This went pretty well. You can see from the video above the laser calculations are performed over several frames. However whilst this suits the Vectrex it's not accurate since it's not observing the speed of light!
The second video shows a close up of some debug counters. From top to bottom they show, frames taken to render, vectors rendered, beams processed. The good news is that they start counting but the laser doesn't appear until the end. (which is what we wanted.) The thresholds are all parametrised and the frame rate doesn't get affected when the beams are calculated. The only offset is that the sun needs to be a little higher in the sky for the beams to fire, and I think that's a nice side effect!
It all went smoothly today, which is lucky since there were several distractions. However I've firmed the code up for B1 to select object. B2 (held) enables J1 to move an object, or when released J1X rotates it. This has taken me to a junction to ponder on the game design. (I'll keep my ideas until next time though! ;)