The most popular graphing calculators were of course the TI-83/84 Plus, which every American student for the past decade and a half has probably seen. Needless to say, this is the very definition of a constrained environment.

On the models with flash, support for launching large “apps” stored exclusively in flash.

TI’s operating system “TI-OS” (they call it “EOS” but nobody else does).

Generally, 32KB of RAM, and on the 83+ and later, anywhere from 100KB to 2MB of flash storage (“archive”).

A link port which (ab)used the 2.5mm headphone jack connector.

The latest models finally have higher resolution color screens.)

96圆4 black and white LCD (a few models had a larger screen but this was by far the most common.

z80 processor usually clocked at 8 or 10MHz-and note that the z80 can only retire one instruction every 4 cycles.

They were quite nice 45 years ago when they were released!Īll TI calculators generally had similar low-end specs: You might have heard of the z80-it was an improved version of the Intel 8080 developed by Zilog. Throughout the 90s and 2000s, TI released a succession of z80-based graphing calculators. I do plan to continue the articles I’ve started! Thanks to everyone who has emailed to check on me-and I apologize for not being super responsive over email. In the space of a year I’ve gotten a new job, bought a house, moved. Wow, it’s been a while since I’ve written anything. This is not a coincidence because nothing is ever a coincidence with xkcd. There are also 768 bytes in the RAM buffer used to hold TI display bitmaps. I’ll take you through some of the highlights of Texas Instruments calculator hacking done over the past two and a half decades, along with an explanation of why these projects are so technically impressive. True to my interests, it’s all deeply embedded, pushing the limits of platforms that were obsolete when they were released. There was in fact a thriving scene of hackers who had bent these calculators to their will, writing games, math software, and more generally hacking on the platform just for the sake of it. You may be surprised to learn that some of these people didn’t exist totally in a vaccuum. The one who could put games on your graphing calculator. In the mid-to-late 2000s, you either knew, or were, that kid in grade school.

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