Mode X is a slang name for a VGA hack that achieves 320x240 in 8-bit colour with square pixels. I recommend you read up on it in Michael Abrash's Black Book, he explains all the VGA options very well. It's a much more difficult mode to work with compared with mode 13h ([tt]SCREEN 13[/tt]), though, because the pixels are unchained, meaning that every pixel is spread across the memory planes. Fast graphics in mode X requires a lot of bit twiddling, which is something QuickBASIC is not very good at.