Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!mailrus!uflorida!gatech!udel!udccvax1!anand
From: anand@vax1.acs.udel.EDU (Anand Iyengar)
Newsgroups: comp.society.futures
Subject: Re: Keyboards - input devices
Message-ID: <2714@udccvax1.acs.udel.EDU>
Date: 19 Jan 89 22:36:20 GMT
References: <19626@uflorida.cis.ufl.EDU> <315@s1.sys.uea.ac.uk> <292@ultb.UUCP>
Reply-To: anand@vax1.acs.udel.EDU (Anand Iyengar)
Organization: The Lab Rats
Lines: 54

In article <292@ultb.UUCP> jdb9608@ultb.UUCP (J.D. Beutel (713ICS)) writes:
>A solution would be to have a tty driver that will map keys.  The user could
...
>No hardware would be affected, and the solution would allow a uniform and
>personal choice of a Dvorak or other such change-the-names-of-the-keys-but-
>don't-actually-move-any-around type keyboard.  
>
>I think such a tty driver would need only two changes from ones used now:
>	1)	enable it to read a key map
>	2)	any char it recieves is used as an offset into the key map to
>		determin the char that is passed along--i.e., translate
>
>A problem would be that reading a key map from disk every key stroke would be
>very inefficient, so the key map would need to be kept in memory with the tty
>device driver.  However, since each user might have a different key map,
>the device driver would need an array of key maps (less than or equal to 
>128*2 bytes per user record), or perhaps a limited number of pre-defined
>keyboard types corresponding to a user-modifiable minor device number?
>
>Are there any Un*x gurus out there that would care to comment on the 
>feasability of such an improvement to the tty driver?

	For a number of reasons, the modifications shouldn't really be
put in the tty driver, but since we're using unix it doesn't have to be.
Some time ago I wrote some code that does what you describe:  remaps kb input
according to a mapping file (for exactly that reason:  I wanted a Dvorak
keyboard, and the only terminals in the building that supported s dvorak
KB layout got locked up at midnight.  I either had to write some simple code to
remap keys, or change my work schedule.  Not a difficult choice...).  

	At first I tried forking off a shell, and subsituting a pipe for
stdin.  Fair idea, but the shell (shells, actually, I tried csh and tcsh) was
somewhat flakey about reading from non-tty's.  No big deal...the source for
_script_ (which, by definition does everything a (non-console) tty does) +
very minor changes (I had less than an hour to spend on it) met the specs.

	I've been told that since the script that I used is BSD-code I can
give away this source.  So:

	If you would like the code, send me mail (anand@vax1.acs.udel.edu:
see below) with your e-mail address, and I'll re-mail the source to you.  
You'll need a C compiler.  

	
							Anand.
--
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