CRT Video Function BIOS Interrupts. int 10h

[lord loh.]

I tried to set the video mode to 12h (640x480 VGA) and saw all distorted characters. I am using a 17" LCD Screen and my windows display properties refuses to go below 800x600 Is it possible to use 600x800 display from the native BIOS routines or diaplay 640x480 on an LCD?

 

[Nigel Goodwin]

If your Windows properties won't go below 800x600, it sounds likely that the monitor doesn't support that mode?. You can certainly use 800x600 from DOS, but you will probably have to write your own driver routines?, unless your compiler includes a suitable library for your specific card, or at least the mode it uses. The Borland compilers used to provide BGI's (Borland Graphics Engine) files which actually drove the video card.

 

[Hero999]

Is this an assembly program running in DOS?

I've never had any problems with my 1280x1024 TFT monitor using lower resolutions; it works all the way down to 320x200!

Are you sure you're getting the assembler to recognise it as a hexadecimal number?

What assembler are you using?

Could you please post the source.

You can get Windows to go down to 640x480, in the settings panel click on advanced, under the adaptor section click on list all modes.

You could also try QBasic which can be downloaded from the MS website.

**broken link removed**

Run olddos.exe from a DOS box after using CD to change to the directory where you want to install it.

Try mode 12h by typing SCREEN 12 in the immediate box and pressing enter.

 

[Sceadwian]

Depends on the monitor, some have better scaleing circuits than others and yours may not be able to scale from to that particular resolution. Need to check the manul for your monitor.

 

[Hero999]

I don't believe that the monitor is the problem in this case. I think it's far more likely he isn't programming the graphics card correctly. If you try to get a modern TFT monitor to display a mode it doen't like its onscreen display will display an error message.

 

[lord loh.]

Reference: https://www.ctyme.com/rbrown.htm

I am using NASM

And am using BIOS interrupt to se the video mode....

All I am using is int 10
as described here.... https://www.ctyme.com/intr/rb-0069.htm

And I get some blotched images on the screen vaguely identifiable as text... That too because I know what I attempted to print....

 

[Sceadwian]

Sounds to me like the LCD monitor doesn't support the resolution properly. Have you tried it on a CRT monitor?