To return a numeric value that is the ASCII code for the first character of the string x$.
If x$ is null, an "Illegal Function Call" error is returned.
If x$ begins with an uppercase letter, the value returned will be within the range of 65 to 90.
If x$ begins with a lowercase letter, the range is 97 to 122.
Numbers 0 to 9 return 48 to 57, sequentially.
See the CHR$ function for ASCII-to-string conversion.
See Appendix C in the GW-BASIC User's Guide for ASCII codes.
10 X$="TEN" 20 PRINT ASC(X$) RUN 84
84 is the ASCII code for the letter T.