writing directly to vram

how exactly do you write directly to vram? If someone just has a site to look at that's all i need. What i mean by this is, how would a person write text to the screen with out calling dos, or the bios? Since I have a boot strap and I dont have dos, and i am in protected mode so i can not make bios calls any more, so i have to move the char's to video memory, but for one I dont know where the address is, so if anyone has any info on this could you please help? THANK YOU IN ADVANCE!!!