[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Trailing "m"s at the end of every line when viewing man pages

On Sun, 05 Apr 2015 11:59:49 -0400 (EDT), Paul E Condon wrote:
> Times change. If one waits even a short while, they can change a lot.
> When this terminal was new, a 'standard' terminal was a mechanical
> teletype manufactured by Teletype Corp. in Skokie, IL.  The generic
> name for this 'terminal' was, I think, a 'glass teletype' Each
> computer company had its own special glass teletypes that interfaced
> to its computer. All proprietary.
> None of the glass teletypes had the very useful scroll back feature
> of the real teletype that they were trying to emulate. Teletype
> paper came in rolls. A single roll was a many meters long. It would
> pile up behind the teletype as one worked. It could always be pulled
> out and reviewed back to initial login at the beginning of the
> session. Some people left the paper behind for someone else to clear
> away. Others saved it, rolled up and labeled at their desks.
> It took 0.1 sec. to mechanically process one character, except for
> carriage return. That took up to 0.2 sec. The placement of the
> carriage return character before the non-printing line feed
> character allowed the carriage to get all the back to the left before
> a printing character arrived. It was in the design of teletype that
> this cr/lf feature was baked into our history.

Interesting history, thank you.  The IBM 3151 is a "dumb" terminal in
the sense that it doesn't support scrolling backward.  But my idea
of a "dumb" terminal is a line-mode terminal, such as a mechanical
teletype machine.  The IBM 3151 is a full-screen terminal.  You can
run ncurses-based applications on it.  You can use full-screen editors,
such as vi.  It supports high-intensity, underscore, blinking, and
reverse video, though it does not support color.  It supports
clearing the screen.  (It is a non-standard clear code, so the
standard code used by (a)getty does not clear the screen.  But the "clear"
command works.)  None of these things can be done on a line-mode (dumb)
terminal, such as a mechanical teletype machine.  It is more than a
"glass teletype".

  .''`.     Stephen Powell    <zlinuxman@wowway.com>
 : :'  :
 `. `'`

Reply to: