Talk to a Texas Instruments Calculator


Texas Instruments is a world-class semiconductor company, but unfortunately what they’re best known to the general public for is outdated consumer-grade calculators thanks to entrenched standardized testing. These testing standards are so entrenched, in fact, that TI hasn’t had to update the hardware in these calculators since the early ’90s. They still run their code on a Z80 microcontroller, but [Ben Heck] found himself in possession of a which contains a modern ARM coprocessor and can therefore run Python.

Although he doesn’t know exactly which implementation of Python the calculator is running, he tore it apart to try to figure out as much as he could about what this machine does. The immediately noticeable difference is the ARM coprocessor which is not present in other graphing calculators. After some research on the test points, [Ben] found that the Z80 and ARM chips communicated with each other over twin serial lines using a very “janky” interface. Jankiness aside, finally [Ben] was able to wire up a port on the side of the calculator that allows him to use his computer to send Python commands to the device when in Python programming mode.

While there are probably limited use cases for 1980s calculators to run Python programs, we can at least commend TI for trying to modernize within its self-built standardized test prison. Maybe that’s the starting point for someone else to find something more useful for using these machines beyond the classroom. We’ve already seen some TI-84s that have been modified to connect to the Internet, for example.

Thanks to [Nikša] for the tip!


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