> So, why aren't they just phone apps these days? Some are: https://play.google.com/store/apps/details?id=com.hp.hp15c15&hl=en https://play.google.com/store/ap

> So, why aren't they just phone apps these days? Some are: https://play.google.com/store/apps/details?id=com.hp.hp15c15&hl=en https://play.google.com/store/apps/details?id=com.hp.hp15c15... But the "magic" with the TI-84 series was not the calculator itself. It was TI's excellent marketing where (nearly) every school district, plus the SAT group, were all convinced that this particular calculator was "ok" and all others were "not ok". With the end result of a guaranteed market for TI for this calculator, without having to compete with any other manufacturers. I.e., they (TI) managed to create a 'legal' monopoly by convincing the govt. agencies to only allow this one calculator in class and during tests.