Path: utzoo!attcan!uunet!aplcen!uakari.primate.wisc.edu!sdd.hp.com!hp-pcd!hpcvra!prestonb
From: prestonb@hpcvra.CV.HP.COM (Preston Brown)
Newsgroups: comp.sys.handhelds
Subject: Re: The hp48sx screen-fade
Message-ID: <25590005@hpcvra.CV.HP.COM>
Date: 30 May 90 18:58:26 GMT
References: <9909@hydra.gatech.EDU>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 13

Actually, you are putting the display controller into test mode.  This
is used for hardware testing during the IC manufacturing; its not designed
to be used by the user.  This is not a really good thing to do to your 
calculator because it puts a DC bias onto the display.  If you left it like 
that for a long time it may dammage your display.  

The area from 0100-013F in memory are the hardware control registers
100 - [DON OFF2 OFF1 OFF0]        Display on, bit offset
101 - [CON3 CON2 CON1 CON0]       display contrast control
102 - [VDIG LID TRIM CON4]        display test and high contrast bit.
                     VDIG LID and LTRIM should be left 0.

Preston