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BIOS video routine question

Name: Anonymous 2012-11-28 16:18

I was looking at https://singularity.svn.codeplex.com/svn/base/boot/SingLdrPc/blentry16.asm
and I'm confused by the BlInitializeVideo function.
Particularly this call to the bios video routines:
        mov     ax, 1202h       ; LINES_400_CONFIGURATION
        mov     bx, 0301h       ; SELECT_SCAN_LINE
        int     10h

That code sets AH=12h, AL=02h, BH=03h, BL=01h, right?
From the comments, it seems to be calling Int 10/AH=12h/BL=30h, listed here http://www.ctyme.com/intr/rb-0167.htm

Does anyone know what's going on in this code? Is there some funky bios thing going on or am I misunderstanding something?

Name: Cudder !MhMRSATORI!fR8duoqGZdD/iE5 2012-11-29 4:55

It's probably a bug, one that doesn't have much effect. The default is usually 720x400 80x25 mode anyway.

The e/b/inElpin VGABIOS code I have doesn't implement that function. At first I thought it might be vendor-specific; you could try checking MSVPC's BIOS to see if it was added for that environmnet.

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