Solution 10607: Varying Processing Speeds of Some TI-89 Models.
Why are some TI-89 models slower than others?
TI is always looking for ways to enhance product operation while maintaining or
reducing cost for the customer. One such enhancement resulted in an increased
processing efficiency for the TI-89. There is nothing wrong with the processor
of slower models. The difference is analogous to newer computers that operate
faster because of hardware revisions, component or software improvements.