[comp.sys.mac.hardware] Software controlled screen brightness on Mac Classic <-Need info

busey@blake.u.washington.edu (Thomas Busey) (10/30/90)

A recent spec sheet indicated that the Mac Classic's screen brightness
is software controlled via the Control Panel.  Does anyone have more 
information about this, especially 1)  how many different levels are
provided (just 8 like the sound volume or hopefully 256) and 2) can this 
be done with software other than the control panel (like from Pascal).
Thanks.
Tom Busey	Busey@blake.u.washington.edu

c252-aj@cinna.uucp (Trevor I. Blumenau) (10/30/90)

In article <10195@milton.u.washington.edu> busey@blake.u.washington.edu (Thomas Busey) writes:
>A recent spec sheet indicated that the Mac Classic's screen brightness
>is software controlled via the Control Panel.  Does anyone have more 
>information about this, especially 1)  how many different levels are
>provided (just 8 like the sound volume or hopefully 256) and 2) can this 
>be done with software other than the control panel (like from Pascal).

Ooh, sounds interesting!  They (the almighties at Apple) probably thought
of this, but what happens to the poor sole who turns his brightness all
the way down, and consequently cannot see what he's doing to turn it up
again?

Trevor Blumenau

blumenau@cory.berkeley.edu or c252-aj@cordelia.berkeley.edu

tj@kona.cs.ucla.edu (Tom Johnson) (10/30/90)

In article <10195@milton.u.washington.edu> busey@blake.u.washington.edu (Thomas Busey) writes:
>A recent spec sheet indicated that the Mac Classic's screen brightness
>is software controlled via the Control Panel.  Does anyone have more 

Yet another new thing with these new machines that I don't like! :->
The brightness can only be controlled by the Brightnes cdev.  It cannot
be set to completely black Otherwise, how would you ever set it back?
Hunt around the screen, clicking randomly until you happen to click on
the cdev's slider control? And the value you select is not stored
on restart.  It appears to be reset to some median value, which, of course
is not what you would have picked, if given the choice.            

Somethimes we pay a terrible price for innovation (like usefullness).

Tom

-- 
Tom Johnson      UCLA Computer Science Department 
			3413 Boelter Hall, Los Angeles CA 90024 (213)825-2145
			Internet:  tj@cs.ucla.edu

russotto@eng.umd.edu (Matthew T. Russotto) (10/30/90)

In article <40750@shemp.CS.UCLA.EDU> tj@kona.cs.ucla.edu (Tom Johnson) writes:
>In article <10195@milton.u.washington.edu> busey@blake.u.washington.edu (Thomas Busey) writes:
>>A recent spec sheet indicated that the Mac Classic's screen brightness
>>is software controlled via the Control Panel.  Does anyone have more 
>
>Yet another new thing with these new machines that I don't like! :->
>The brightness can only be controlled by the Brightnes cdev.  It cannot
>be set to completely black Otherwise, how would you ever set it back?
>Hunt around the screen, clicking randomly until you happen to click on
>the cdev's slider control? And the value you select is not stored
>on restart.  It appears to be reset to some median value, which, of course
>is not what you would have picked, if given the choice.            

Long ago, I wrote a DA (an ugly one, too) for an ancient machine known as the
Lisa.  The characteristic of the Lisa most important for this thread is that
it, also, had software-resettable contrast, and that MacWorks, the Mac
emulation software for this dinosaur, provided no provision to change.  Apple,
in their infinite wisdom, provided no documentation on how to change it.
Fortunately, I was able to figure it out, and wrote this DA to change the
contrast, plus an INIT to set it on MacWorks startup.  (the DA also did other
neat things, like setting the brightness level for the built in screen
saver-- also restored on startup, plus shut the machine down for a certain
amount of time, after which it would turn back on).  Perhaps someone in
a similair situation with a Classic will write an INIT to restore the control
panel brightness on boot.

(BTW, I'll write one for you-- just send me a Classic 2/40. :-) ...)

Now, of course, a really slick person will make a hardware device which hooks
into the ADB and can be hooked onto the side of the keyboard.  It will have
a little knob in it which will send signals to a driver which will change the
screen brightness.  They'll call it-- a brightness knob-- and charge $50.00
or so for it :-)
--
Matthew T. Russotto	russotto@eng.umd.edu	russotto@wam.umd.edu
Tax the rich, and feed the poor -- until there are, rich no more.

murat@farcomp.UUCP (Murat Konar) (11/02/90)

In article <29348@pasteur.Berkeley.EDU> blumenau@cory.berkeley.edu (Trevor I. Blumenau) writes:
>>A recent spec sheet indicated that the Mac Classic's screen brightness
>of this, but what happens to the poor sole who turns his brightness all
>the way down, and consequently cannot see what he's doing to turn it up
>again?
>

This was a problem with early versions of the system software for this beast.
You could get yourself into the situation where the screen was black and there
was no hope of feeling your way around to find the dimmer control.  The 
escape hatch was (if I recall correctly) that you could also use the 
number keys to adjust the  brightness.  

The current (sensible) approach is that you cannot turn the screen brightness
down  to zero from the control panel.

-- 
____________________________________________________________________
Have a day. :^|             
Murat N. Konar	
murat@farcomp.UUCP             -or-          farcomp!murat@apple.com