This program will set the screen display for a TI-81 into integer mode, just as if you had typed [ZOOM][8].
It allows you to select the coordinate to be centered on the sceen, and scale the screen by the amount inputted into theta (¯).
The symbol for storage used in this proram is "->".  Do not confuse it with "Minus" followed by "Greater-Than".

Prgm:INT.Z¯¯M
:ClrHome
:Disp "INT Z¯¯M"
:Input ¯
:Disp "X-COORD."
:Input X
:Disp "Y-COORD."
:Input Y
:-4.8¯+X->Xmin
:4.7¯+X->Xmax
:¯->Xscl
:-3.2¯+Y->Ymin
:3.1¯+Y->Ymax
:¯->Yscl
:DispGraph