[GreenKeys] Murray and Baudot codes etc.

[Richard YOUL Brisbane]

Gil was asking about early Murray codes, wnd how they evolved.

Firstly Murray was a New Zealander, apparently doing some work in Australia
before going overseas.

The Telstra (Telecommunications) museums in Brisbane and Sydney both have
working displays of Murray Multiplex. At each museum there is a keyboard
perforator and associated transmitter. The phonic wheel distributor causes
the transmitter (a rather small box) to step the tape from character to
character, and reads the code in sequence. Connections in the phonic wheel
control box feed these signals to a Morkrum page printer.

The Murray was introduced in this country around 1920, and from what one of
our old members once said, the first printers were the tape variety, but by
the mid 20s the Morkrum page printer was introduced and from then all post
office telegraph traffic was on page printers.

The keyboard, which probably interests you the most, is a standard QWERTY
design, but some of the control functions were different. There are in fact
two space bars, one for Letters-shift and space, (code is unit 3) and
Figures-shift and space (code 1245). In International No. 2 code these
combinations are now used for Space and Figs. What is now Letters shift
(12345) was used only for the erase function. The problem with the Murray
arrangement is that it was impossible to send a combination such as 12B34.
It would come out as 12 B 34. From memory the figures and punctuation are in
the same position as on our later teleprinters. If you need further details
I will be happy to check the keyboard in detail next time I visit the
museum. A photo could be possible.

Australia also used the Model 12 teleprinter, but it appears no keyboard
transmitters were ever saved, but they were used with the Morkrum printers
via a start/stop device (we have 2 of these) so the keyboard layout must
have been the same on the model 12 as the MUX. It apparently took some skill
to operate the Model 12. Transmission to line was 'live' and there was no
tape or 'end of line' indicator. It was up to the operator to estimate when
a line was nearly full to avoid overtyping on the page printer at the far
end of the line.

One further point about the MUX was the tape feed holes. On standard
teleprinters the feed holes had their centres in a straight line compared to
the signal holes. On the Murray, the leading edge of all holes formed a
straight line across the tape. Thus you could tell at a glance which way the
tape should go through the transmitter. This small offset is enough to make
transmission unreliable if playing a Murray tape in a teleprinter
transmitter.

Richard Youl
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