Yesterday, I left off talking about the TI-85, the second Texas Instruments graphing calculators.
The 85 had a huge problem, it was designed for college level calculus. It could be used to solve polynomial expressions. This was a problem for highschool algebra classes as well as the SATs. (I can't find any records of when the policy changed, but I know that initially, the TI-85 was banned from use on the SATs for this reason.)

What was TI's response? The TI-82 in 1993, less than a year after the TI-85.
This new calculator had many of the features people loved about the 85, like the ability to use the link cables, and a backup battery, but TI cut the functionality down to something closer to the 81, then cut the memory in order to bring down the price.
This made the TI-82 the most sought after calculator for highschool classrooms. It also makes it probably the most popular of all the models sold in the 90s.

The TI-82 was so successful, that Texas Instruments didn't release any upgrade for 3 years. But there were other models in the mean time.

In 1995, Texas Instfuments released 2 new graphing calculators taking the features of the previous models to the extreme.

The TI-80 was a cut down version of the original 81 but much smaller and capable of running on 2 coin-cell batteries.

The TI-92 was the biggest beast of them all sporting more pixels, more memory, and a full qwerty keyboard. It also used a Motorola 6800 processor at 10hz. So it was basically a Macintosh in your pocket.

While the 80 basically flopped, the 92 did really well despite the fact that it was banned from use on any national exams due to that keyboard. And it remains banned for that reason today. Despite that, college level calculus classes loved it due to its inclusion of CAS (Computer Algebra System, basically it can do everything you learned in Algebra). (I will definitely be talking more about this one over the weekend.)

In 1996, Texas Instruments finally released a successor to the TI-82, the TI-83.
Functionally the only changes were a much better screen (although at the same resolution) and a little more memory for programs (4k to be exact). The change that got most people to switch, was the new design of the case. Like Apple, Texas Instruments decided form was more important to consumers than function. (More on the 83 this week as well. This was my highschool baby.)

1996 also saw a small improvement in the 92 which was really just them fixing bugs in the firmware.

In 1997 a successor to the TI-85 was released. This was mostly the same as the 85, but with the same form factor as the 83 and the newer screen. (BTW, did I ever mention that the 85 had a wider screen?) But the big improvement, the new TI-86 had 128kb of memory while still using a z80 processor. (Yes, at this point in the story, the z80 is nearly 20 years old and still in use.)
The TI-86 was a huge success in colleges, (and it looks like the SAT board got over the whole polynomial equation thing by this point.) However, highschools still avoided it because they felt it allowed Algebra students to cheat on tests. So sales were not as good as TI had hoped.

In 1998 Texas Instruments released the TI-89. This was nearly identical to the 92, but in the same form factor as the 83, and 86. This new model nearly killed the 86. For only $10 more, it had 2x the memory, higher resolution, faster processor, CAS, and it was allowed for use on the SATs. Again, highschools avoided it, but by this point every college student had grown up using graphing calculators and colleges were dependent on them.

Also in 1998, a few revisions were made to the TI-83 and some new cheaper calculators were released. The TI-83 Plus was the last model released in the 90s and ends our history here.

To date, according to Texas Instruments, the TI-84 Plus, released in 2004 and still available today, has been the best selling of any model. But, there is nothing retro about something you can still buy brand new at Walmart.

All of these calculators, except the 83, were purchased from local thrift stores for less than $5 each since Lunduke announced handheld week.