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DOS “Screen Saver”?

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neosunrise

Experienced Member
Joined
Jan 17, 2019
Messages
139
Location
Chicago, IL
I have a few vintage computers with monochrome phosphor monitors. I do not use them much but would like to keep them on for a short while (perhaps half an hour) on a regular basis, in order to prevent electrolytic capacitors from drying out. I do not want to any burn in to happen during this process. Is there any way I can use some program to completely turn the screen into black so nothing is shown on it? I don’t really want to use those “screen saver” programs which may have different things displayed on the screen because it still burns the phosphor over time. I am thinking of a BASIC program or similar thing. I’d like to write it into a floppy disk so it can just boot into BASIC and run the program automatically.

Any thoughts?
 
neosunrise said:
I do not use them much but would like to keep them on for a short while (perhaps half an hour) on a regular basis, in order to prevent electrolytic capacitors from drying out.
Any thoughts?
Click to expand...

Turning them on maintains the dielectric. It doesn't prevent them from drying out, which will happen to all electrolytics eventually.
 
Half an hour is not going to cause any burn. It takes months or years of use, not minutes.

If a screen saver is used there will be zero ill effects in half an hour as it would take infinitely longer to cause any burn, which, BTW, would be necessarily uniform across the entire screen. :)

I like to use Explosiv which is a user configurable fireworks display. It can also be set to turn the screen black immediately or after a set period of time.
 
If the monitors have brightness controls, just turn them down so you can just barely see the image.

There were various shareware DOS TSR "screen blankers", although I don't remember any exact names. If you are that concerned about burn in, those would be a good thing to add to your standard boot.
 
I still may have a couple of "monitor miser" boxes. Essentially, it's a timed switch that turns off your monitor if you don't have any keyboard activity for a preset time. I was conflicted about the things because cycling power can be hard on electronics.
 
Chuck(G) said:
I still may have a couple of "monitor miser" boxes. Essentially, it's a timed switch that turns off your monitor if you don't have any keyboard activity for a preset time. I was conflicted about the things because cycling power can be hard on electronics.
Click to expand...
That defeats his intended purpose. He wants to leave the monitor on during this exercise.

Here's some more screen blankers:

http://www.pc-tools.net/dos/blackout/

http://www.lanet.lv/simtel.net/msdos/screen-pre-bydate.html
 
Stone said:
That defeats his intended purpose. He wants to leave the monitor on during this exercise.
Click to expand...

The original idea was to save power (hence the "Green" appellation on the box). CRT monitors back in the day, were notoriously power-hungry, when compared to the CPU box.

Tell that to a guy with an 8-core liquid-cooled gaming rig today...

I've never understood why there are screen savers for LCD panels.
 
Chuck(G) said:
I've never understood why there are screen savers for LCD panels.
Click to expand...

The only modern day purpose to a 'screen saver' is as a privacy screen. In some locations with private data (hospitals, banks, etc), it helps to keep the information on the screen slightly more secure if the user walks away without taking proper precautions. Personally I just set windows to turn off my display after about 20 minutes of inactivity, but where I work, the screensaver is specifically used as part of security policy (on systems where they can't have it auto lock/logoff).
 
Okay thanks guys for all the info, very helpful! I just tried EXPLOSIV suggested by Stone and it seems to work perfectly fine. btw, how often do you turn on your computers to ensure everything is okay?
 
commodorejohn said:
Hex dump of BLANKER.COM, which I just threw together:
Code: 
B4 0F CD 10 30 E4 24 7F CD 10 B4 01 B9 00 20 CD 10 30 E4 CD 16 B4 4C CD 21
Click to expand...

This is precisely what I yoosta do. It sure beats the flickery animated stuff that eats up 256kB.

Screen savers might not be necessary for LCD displays, but they sure are for plasma displays. Of course, no one really understands screen savers (for two decades!) so it's common to see a "screen saver" image burnt in.
 
KC9UDX said:
This is precisely what I yoosta do. It sure beats the flickery animated stuff that eats up 256kB.

Screen savers might not be necessary for LCD displays, but they sure are for plasma displays. Of course, no one really understands screen savers (for two decades!) so it's common to see a "screen saver" image burnt in.
Click to expand...

Ya, but why do you care how much it uses if the thing is at 'parade rest' anyway. :p
 
Just as another option: Norton Commander (at least version 5) contained quite a few screensavers. They could also be started instantly by moving the mouse into a corner.
 
IMHO, the simplest solution is to have this in AUTOEXEC.BAT;
Code: 
echo off
cls
You'll still have a blinking cursor but I doubt that will cause any screen burn-in. :)

commodorejohn said:
Hex dump of BLANKER.COM, which I just threw together:
Code: 
B4 0F CD 10 30 E4 24 7F CD 10 B4 01 B9 00 20 CD 10 30 E4 CD 16 B4 4C CD 21
Click to expand...
Optimized it a bit. :D
Code: 
B4 0F CD 10 83 E0 7F CD 10 B4 01 B9 00 20 CD 10 30 E4 CD 16 C3
 
Run DEBUG, and enter something like:

f b800:0 l 1000 0
(for color video)

f b000:0 l 1000 0
(for monochrome video)
 
there is a very good, compatible, easy to configure and total screen blanker that has a tiny footprint from the early 90s called Blank-it. it also has switchs to enable and disable it at the prompt or via a batch file
 
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