My first company out of uni was a company that sold a tv advertising application written in dos. It did all the reports, put together spot advert packages, measuring reach and frequency, cost per point, etc. Used Neilsen ratings for data. The company at the time paid commissions along with salary to programmers. The app still lives on in windows, but I've been out of that game for decades. Written in TP for dos, then Delphi for windows.