Stefan: That's a pretty hazardous guess, all right.

ASCII (uppercase only) didn't come on the scene until
1963. If you want lowercase, then that's 1967.
There's good history overview (although nothing will
likely ever be authoritative) at
http://www.wps.com/texts/codes/

Even some 1970's technology looks quite mechanistic.
I used to have a 1970's era 'glass teletype'. It had
a separate monitor, but the box was the size of a
classic IBM PC - and all it did was be a 80x25 terminal.
The keyboard was housed in a 1/16" steel shell, and had
a many-many-many pin connector (50, perhaps?). Inside
- yes, of course I opened it - it was all discrete
logic. Individual gates and stuff. Real technical
tour de force in its day. It even had random cursor
movement!!

Actually, although the monitor is long gone, I think
my parents still have the box and keyboard in their
basement somewhere. For the sake of history, I should
dig the darn thing out, photograph it, and document
it. Given it's construction, it likely still works...