Editing Mode 13h (section)

=== Source code examples ===

Assembly code to enter Mode 13h:
<syntaxhighlight lang="asm">
mov ax, 0013h
int 10h
</syntaxhighlight>

As an illustration of mode 13h in a video game source code, [[Wolfenstein 3D]] includes this function in a file named "ID_VL.C". It enters mode 13h by using two assembly instructions (prefixed with <code>asm</code>) embedded in the C source code.<ref>https://github.com/id-Software/wolf3d/blob/master/WOLFSRC/ID_VL.C#L108</ref> This function also executes three other functions.
<syntaxhighlight lang="c">
void    VL_SetVGAPlaneMode (void)
{
asm     mov     ax,0x13
asm     int     0x10
        VL_DePlaneVGA ();
        VGAMAPMASK(15);
        VL_SetLineWidth (40);
}
</syntaxhighlight>
''[[Wolfenstein 3D]] source code (circa 1992) which calls the BIOS to change to mode 13h.''