Stephan’s recent post about the collection of micros going to the CHM reminded me of something…
A while back a series of events led me to find that the original computer that was used to create the “attacking the Death Star will not be easy” animation in the original Star Wars was, at the time, sitting in a warehouse in Chicago. The machine still has the original tapes, removable disk, and the VG terminal that drew the graphics.
I wrote to the CHM and they expressed their interest, but never followed up and I lost the trail.
This was a very interesting effort. The VG was basically a ALU, saving money by holding the 3D points and instructions to connect them in the host machine’s memory and then using DMA to access them. You would store the data in the host, in this case a PDP-11, and then send it commands to draw it. It had hardware to do rotations and scales internally, so you could send simple control sequences to have it rotate and zoom, which you can see in the movie.
The terminal also had a lamp that you could turn on or off with another sequence. They wired a single-step animation camera to the lamp, sent a command sequence to set up the next shot, then lit the lamp to make a single frame. They repeated this for all of the frames, and the compete sequence took 24 hours.
You’ll notice two different animations in the film. The first is a view of the Death Star as a whole, which zooms in and rotates. This was done entirely inside the VG. A second sequence shows the trench, which at first is similar in that you see a top-down view zooming in. After that you are “in” the trench flying along it. This was done by zooming in on existing geometry to make it “move toward” you, then removing the frontmost section and adding a new one at the back. You can see this sort of “snapping” as the new sections swap in.
I’d say this makes it one of the most historically important PDP-11s, especially as they still have the original software, and if anyone knows someone at the CHM and might be able to light a fire under their butt I think this would be a good effort!