Click above to get retro games delivered to your door ever month!

  To begin with, you have to write your program using the commands and
  syntax of your programming language. This form of the program is known as
  the source code. For programming languages that use the standard DOS
  conventions, the source code must be in the form of an ASCII text file.
  (See Appendix C.) Interpreted BASIC does not normally use the ASCII text
  file format for its source files, but it can. (To create ASCII text files
  with the BASIC interpreter, use the A option of the SAVE command.)

  By convention, source-code files have a filename extension that reflects
  the name of the programming language used, such as BAS or C.