[TUHS] Happy birthday, Dennis Ritchie!

Steve Johnson scj at yaccman.com
Sun Sep 10 07:56:27 AEST 2017

Part of that problem was probably electronic, not software.   Many
of the early terminals were half-duplex.  The normal mode was that
the terminal typed what came over the line, and the keyboard was
locked.  If you wanted to let the terminal send data, you needed to
send a control character to unlock the keyboard, and then another one
to lock it when you wanted to send data again.

As you may know, the first PDP-11 at Bell Labs was financed by the
patent department because there were very draconian rules about
submitting patents (every page had to have exactly 50 numbered lines,
lines could not be blank, numbers must be in order, etc.)   A change
on page 3 of a 25-page patent application could mean that the whole
thing had to be retyped (yes, manually...).   That need drove a lot
of the early nroff work.  And, when upper/lower case terminals became
common, many still had half duplex interfaces.    When the Unix
software got good enough, it started to get used by real typists, who
were used to electric typewriters.  There was bitter complaint about
the half duplex (keyboard lock) mode -- the typists were so fast that
when the keyboard locked they could break their fingernails!  Full
duplex pretty much solved that problem, and Unix, as far as I
remember, embraced it earlier than most other systems.


PS:  The Usenix publication ";login:" got its name because that's
what a half-duplex system wrote for the login message when viewed on a
full duplex terminal.  The ; and : were actually control

----- Original Message -----
From: "Lawrence Stewart" <stewart at serissa.com>
To:"William Cheswick" <ches at cheswick.com>
Cc:"TUHS main list" <tuhs at minnie.tuhs.org>
Sent:Sat, 9 Sep 2017 16:33:54 -0400
Subject:Re: [TUHS] Happy birthday, Dennis Ritchie!

 What, you didn’t like IBM 2741 terminals that mechanically locked
the keyboard?

On 2017, Sep 9, at 9:04 AM, William Cheswick <ches at cheswick.com [1]>

Amen.  There were a number of things that really sucked at the time.
My least favorite: time sharing systems that didn’t allow

Kids these days...

On 9Sep 2017, at 12:34 AM, Steve Johnson <scj at yaccman.com [2]> wrote:

For people used to that world, "echo hello >hi" was literally jaw
dropping.  Many people had to have it explained twice, because they
literally could not conceive of a file being created so easily.  I
had worked in the computing center for a couple of years, and probably
gave more than my share of demos to mainframe users...


[1] mailto:ches at cheswick.com
[2] mailto:scj at yaccman.com

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