Teardown Tuesday: Graphing Calculator

Calculators have come a long way in the last 40 years. Once reserved for bankers, scientists, and engineers, calculators are now used by students everywhere. In 2014, 1.6 million graphing calculators were sold; but over the last two decades, there has not been much change in graphing calculators.
Recently, TI released their TI-Nspire line of calculators that offer a backlit color screen, a rechargeable battery, and extra features.
In this Teardown Tuesday, we are going to look at the insides of one of these new calculators, the TI-Nspire CX CAS. There are many different versions of the hardware: The motherboard version in this teardown is the Firebird_Color_MB_6422, the dock board version is Firebird_Color_BTB_EVT1.2_2412, and the keypad version is Firebird_Color_KB_EVT_4421.

Opening it Up

One of the 0.75mm clutch screws 

This calculator is pretty difficult to open. Up there are many screws holding the plastic shell together. These screws are several different sizes of Phillips screws, several Torx screws, and a relatively rare type of security screws called a clutch screw. The clutch screws are extremely small and require a bit with a 0.75mm blade.

Circuit Boards

The main PCB in the TI-Nspire CX CAS calculator

There are two primary circuit boards inside of the calculator. There is a third, minor board that is soldered to the keyboard PCB. There is a motherboard PCB that contains nearly all of the electronics. Located on this board are the CPU, memory, connectors, and power supply.

The keyboard circuit board

The other primary PCB is for the keyboard. On this PCB, there are 71 dome switches, a battery connector, and the PCB for the dock connector.

The dock connector PCB

Display

The LCD display in the calculator

The TI-Nspire CX was one of the first TI calculators to contain a color display. The TI-Nspire CX has a 3.2” display that contains 320×240 pixels. The display is mounted with foam to increase its ability to withstand shock. The display is manufactured by Giantplus part GPM1168.

Battery

The li-ion battery that powers the calculator 

Unlike many of today's electronics, the TI-Nspire CX has a user replaceable battery. The battery used in this calculator is a single cell lithium-ion battery that has a capacity of 1060mAh. This battery provides enough power for the device to run for weeks and have a standby time of several months. Replacement batteries are available from Texas Instruments for $10.

Keypad

Numerous dome switches on the keyboard PCB

For user input, the calculator has a touch-sensitive trackpad and 71 keys. The keys are located on a secondary circuit board that primarily contains the dome switches for the keys.
The trackpad is a separate module manufactured by Synaptics Touchpad. The module contains the part number 920-1519-1R1 and silkscreen marking indicating that it is a Synaptics part.

The PCB in the trackpad  

Processor

The processor in the calculator 

The brains of the TI-Nspire CX CAS is an ARM9-based CPU. The ARM9-based CPU has a clock speed of 132MHz and has markings of NS2010B and T6UJ1XBG-0002. The only information that is widely available about this IC is referencing this calculator, so it is most likely exclusive to it.

Memory

The Samsung NAND memory IC

Based on the hardware revision of the calculator, TI has used different NAND memory ICs. These memory ICs are manufactured by either Samsung or ESMT. In this hardware version, a Samsung K511F12ACA-B075 NAND memory IC is used.

Wrapping it Up!

The design of this calculator is a big departure from previous calculators such as the TI-84. With a color display, cursor, and rechargeable battery, the TI-Nspire line of calculators has a more modern design. Once reserved for professionals, calculators like these are marketed more towards students.