From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
From: "Thomas Bushnell, BSG" <tb+usenet@becket.net>
Message-ID: <87n0z5neel.fsf@becket.becket.net>
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable
References: <20020122182852.0CEC719981@mail.cse.psu.edu>, <3C4DE321.D4726662@null.net>
Subject: Re: [9fans] Getting started in Plan9 - help
Date: Wed, 23 Jan 2002 18:01:04 +0000
Topicbox-Message-UUID: 423db408-eaca-11e9-9e20-41e7f4b1d025

"Douglas A. Gwyn" <DAGwyn@null.net> writes:

> David Gordon Hogan wrote:
> > What _really_ annoys me is when I hit the BACKSPACE key on
> > the keyboard, while running some terminal emulator, and it
> > sends DELETE.
>=20
> DEC actually started making terminals like that!
>=20
> > the default should be that backspace is backspace.
>=20
> I agree..

The ASCII standard fortunately solves this one, and you're both wrong.

The ASCII BS charactec is specifically to help the "backup and
overstrike" operation.  For example, =E0 is supposed to be rendered as=20

  a BS `

The ASCII sequence for "ignore last character transmitted" is:

  BS DEL

That is, DEL is *overstruck* on a character to delete it.  Note the
nice way this works on paper tape: DEL is all-ones, so that means a
paper tape reader should ignore all-ones.  It's also supposed to
ignore NUL (all-zeros); some hardware could not be relied upon to deal
so accurately with spacing, and false reads of all-zeros would happen.

Thomas