My neighbor back in the 80s worked a route for the local convenience store chain when they were also doing the video rental business in store. They used a custom shaped metal computer box that was mostly rectangular in shape, but with a wedged front, containing an embedded 80x20 (or 40x20) character LCD screen.
Not too long ago I picked up a 35mm movie projector (like from a theater.) After looking into all the things I need to make it go, I started digging into the audio hardware. There are three digital standards of encoding digital audio on motion pictures. One is Dolbu Digital, which optically reads what looks like a QR oode printed between sprocket holes. Another is Sony SDDS which reads optical digital data left of the sprocket holes and on the right of the film. Finally there is DTS. DTS just has a time code dot pattern and serial number. From what I read, the decoder box uses CDs or DVDs that contain the audio. From what I have read the discs are just MS-DOS boot CDs that contain the executable that checks the serial number when it goes by and then chases the time code dot pattern with the however many channel digital sound. I guess these were used up until 2012. I don't have any DTS stuff yet. Can't get the Dolby Digital stuff I have working yet. Was surprised to hear it was MS-DOS and existed in the market that late. - Ethan