sounders. Hook a batter and key in serial with
a sounder. When the key is down, the sounder clicks down. Let go and
it clacks up. So, a dot is "click-clack" and a dash is
"click-wait-clack". I think the Mark and Space stuff has to do with the
fact that the line was always kept energized, thus, an idle line would
hold the sounder arm down. That way you'd know immediately if there was
a line fault. That would be a bit wasteful now, so I suppose I should
preceed each message with a very long dash to at least try to fake that
part.



As I recall there is international Morse Code and American Morese code..
Two different codes, and one (American I think) is better suited to the
click/clackers and guess what.. That font of much knowledge

http://en.wikipedia.org/wiki/American_Morse_code

Has an article on it at the above link INCLUDING the code itself!!!!

Also called the Railroad code.. IT is not as suited to radio as
International Morse code is.

As to the line running energized.. There are several reasons for this,
Many countries the phone system keeps current flowing in the wires all
the time, this is called "Sealing Current" and if you have the manual
for an old 300 or 1200 baud modem lying about you can read all about it.

The reason for this is to PREVENT line faults, believe it or not. As
well as instant detection of line faults.

Modern teletype (BAUDOT and later ASCII teletype machines) like the Type
15, 28 and 33 all used idle on MARK

One of the more interesting lengths of paper tape I used to have was
punched by one of the national news wires one November back in what,
1963 (The 23th as I recall) You play the tape and it starts typing out
routine items (I recall a farm report or some such but it's been many
years since I played the tape) then suddenly the machine runs "OPEN"
(Space) for a period and then the news flash.. Then it goes back to
routine and again it runs open.. the operator intruppted sends "Go Ahead
Dallas" and we read "The president is dead"

That's some tape.