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From: dan@rna.UUCP (Dan Ts'o)
Newsgroups: comp.emacs
Subject: Re: gnumacs bindings
Message-ID: <655@rna.UUCP>
Date: Sun, 20-Sep-87 17:46:43 EDT
Article-I.D.: rna.655
Posted: Sun Sep 20 17:46:43 1987
Date-Received: Sun, 20-Sep-87 23:39:30 EDT
References: <3590005@hpindda.HP.COM> <8709181153.AA08300@ucbvax.Berkeley.EDU> <636@unmvax.unm.edu>
Reply-To: dan@rna.UUCP (Dan Ts'o)
Organization: Rockefeller Neurobiology
Lines: 33

In article <636@unmvax.unm.edu> mike@turing.unm.edu (Michael I. Bushnell) writes:
>>It seems to me that this "cultural river" is relative.  Emacs started on a
>>system which used DELete to mean just that (and most of the terminals had a
>>nice DELete key!).  Some(how,when) Unix(tm) picked (first "#" and then)
>>BACKspace to mean delete.  (I assume some Unix guru's keyboard didn't have
>>a decent DELete key?)  Now Emacs runs on Unix systems, and Unix users are
>>used to BACKspace.  (But in:
>
>ACK!  NO!  NOT TRUE!!!!!!!!

	Not true, indeed. Remember that UNIX started as a very simple OS,
with a very simple TTY driver, back in the days of TTY's, like the TTY33.
Teletype was/is a part of the Bell System (Western Electric ?).
	The tty driver simply echoed incoming characters, with very few
exceptions, like mapping CR to LF and outputting CRLF. So echoing DEL
won't have been very useful: no feedback as to whether or how many characters
to delete. Thus # was not unreasonable. The same goes for the line kill
character: @. The DEL was (and is still used in SysV) as the interrupt
(like ^C), where echoing was irrelevant.
	Now, BS would also have been (and is) reasonable on CRT's, but
UNIX started on printing tty's, where the result is a mess. A more
complicated tty driver would have handled DEL like DEC did in OS's like
TOPS10 and RT11, by echoing the deleted character, in some cases surrounded
by \/:
	misteak\eak/ake

	But remember the UNIX kernel used to fit in under 16kbyte (8kwords).
Many early university UNIX systems hacked the UNIX tty driver to "bits",
adding all sorts of stuff like TENEX mode, and better DEL handling for CRT's.
So the original reason why BS got popular as the erase char in UNIX,
especially with standard non-BSD UNIX, is that the CRT terminal would handle
the cleaning up of the displayed line "automatically", without any help or
special code in the tty driver.