I have written similar program years ago which play beeping tones from PC speaker. Since sound cards are ubiquitous, I thought I will never use it again. Apparently, I need this program again to play some silly tones after a PC is booted up succesfully. This is because the file server PC that I have configured has no sound card. And it is a slow PC, I need to know exactly when the PC is fully booted up and I can start accessing the PC. I put this program in the Start Up folder.
The source file is beep.c