int10h is the API (BIOS)... that just causes the mode switch. What he really meant (direct RAM access): void putpixel_13h(int x, int y, int color) {

int10h is the API (BIOS)... that just causes the mode switch. What he really meant (direct RAM access): void putpixel_13h(int x, int y, int color) { _farpokeb(_dos_ds, 0xA0000+y*320+x, color); }