This is the one that returns the array of all supported video modes

push word 0
pop es
mov ax,0x4f00 ;biosint
mov di,0xa000 ;address of return VBE info block buffer
int 0x10
cmp ax,0x004f
je vesaisok
=============================================================

Get Mode Info. With CX=graphicsmode, ES:DI=256 byte buffer

clc
mov ax, 0x4f01
int 0x10
cmp ax, 0x004f
jne .failed
ret
.failed:
stc
ret
=============================================================

followup: http://goahomepage.free.fr/auteur/prod/doc/vbe/index.html