[GreenKeys] Navy abandons M28 compatibility

[John Nagle]

   I don't know if any Morkrum Blue Code machines still exist.
As of 1983, Teletype Corporation had one in their collection.

    http://www.baudot.net/docs/slayton--tty-patents.pdf

   The Blue Code machine was a collection of relays and
solenoids which sat underneath an Oliver typewriter.
It had three shifts: UPPER, NUMBERS, and UNSHIFT
(i.e. lower case).  It was a start-stop binary 5-level machine,
what we're used to in later machines. There were earlier Morkrum
machines which used a 3-level 4-value code, where each symbol
time could have either a high or low current or positive or
negative polarity.  That was a dead end, at least until the
era of self-equalizing modems in the 1980s.

				John Nagle

On 6/9/2013 9:45 PM, COURYHOUSE at aol.com wrote:
> Wow. did not realize there was an upper lower  case machine that   early!
> I bet they are  scarce!?
> Ed#
>  
>  
> In a message dated 6/8/2013 11:33:52 A.M. US Mountain Standard Time,  
> nagle at animats.com writes:
> 
> That was originally for backwards compatibility with Morse code.
> Morkrum's  first machine, the Blue Code machine (1910) had upper
> and lower case  characters, with three shifts, LOWER, CAPITALS,
> and FIGURES, and a 3-row  typewheel.  But printing telegraphs
> were originally used only on main  lines, so the same message
> would also go over a Morse link.  Lower  case info was lost
> in Morse transmission.  Western Union asked for  machines
> without lower case, and that's how it all started.
> 
> John  Nagle
> 
>