The unit features a 160×100 pixel resolution LCD and a large amount of flash memory, and includes TI's Advanced Mathematics Software.

The RAM and Flash ROM are used to store expressions, variables, programs, text files, and lists.

It was created partially in response to the fact that while calculators are allowed on many standardized tests, the TI-92 was not due to the QWERTY layout of its keyboard.

The major advantage of the TI-89 over other TI calculators is its built-in computer algebra system, or CAS.

The TI-89 is directly programmable in a language called TI-BASIC 89, TI's derivative of BASIC for calculators.

In addition, there is a third party flash application called GTC that allows the writing and compilation of C programs directly on the calculator.

In HW1 calculators there is a video buffer that stores all of the information that should be displayed on the screen, and every time the screen is refreshed the calculator accesses this buffer and flushes it to the display (direct memory access).

This allows for slightly faster memory access, as the HW1's DMA controller used about 10% of the bus bandwidth.

However, it interferes with a trick some programs use to implement grayscale graphics by rapidly switching between two or more displays (page-flipping).

On the HW1, the DMA controller's base address can be changed (a single write into a memory-mapped hardware register) and the screen will automatically use a new section of memory at the beginning of the next frame.

It is believed that TI increased the speed of HW4 calculators to 16 MHz, though many users disagree about this finding.

The TI-89 Titanium also features some pre-loaded applications, such as "CellSheet", a spreadsheet program also offered with other TI calculators.

The Titanium has a slightly updated CAS, which adds a few more mathematical functions, most notably implicit differentiation.

Some have to be recompiled to work on the Titanium due to various small hardware changes, though in most cases the problems can be fixed by using a utility such as GhostBuster, by Olivier Armand and Kevin Kofler.

In some cases, only one character needs to be changed (the ROM base on TI-89 is at 0x200000, whereas the TI-89 Titanium is at 0x800000) by hand or by patcher.

Most, if not all, of these problems are caused by the mirror memory (ghost space) or lack thereof.

The TI-92 series, with otherwise comparable features, has a QWERTY keyboard that results in it being classified as a computer device rather than as a calculator.