All SGIs support the older STR_RECT stereo format. This format
interleaves the upper and lower halves of a 1280x1024 frame buffer at 120Hz.
The left eye image is drawn in the upper half of the screen, and the right eye
image is drawn in the lower half. Each half is 1280x492 pixels (there is a 40 line dead
zone in the middle, for the vertical retrace).
Newer high-end SGIs - RE2, IR, Impact, and Octane - also support quadbuffered stereo. In this method, GL maintains separate buffers for the left and right eye views; the video format alternates between the two buffers. On the RE2, the video format for quadbuffering is 1025x768_96s. On the Impact and Octane, it is 1024x768_96s. On the IR, there are several formats possible, including 1024x768_96s, 1280x1024_96s, and 1280x1024_120s.