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Vera - the Calc Lover's OS

This repository is an attempt to collect the brave repeated undertakings of several people from the TI graphing calculator scene to build their own operating system for the calculator from scratch. This project became known as "Vera". To my knowledge, three separate but loosely related attempts have been made that resulted in actual code.

My role in the first two attempts was limited (I remember I came up with the name Vera, which is nice). The third attempt was my own pet project.


If you have more files or links or know more about this than I do, please send your pull requests my way 😄

Generation 1 (early 2006)

Screenshot of Vera generation 1

There are two releases of this version, 0.0.1 (5 February 2006) and 0.0.2 (28 april 2006), as part of the "Pre Alpha" release. It actually still has a working website on sourceforge:

The central figure in this effort was probably Brazucs from the UnitedTI forums. Also, it references Jim's stuff :) in the comments at some point. That's undoubtedly "Jim e" from the forums.

The code is pretty small and has a singular purpose, but I think the real achievement lies in being able to generate a ROM file from scratch that boots on a calculator and then does anything without being able to depend on the original OS's subroutines, like outputting some text and getting some input.

Generation 2 (late 2006, early 2007)

Again, I've forgotten who put this together. But we have some actual documentation this time, which mentions a couple of people by name:

this file contains the names of the people who wrote code for Vera or whose code was stolen for Vera:
-Jim e ...
-Timendus ...
-flopus maximus, Benjamin Moody
-Jacobbus, Jacob van Ginkel
-and of course all the other people form UnitedTI
maybe I forget some add them please

sources where we ripped most of the code from:
-the API
-Pong OS
-wiki ti
-and more

I see my nickname there, although I can't seem to remember actively contributing code to this project. So that's probably just because they ripped "the API", which was a project of mine that I added lots of routines to (it was an online routines repository, the contemporary equivalent of which would be something like npm).

The ROM file doesn't seem to do very much or to be very stable, unfortunately. But still, it manages to boot the calculator and respond to keypresses, which is already quite impressive.

These's also lots of code. Clearly the author(s) tried to provide a more generic API as an abstraction of the hardware for programmers.

Generation 3 (late 2007)

Screenshot of Vera generation 3

This project was announced and discussed here:

This is the version of Vera I started. The original plan was to write it in C using sdcc, but a lack of experience with that (or rather: the abundance of experience in writing 'pure' z80) in the community made quick work of those plans.

Being in university and studying computer science, I started this project with documentation and testing in mind. So a tool was written (taking ideas from JavaDoc) to generate HTML documentation from comments in the assembly source files. The tool (although pretty crappy) has survived and can be found here. Also, we have two versions of the generated documentation website, that can be seen in the docs directory. The latest version can also be browsed through online. The screenshot above shows several "tests" that had been implemented, but there was also a pretty serious effort under way of writing a suite of automated tests. How very rigorous of young me 😄

The actual Vera source is a different story though. The code was hosted in an SVN repository that was on my private server. Somehow I can't find the code on any of my computers anymore, and the server is long gone. I'm sure it can still be recovered somewhere in the mess that is my collection of ancient PCs, but all attempts so far have failed. The only file I have is one that I copy-pasted on the Maxcoderz forum, and was able to retrieve there.

There also used to be a wiki with all kinds of info on it. That's just as lost. If only we would have had Github back in those days 🙈. What does still exist though is the Google group or mailing list with lots of interesting bits of information.

And we do have an actual running ROM file, so that's cool. The above screenshot shows off all of its features 🥳


A hobbyist Texas Instruments graphing calculator OS from the zeros