An interesting calculator made by Texas Instruments. It has a QWERTY keyboard, numeric keypad and fairly large screen, so it's extremely large by almost all calculator standards.
- MC68000 processor running at 10 MHz
- 188K RAM
- 384K Flash ROM
- 240x128 pixel mono screen
It's basically the most powerful and expensive TI calculator, at least for its time. It has a very nice OS and can do symbolic manipulation, factoring, solving, etc. easily.
That being said, it should be noted that the TI-92 and TI-89 have the same OS and software except for Cabri (correct me if I'm wrong).
In addition, they both contain the same amount of RAM and flash and have the same processor. Thus, apart from the keyboard and larger screen (240x120 vs. 160x160) there aren't many compelling reasons to get one. Heck, for the same amount of money, get yourself a nice old Pentium laptop. In addition, the calculator is banned from most formal exams, even more than the TI-89.