get a new one
The TI-83 has a very good screen and excellent graphics.
-2
The TI-83 series was released in 1996.
No, in order to download apps to your TI-83, you need a cable that connects your calculator and the computer, or a cable to connect to another TI-83.
Yes
The TI-84 is a graphing calculater. It is mostly just an update to the TI-83 calculater.
"http://wiki.answers.com/Q/How_do_you_put_games_on_the_TI-83"
Some of the features of the TI-83 Plus, are: upgradable operating system and software; preloaded apps; compatible with TI-84 Plus and TI-84 Plus Silver Edition.
There isn't a sec key on the TI-83 Plus. Secant is 1/cosine, which is what is used to find secant on a TI-83 Plus. For example, to find the secant of 4, enter 1/sec(4).
Yes, it keeps tracks of the keystrokes until you clear the screen.
graphing calculators only. TI-83 and TI-84 calculators.
There is not cos2 button on a TI-83 plus. You will need to enter the cosine function and then square it. (Press the x2 button to get the squared function.) To type cos2(90) on a TI-83 plus, for example, type: cos(90)2