Well, good old PC speaker is the only default hardware, easily available on almost all PC systems, and virtually unmuteable (actually, one can connect PC speaker output to his/her sound card instead of default buzzer, but this rarely happens . Thus, it is perfect for communicating critical states. But the default system beep is quite boring, and makes difficult to distinguish different events that are being communicated. So, here's my humble attempt to make a highly portable function that is able to play simple non-polyphonic music on the PC speaker. I used it originally to advise when someone tried to log in to my system through SSH daemon (thus the name "daemoniac" - demoniac . It was tested (and worked fine!) under:

• DOS (DJGPP, Turbo C)
• Windows 9x/NT/2K/XP (Borland C, Microsoft Visual C, MinGW)
• Linux (gcc)
• FreeBSD (gcc)

By default, demoniac will play Iron Maiden - Fear Of The Dark beginning. You can also compile it to play the simple "A#4 D#5 G5 A#5 G5 A#5" melody. Note that on UN*X systems, demoniac accesses hardware directly, and thus requires to run as root user. It's safe, through: it won't accept any command line arguments and neither process environment variables, so, at least, it can't be exploited with some buffer overflow technique. For detailed instructions about compiling demoniac on different compilers/systems, read the comments at the start of the source. Note that my package provides all the binaries generated on compilers/systems listed above.