9 track tapes were magnetic storage devices that were used in the 60s beginning with the IBM 360 mainframe. By the end of the 20th century, they became obsolete. The cloud-generation of engineers may not be familiar with such devices unless they saw them at the Computer History Museum in San Francisco or occasionally on eBay. I managed to get one from Bulgaria so as to accompany the IBM vacuum tube that I got recently for my vintage computing collection.