TI83 Plus Window Editor Variables in Parametric Mode
With the Window editor on the TI83 Plus calculator in Parametric mode, you must set several variables when graphing parametric equations. The following gives an explanation of the variables that you must set in this editor:

Tmin: This setting contains the first value of the independent variable (parameter) T that the calculator will use to evaluate all parametric equations in the Y= editor. It can be set equal to any real number.

Tmax: This setting contains the largest value of the independent variable (parameter) T that you want the calculator to use to evaluate all parametric equations in the Y= editor. It can be set equal to any real number.

Tstep: This setting tells the calculator how to increment the independent variable T as it evaluates the parametric equations in the Y= editor and graphs the corresponding points.
Tstep must be a positive real number.
You want Tstep to be a small number like 0.1 or
but you don’t want it to be too small like 0.001. If Tstep is too small, it will take a few minutes for the calculator to produce the graph. And if Tstep is a large number like 1, the calculator may not graph enough points to show you the true shape of the curve.
If it’s taking a long time for the calculator to graph your parametric equations, and this causes you to regret that very small number you placed in Tstep, press [ON] to terminate the graphing process. You can then go back to the Window editor and adjust the Tstep setting.
When graphing parametric equations that use trigonometric functions in their definition, it’s best to set Tmin, Tmax, and Tstep to multiples of
Tmax is set equal to
and Tstep is set equal to
is entered into the calculator by pressing [2nd][^].
The remaining items in the Window editor deal with setting a viewing window for the graph.