Graphing calculator games have a long, fascinating history

Ask any professor, and they’ll probably tell you graphing calculators offer a plethora of mathematical uses, like plotting graphs, inputting trigonometric functions — you know, typical academic stuff. Many students find that they offer a second feature, the possibility to play in class. It is hard to find better ways than games for skiving off. DoomAnd Portal covertly than tapping away on a graphing calculator — the school-sanctioned gaming system — as a lecturer rambles on about equations.

The history of calculator game development, which only began in earnest in the 1990s, may be recent, but it’s an eventful one. That’s because the graphing calculator is a relatively niche platform that’s not oriented around games, even if the platform has an ardent community of developers — many of whom create calculator games precisely because of the devices’ limitations.

“I mostly [got started making calculator games] because I was bored out of my mind in class and a graphing calculator was the only electronic device I was allowed to use,” says John Cesarz, a web developer who discovered the hobby through fiddling with a Texas Instruments calculator in eighth grade. “But I kept doing it because I liked the challenge involved with [the] strict hardware limitations the calculator provided.”

While Cesarz may be unfamiliar to most people, the recent successes of the Calculator games are well-known. Wordle, CelesteGoogle Chrome’s dinosaur game. Yet large communities centered around calculator games, such as ticalc.org, Cemetech, and TI-Planet, have been around since the ’90s. It was then that graphing calculators were more readily available and affordable. One of the most popular calculators among calculator enthusiasts back in those days was the TI-81. This calculator, released by Texas Instruments as the first to have a built-in scripting engine called TI-BASIC, was one of the most widely used. These allowed for very easy programs to be created.

Martin Bousquet was inspired by this gadget to become a programmer. Bousquet grew up a gamer and was intrigued when his brother gave him an RPG for the TI-81. He decided at 11 that he would like to build one. “My parents had a computer, but they were really reluctant to me trying [to make my own games] […] because I broke one of the computers and they were kind of mad at me,” he laughs. That became his first foray into programming, even though he says the TI-81’s rudimentary design rendered game development extremely tedious. “There was no way to get an input without stopping the whole program, so you can’t really make video games. […]Only one choice can be made, just like you cannot make multiple selections. There are two options. You could choose a single pixel. It’s very, very slow, [but]I wasn’t hooked. I was hooked from the start.”

Calculator game development didn’t immediately take off on the TI-81, since there was no way to transfer data to other devices, so games made were not sharable. This meant that all games were manually entered one by one. With the TI-85’s 1992 launch, all games were now able to be transferred from one calculator to the next via a serial port to other computers. What this development meant for the burgeoning calculator community was it could develop and launch games on the calculator that were created via assembly — a much more advanced programming language. Bousquet recounts one of his classmates telling him that using assembly, as opposed to TI-81’s BASIC language, would allow him to make games more effectively. As he didn’t have access to the internet at that time, Bousquet had to head to the library — where the internet was freely available — so that he could learn more about assembly online.

“Back in the ’90s we only had the BASIC language, which was very limited in speed and graphics. […] z80 assembly allowed you to take almost full control of the hardware, but had a much steeper learning curve,” says James Vernon, another calculator game developer. But one does not simply plonk a game into their TI-85 device; after all, the operating systems in these calculators weren’t made for games in the first place. As renowned calculator hackers discovered, the secret was to cleverly make use of vulnerabilities in firmware. This resulted in several assembly shells — programs that allow assembly games to run on calculators — being created by the Texas Instruments community, with the first being ZShell.

But these weren’t the only innovations that emerged from the calculator community. Programmers were also crafting libraries — prewritten code, open-source operating systems, emulators, unique languages, and other tools — so that calculator games could be developed with greater ease.

Even though Texas Instruments wasn’t the only company making graphing calculators — Casio, Sharp, Hewlett-Packard, and NumWorks were also in the mix — Texas Instruments happened to be the most popular brand among enthusiasts. The company’s popularity still persists among calculator hackers today. “The Casio calculators have a large relative French community, but most users today appear to be using TI calculators. I’ve never programmed for the Casios, but from what I’ve seen it tends to be more difficult because of the lack of support,” says developer Matt Waltz.

That said, Texas Instruments has frowned upon the community’s penchant for making games for its calculators over the years, even if some Texas Instruments engineers have been quietly impressed by the community’s efforts. In a New York Times interview from 1999, Richard Schaar, vice president at Texas Instruments, said the company wanted to see if users could figure out the devices’ proprietary assembly language, marveling when students were able to do so handily. “But then kids figured it out [on]Their own. They reverse-engineered the assembly language,” he said. At one point, the company even worked with ticalc.org to release calculator games on a CD-ROM, although that was recalled in 2001 due to parents finding “inappropriate content” on it.

With subsequent firmware patches and the release of newer models, it was clear that Texas Instruments didn’t want its calculators tampered with, ostensibly to deter cheating in class. “TI have become more resistant to the community as well, due to the fact that their biggest market is the education sector, and so teachers typically don’t like their students to either be sitting in math class, gaming on their calculators, or using software that’s intended to workaround enforced memory resets before exams,” says Vernon. This led to the company using its legal resources with impunity. The issuance of DMCA requests for the removal of hacker factors to the TI-83 Plus range in 2009 as well as the websites and forums where these keys were posted, is a prominent example. This allowed hackers to create their own operating system on the devices. Texas Instruments’ efforts were rebuffed when Electronic Frontier Foundation offered to pro-bono help for three hackers who had received DMCA notices.

Texas Instruments attempted to stop the development of calculator games in other ways, but hackers eventually managed to bypass them. “TI released an update recently that removed official support for native programming, which the majority of well-known games use. This really hasn’t affected game development that much, since an exploit was quickly found, and it pretty much just amounts to an extra installation step for the end user,” says Cesarz. Cesarz says that these were only temporary issues and developers will continue making games for calculators. A lot of people enjoy the challenge of creating games with hardware that is less powerful than modern consoles or PCs. This forces them to code more efficiently.

“Limited hardware and limited programming language are probably the main hurdles that one may encounter [when making calculator games],” says Adrien “Adriweb” Bertrand, the co-founder of TI-Planet.org, a prominent French site for Texas Instruments calculators. “If you take the good old TI-83 Plus, then you have a rather slow ancient z80 CPU, a 96 by 64 black-and-white screen, a few 10s of KBs of memory, and very limited features […]TI-BASIC. However, it’s got a bit of the ‘bare minimum’ in everything that you’d expect from being able to play good games. It can switch pixels, use the keyboard to read and do the math in the algorithms. That’s basically good enough to make a whole lot of things, even if it’s not powerful.”

Cesarz points out another peculiarity of games made for calculators, their unusual hardware architecture. “The TI-84 Plus CE uses an eZ80 processor, and is, to my knowledge, one of the only consumer devices to do so. This means that the majority of the developer tools you can use have been written by others in the calculator community as personal projects, and they often have bugs in them that haven’t been found yet because of how few people are using them,” he says. “You sometimes can’t tell whether a bug is an issue with code you wrote, code that someone else in the community wrote, or code that TI wrote, which makes debugging take longer than on other platforms.”

Image: James Vernon

Image: James Vernon

These quirks can sometimes be annoying, but they have not stopped the game developer community from developing new games. Developers are happy to recreate classic games, such as DoomAnd There are many of usVernon and others have created original calculator games that are not available on any other platform. The following title is an example. Legend of the Hellspawn: Banchorfor the TI-84 Plus CE. “[Banchor]This was the inspiration for GolvelliusSega [Master System], Zelda, and the Diablo series,” says Vernon. “I’d wanted to make a top-down RPG-style game for a while on the calculator. It seemed like a challenging genre to tackle given the limited memory that the calculators had, and I was excited by the storytelling that you can do in an RPG.”

Tinkering with calculators has also introduced developers — many of whom are students and teenagers — to the intricacies of programming. While some have degrees in computer science and others work as programmers or engineers across a variety of industries, many are still learning. Bousquet runs Blue Noise Games, an indie developer who creates PC games. They also credit their passion for programming, and the trajectory of their careers to their experience making calculator-games.

Even though calculator forums may appear dormant today — many developers from the halcyon days of calculator games in the late ’90s don’t make games anymore, and updates on these sites are less forthcoming than a decade or so ago — the community is still active in obscure corners of the internet. “It’s true that there aren’t as many posts on calculator forums as there used to be, but that’s less because there’s not as much happening lately and more because discussion has moved to less publicly visible Discord channels,” says Cesarz.

Current projects revolve around calculator games. Bertrand claims that he created a real time collaborative editor to build programs and games using C++ and C++. “I’m just so glad to see that the calculator programming community is still alive and well, [even if it’s]Mostly on TI […] and for the fact that we now have such community-made tools available today that we could have only dreamed of in the past,” he says.

Perhaps the community’s enduring presence can be seen as an obtrusive middle finger against the sterile academic ambitions of Texas Instruments, a company that continues, even in recent years, to try to one-up the community from hacking its devices. These hackers could be more like rule-breakers. The students are openly challenging the established rules of school education.

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