This Crazy Device Sends TI-83 Calculator Output to VFD Tubes

The Texas Instruments TI-83 was one of the most popular calculators of all time, and you most likely used one yourself if you were in school anytime between 1996 and 2004. The TI-83 was a graphing calculator packed with interesting features, including user programmability with the TI-BASIC language and data transfer through a 2.5mm link jack. Those facilitated some fun uses aside from simply performing calculations, such as gaming. As it turns out, that link port can be used for more than just sharing games with your friends, as proven by this crazy device that sends TI-83 Plus calculator output to be displayed on VFD tubes.

Jhoffnun was inspired to create this device by the large calculator they had in the in basement of their college. That calculator displayed calculation results on large Nixie tubes, but Jhoffnun decided to use VFD (Vacuum Fluorescent Display) tubes for this project. Those look a bit like Nixie tubes on a superficial level, but work in a completely different manner and show digits in a nice glowing blueish-green color. This device has eleven IV-6 VFD tubes that are used to display the digits output from the TI-83 Plus. It also has an additional 2x16 character LCD screen that shows the output and a bit of extra information, like the number of digits required. There is a toggle switch for power, a potentiometer knob for display brightness, a reset button, and a button to display a new result.

A Microchip PIC16F88 microcontroller is used to receive the data coming from the TI-83 Plus’s link cable using the great TI-library written by Thomas Henry. That then sends the output to both the VFD tubes through an A6812SA shift register and the LCD screen. A separate PIC12F683 microcontroller is used for a boost converter that pushes the voltage up to 20-30V to drive the VFD tubes. A single LED to the left of the VFD tubes is used as a sign to indicate if the displayed value is negative. All of those components, along with the TI-83 Plus itself, are mounted onto a simple piece of wood. The answer to a calculation on the TI-83 Plus is stored as a variable, which is then retrieved by the PIC16F88 when the new button is pressed. That is then printed to the LCD screen and converted into values to drive the segments of the VFD tubes. This device may not have any practical purpose, but it’s really cool to see how data can be pulled from a TI-83 and displayed in an interesting way.