[GreenKeys] How does keyboard actually connect to printer model 19/15

[Jim Haynes]

Model 19i has the K-KT-T switch, which means Keyboard, Keyboard&Tape,
and Tape.  In K and KT positions the keyboard is mechanically connected
to the signal generator which is like that of a Model 15.  So in fact
in the K position the machine is basically a Model 15.  If the keyboard
soignal generator is connected to a local loop including the printer
you get local copy of whatever is typed on the keyboard, which might also
be transmitted out to another machine.

In the KT position the keyboard signal generator might be in a local loop
with the printer, so you punch tape for later transmission and make a 
readable copy on the printer.  Which might be desired by a casual
operator to see what is on the tape about to be transmitted.

In K and KT positions the signal generator coupled to the keyboard
means the keyboard speed is limited to whatever the machine is geared
for, typically 60 or 75 wpm.

In the T position the keyboard is disconnected mechanically from the
signal generator, which prevents making printed copy of what is in
the tape but allows an expert operator to punch tape very fast.  The
expert operator is expected to be able to read the punched characters
in the tape and so does not need a printed copy to see what will be
transmitted.

A basic Model 19 is not able to punch tape from incoming signals.
Doing tht requires an auxiliary reperforator.  When present this sits
on a little table on casters under the main table.  An alternate location
is on a bracket that holds it above the XD on the main table.

I call Model 19 an American ASR set, in contrast to the European style
to be described below.

The K-KT-T switch can be confusing to operators since there are
other optional ways of wiring a set that affect what it does.

The European style ASR set, of which the American Model 33 is an
example, has the tape punch operated by the printer mechanism.
The tape reader is associated with the keyboard so only one of those
may be ued at a time.

I put together a Model 35 ASR set the way I thought it should be done.
The assumption is that there is  line circuit for whatever the machine
is to be used for, and a local circuit for testing, typing practice,
printing hard copy from a tape, punching incoming traffic into tape
and whatever else might be needed, and being easy to understand.

The keybord and printer have toggle switches marked LINE-LOCAL.  The
reperforator and tape reader have pushbuttons for LINE-LOCAL-OFF.
The pushbuttons control relays which control the signal flow.  This
allows for such things as incoming signals that turn the punch on and
off, and that turn the tape reader on and off.  Isn't that more 
transparent than K-KT-T?

Jim W6JVE



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