Frankly if you replicate the TI-83's layout in a GUI, and emulate its OS, and sell it for $10 on the App Store, you'd make millions. Any student carrying around

Frankly if you replicate the TI-83's layout in a GUI, and emulate its OS, and sell it for $10 on the App Store, you'd make millions. Any student carrying around an iPhone/iPod Touch/iPad would gladly pay that, rather than $100 for a new bulky TI-83, and use that in school instead. Makes their lives simpler by only having a single device. Replicating the interface is key. From my experience, most teachers were horribly confused if someone brought in a TI-89 or, forbid, a TI-92. Why? Different UI that they don't know. You can't teach students how to use their calculator unless you know how to use it yourself. After, you can add in all sorts of extra features like you mentioned. But "A TI-83 that runs on iOS" is probably the first feature that people will pay for. It does bring up the issue of students cheating on tests, using their iOS "calculators", but last time I checked it's not too hard to hide notes on your TI-83 either... It's an idea I've had for an iOS app for a while, but don't have the time to dedicate to it (working on something else).