[TUHS] Teletype simulator?

scj at yaccman.com scj at yaccman.com
Fri Mar 25 06:29:05 AEST 2016

All this talk about Teletypes brings up memories.  Model 33 TTY's were
single case and each "key" (which was tubular) had to be pressed down over
1/4 inch to register.  It was a significant effort.  The model 37 TTY's
that came along a few years later were upper and lower case (Unix was one
of the few OS's at the time that could handle both cases smoothly).  But
if you opened the case, what was in it was an astonishing assembly of
cams, levers, and other mechanisms.  When glass TTY's came along, they
took over quickly.

One of my most vivid memories of "paper" TTY's happened at my home, early
in my Unix experience.  The TTY had a box of paper feeding it, and the
output was also allowed to pile up behind it.  This "used" paper served a
critical role.  At the time, Unix had two kinds of files -- small and
large -- and if the system crashed (not uncommon in those days) when your
file was in transition from small to large the contents of the file were
lost.  It was also frequently the case that updates were lost in files
being edited.  So when the system crashed, you would haul up the terminal
output and highlight the changes that you made in case you needed to enter
them again.  This typically took a few minutes, by which time the system
was up again and you could start to reenter your changes.

So one day, I was heavily into editing when my wife, in the kitchen,
needed help with the kids so I went to help her out, leaving the terminal
running.  It was several hours before I was able to get back to it, at
which point I discovered that not only had the system crashed, but our cat
had discovered an alternative "litter box" behind the terminal and made
use of it!  Luckily, it was pretty dry by then, but that didn't help the
smell.  And, so help me, holding my breath I marked the lines that needed
to be reentered...

The other TTY story that surfaced happened to Dennis.  He had one of the
last model 37's as his home terminal, and it was getting quirky.  The
vibration of the mechanism occasionally caused a blank space to be
generated that he hadn't typed.  In those days, it was common to delete
the .o files after compiling because disc space was precious.  So Dennis
"rm *.o" and Unix replied ".o not found".

> That sounds like the Teletype model 33, and probably other Teletypes.
> If you don't give it the extra .1 second of the LF, the first printed
> character will overstrike in the middle of the line you just typed.  And
> it will be "bold" because the print head is moving very fast to the left.

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