Calculators now emulated at Internet Archive
TI-89 basically saved my ass in collage. Not only that, I was the fourth "best student" in collage based on grade average. I modded the firmware so I was able to upload text docs organised in folders. Text filed had TOC, that made navigation easier. I was also able to search within those files.If you became fluent using all features of TI-89 (integration, derivation, diff. eqs., shortcut keys etc.) and you had a solid abstract understanding of the subject (which of course required some studying), TI-89 basically got the rest of the job done in minutes. TI-89 was magic.