tbechtel@polyslo.CalPoly.EDU (TrevorB) (03/02/90)
pas@lcs.mit.edu (Paul A. Selkirk) writes: >Does anyone know of a bulletproof way for a TSR to tell whether DOS (assume >2.x or 3.x) is idling in the command interpreter, or executing a program? not off hand... >For the record, I am writing a screen-saver TSR that will only trigger when DOS >is idling. There are dozens of screen-savers, but I need one that won't kill >a lengthy graphics program. (Ever try generating the Mandelbrot set on a 4.77 >MHz XT with no FPU? I thought so.) How about this, run the screen saver off of the timer interrupt. If the correct amount of time has passed, then change the pallette to all black (if EGA or VGA) or do a memory copy of the screen and blank it (if < EGA). While the screen is blank, the screen saver won't stop any program that's currently running, but will latch on to the keyboard or mouse interrupt. And, of course, when the keyboard/mouse interrupt is caught, you simply restore the screen by restoring the palette (if >= EGA), or copy the screen back into video memory (if < EGA). This sounds like it might be a more elegant solution and you won't have to worry about losing that Mandlebrot you've been generating for the last xx hours...and probably just as important, it won't stop that Mandlebrot while it's generating. The only thing that could hurt this is that if a program decides to modify the palette while the screen is blanked. I don't know EGA very well, but I bet there's probably a way to intercept incoming commands to change the palette, and what you'd do is intercept that and change what you've saved the palette as appropiately. TrevorB -- _____ _____ _____ _ _ ___ _____ _____ (_ _) | _ \ | ____) | | | | / _ \ | _ \ InterNet: | _ ) | | | _ / | __)_ | |_| | ( (_) ) | _ / tbechtel@polyslo. | _ ( |_| |_| \_\ |_____) \___/ \___/ |_| \_\ calpoly.edu |_____)
CMH117@psuvm.psu.edu (Charles Hannum) (03/02/90)
Uh, to elaborate ... The program I referred to in my last article *will* allow whatever you're running to continue.
zmact61@doc.ic.ac.uk (D Spinellis) (03/03/90)
In article <25ed7a61.29c1@polyslo.CalPoly.EDU> tbechtel@polyslo.CalPoly.EDU (TrevorB) writes: > >pas@lcs.mit.edu (Paul A. Selkirk) writes: >>Does anyone know of a bulletproof way for a TSR to tell whether DOS (assume >>2.x or 3.x) is idling in the command interpreter, or executing a program? [...] >>is idling. There are dozens of screen-savers, but I need one that won't kill >>a lengthy graphics program. [...] >How about this, run the screen saver off of the timer interrupt. If >the correct amount of time has passed, then change the pallette to all >black (if EGA or VGA) or do a memory copy of the screen and blank it >(if < EGA). While the screen is blank, the screen saver won't stop >any program that's currently running, but will latch on to the >keyboard or mouse interrupt. And, of course, when the keyboard/mouse >interrupt is caught, you simply restore the screen by restoring the >palette (if >= EGA), or copy the screen back into video memory (if >< EGA). You don't need to mess with screen copying and pallette saving and restoring. The following code will do the trick for VGA by setting a bit in the sequencer that indicates that video access to the memory should be dissabled. The result of this is that the screen blanks. mov dx,3c4h ; Sequencer index mov al,1 ; Clock register out dx,al inc dx ; Point to data in al,dx ; Get it or al,20h ; Set video disable bit out dx,al ; And set it On the other cards (CGA, MDA etc.) you clear the screen enable bit in the mode select register. The following code illustrates it: data segment at 40h org 49h crt_mode db ? crt_cols dw ? crt_len dw ? crt_start dw ? cursor_pos dw 8 dup(?) cursor_mode dw ? active_page db ? addr_6845 dw ? data ends mov ax,40h ; Address of data area assume cs:code,ds:data,es:nothing mov ds,ax ; Establish addressability mov dx,addr_6845 ; Primary card address add dx,4 ; Address of 3X8 register (mode select) mov al,crt_mode_set ; See old value and al,not 1000b ; Make the display enable 0 mov crt_mode_set,al ; Save it out dx,al ; Out it Diomidis -- Diomidis Spinellis Internet: dds@cc.ic.ac.uk Department of Computing UUCP: ...!ukc!iccc!dds Imperial College JANET: dds@uk.ac.ic.cc London SW7 2BZ #include "/dev/tty"
mlord@bnr-rsc.UUCP (Mark Lord) (03/07/90)
In article <25ed7a61.29c1@polyslo.CalPoly.EDU> tbechtel@polyslo.CalPoly.EDU (TrevorB) writes: >(if < EGA). While the screen is blank, the screen saver won't stop >any program that's currently running, but will latch on to the >keyboard or mouse interrupt. And, of course, when the keyboard/mouse >interrupt is caught, you simply restore the screen by restoring the >palette (if >= EGA), or copy the screen back into video memory (if >< EGA). Ok.. I'll bite. Does anyone know of a screen saver that REALLY succeeds in this endeavor? EVERY one I have tried (10+) has flunked the graphics + mouse test. Ie.. there I am, working away with a graphics program + mouse (FRACTINT), and .. kapooeee.. the screen goes blank, regardless of mouse activity! -- ______Mark S. Lord______________________ ______________________________ | ..uunet!bnrgate!carrsc!mlord | These are only MY opinions. | | or: bnr-rsc!mlord@bnrgate | I charge for official views. | |________________________________________|______________________________|
schow@bcarh185.bnr.ca (Stanley T.H. Chow) (03/08/90)
In article <2276@bnr-rsc.UUCP> mlord@bnr-rsc.UUCP (Mark Lord) writes: >In article <25ed7a61.29c1@polyslo.CalPoly.EDU> tbechtel@polyslo.CalPoly.EDU (TrevorB) writes: >>(if < EGA). While the screen is blank, the screen saver won't stop >>any program that's currently running, but will latch on to the >>keyboard or mouse interrupt. And, of course, when the keyboard/mouse >>interrupt is caught, you simply restore the screen by restoring the >>palette (if >= EGA), or copy the screen back into video memory (if >>< EGA). > >Ok.. I'll bite. > >Does anyone know of a screen saver that REALLY succeeds in this endeavor? > Hi Mark. Well, the screen saver that comes with PowerPak from MultiSoft does this correctly. All you should have to do is load the mouse driver first. I am not sure if it blanks the screen by playing with the palette, but it does read both the keyboard and mouse. Stanley Chow BitNet: schow@BNR.CA BNR UUCP: ..!psuvax1!BNR.CA.bitnet!schow (613) 763-2831 ..!utgpu!bnr-vpa!bnr-rsc!schow%bcarh185 Me? Represent other people? Don't make them laugh so hard.