Re: A86: Many Stupid Questions

To: assembly-86@lists.ticalc.org
Subject: Re: A86: Many Stupid Questions
From: Tercero <tercero@busprod.com>
Date: Wed, 19 Aug 1998 23:14:53 -0700
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Organization: BPS Internet
References: <3.0.1.32.19980818211924.00692acc@reninet.com> <35DAF859.D5B0C9F0@oregontrail.net>
Reply-To: assembly-86@lists.ticalc.org


Really bad things won't happen.

Load $1F into ($C008).  Nothing happens...
now use 2nd+down to lower your contrast.  Kapow!  Your contrast
is suddenly set to $1E.  (And your screen is veeerrry black).

Try it the other way around.  Load $1F into port 2.  Black screen!
try to lower the contrast and your contrast is restored to it's
original level minus 1.

This is why...  Every time you adjust the contrast in TI-OS it:
1) Reads from ($C008)
2) Modifies it to your beckoning.
3) Makes sure the new contrast level is legal (0 < contrast < $1F)
4) Writes the new value to the port and to ($C008).

-- 
Tercero	 --  Email: mailto:tercero@busprod.com

"The stone the builders rejected has become the capstone;"
			--Psalms 118:22
"Everyone who falls on that stone will be broken to pieces,
but he on whom it falls will be crushed."
			--Luke 20:18

References:

Re: A86: Many Stupid Questions

From: Chicane <chicane@reninet.com>

Re: A86: Many Stupid Questions

From: Cassady Roop <croop@oregontrail.net>