When you consider the state of computers back in 1977 from our point of view here in 2009, it sometimes seems miraculous that computer-generated images made it into movies back then. We can push a button these days to easily create simple images and special effects, but back in the 1970s it was laborious just to generate a wireframe model of the Death Star. Compare that to what a comparatively simple computer system can bang out for a low-budget movie these days, and it's an extremely stark contrast.
In the video after the break, you can watch the Trench Run graphics being created for Star Wars, and computer artist Larry Cuba narrates the process. Word of warning: it's an extremely dry video, and someone had the crazy idea to throw sounds from the movie behind his narration. Sure, it takes a bit of movie magic out of the Lucasfilm mystique, but seeing those X-Wing fighters being created with digital light pens is pure nostalgia.