Problem Statement

Make the terminal running the program ring its "bell".

On modern terminal emulators, this may be done by playing some other sound which might or might not be configurable, or by flashing the title bar or inverting the colors of the screen, but was classically a physical bell within the terminal.   It is usually used to indicate a problem where a wrong character has been typed. In most terminals, if the   Bell character   (ASCII code 7,   \a in C)   is printed by the program, it will cause the terminal to ring its bell.   This is a function of the terminal, and is independent of the programming language of the program, other than the ability to print a particular character to standard out.

Let's start with the solution:

PROC Wait(BYTE frames)
  BYTE RTCLOK=$14
  frames==+RTCLOK
  WHILE frames#RTCLOK DO OD
RETURN

PROC Main()
  BYTE
    i,n=[3],
    CH=$02FC ;Internal hardware value for last key pressed

  PrintF("Press any key to hear %B bells...",n)
  DO UNTIL CH#$FF OD
  CH=$FF

  FOR i=1 TO n
  DO
    Put(253) ;buzzer
    Wait(20)
  OD
  Wait(100)
RETURN