Late 80s to early 90s before Linux existed there weren't many ways to run unix on x86 hardware of the time. I remember desperately searching for solutions so I could have unix at home and not always rely on the university SunOS/HP-UX/AIX machines.
SCO was one player in this space. I can't remember the other one I was considering.. In the end they were all too expensive for poor-student-me so didn't use any of them and kept using the lab SunOS boxes via 2400bps dialup from home until Linux appeared on the scene.