Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!nrl-cmf!ames!amdcad!sun!pitstop!sundc!seismo!uunet!mcvax!botter!ast
From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: How do you turn on the AT's LEDs?
Message-ID: <1836@botter.cs.vu.nl>
Date: 25 Jan 88 11:00:18 GMT
References: <1832@botter.cs.vu.nl> <4240@eagle.ukc.ac.uk>
Reply-To: ast@cs.vu.nl (Andy Tanenbaum)
Organization: VU Informatica, Amsterdam
Lines: 16

In article <4240@eagle.ukc.ac.uk> rde@ukc.ac.uk (R.D.Eager) writes:
>
>I  believe the LEDs are controlled locally by the keyboard hardware (the
>8248 or whatever it is). They are set OFF at reset, then toggled  "with"
>the  keystrokes.  I don't think you can control them down the wire...

As everyone with MINIX on an AT has observed, hitting caps lock does not turn
on the LED.  Thus if they are controlled by the 8248, it is doing a very poor
job.  Maybe somebody has to initialize the 8248 to tell them to do it, but I
doubt it.  Given the level of the keyboard interface (both make and break
are reported with interrupts, and scan codes rather than ASCII characters are
returned), I'd be surprised if LED driving were handled internally in the
keyboard.  Practically nothing else is.  Thus the question remains: does
anyone know how to turn them on and off (check your BIOS listing).

Andy Tanenbaum (ast@cs.vu.nl)