prgmBTWNSCOR
Line  Commands or Statements  Comments
   1.  ClrHome  Clear Screen
   2.  Input "x1 =",A  
   3.  Input "x2 =",B  
   4.  Input "x =",M  
   5.  Input "SD =",S  
   6.  normalcdf(A,B,M,S)->Z  
   7.  Disp"Z ="  
   8.  Disp Z  
   9.  Pause  
 10.  ClrHome  Clear Screen
Reference:
The normalcdf( Command
http://tibasicdev.wikidot.com/normalcdf
Using the TI-83 instead of the normal table to calculate probabilities corresponding to z-scores
http://wind.cc.whecn.edu/~pwildman/statnew/new_page_17.htm