The TI-84 came out in 2004 which I have a hard time calling Stone Age for anything calculator related, graphing or otherwise. But if you were born in 2000 or so

The TI-84 came out in 2004 which I have a hard time calling Stone Age for anything calculator related, graphing or otherwise. But if you were born in 2000 or so perhaps it feels that way. This is also getting well past the time calculators were marketed heavily outside the education market anyway. Also the 84 really is an enhanced 83 which is solidly targeted as a secondary education machine. TI would even sell them etched with “School Property” https://brownmath.com/ti83/diff8384.htm#Catalog https://brownmath.com/ti83/diff8384.htm#Catalog In the Stone Age of graphing calculators (80s-90s), HP was dominant in engineering disciplines (and France). Now I think maybe you’re confusing with the TI-85 (but the TI-86 was a TI-85 replacement and handles matrices just fine and superior to the 84) - so then perhaps your teacher had a TI-83. That would be more plausible and sensible.