Comment Damn kids (Score 2, Informative) 582
Back in the DOS days, any moderately competent programmer knew how to copy arbitrary data to screen buffer, allowing you to display text without any libraries. It's been many years, so I am probably getting this wrong, but in psuedocode it'd look something like
char*cp="Hello World";
char *addr=0xB8000000;
while(*addr++ = *cp++);
That's the C version, of course. You'd actually do it in assembly. My suspicion is that you could do it in on the order of 20 to 25 bytes, but again, it's been decades since I've done anything like that.