hundreds of incredible references online dealing with the history of computing, and especially about the TI-99/4 and TI-99/4A computers. I list as many as I can find for your reference:
* [http://www.computinghistory.org.uk/ Centre for Computing History] = This is a UK-based, general computing history website that has numerous articles involving the TI-99/4A.
* [http://www.elisoftware.org/index.php/Main_Page Eli's Software Encyclopedia] = This software focused website includes many articles about TI-99/4A software. It's written using MediaWiki (the same software as this website and Wikipedia).
* [http://www.mobygames.com Moby Games] = A general video game website that hosts several TI-99/4A game pages.
* [https://www.ninerpedia.org/wiki/Main_Page Ninerpedia] = A great resource run on Mediawiki (the same software as Wikipedia and this website).
* [http://my.stratos.net/~hewston95/RTM/RTM_Home.htm Retrogaming Times Monthly] = An archive of an older website covering multiple 1980's computing devices.
* [http://www.videogamehouse.net TI-99/4A
Videogame House] = A strictly TI-99/4A page covering many of the most popular video games for the TI-99/4A. '''One of my favorite resources'''. It hasn't been updated for a while, but neither has the TI-99/4A, so it's totally legit.