“original IBM PC contained an Intel 8254 programmable interval timer chip to manage system clock. Because IBM engineers felt that PC needed to be able to play sound, they decided to use 8254 as a very primitive square wave generator. They programmed 3rd timer on the chip to operate in Square Wave mode and to count down with desired output frequency. This caused Out2 line on the chip to toggle from high to low every time clock went to 0. The hardware designers tied Out2 line on the chip to PC speaker and voila – they were able to use clock chip to program the PC speaker to make a Beep”. Now, in Windows 7 64–bit, PC Speaker beep is gone. Ironically, server admins are some of the people wishing PC speakers and the Beep function would be restored to help find machines in server farms. Larry Osterman explains why and it's an interesting story of how we couldn't get rid of the beep when we wanted to, but eventually changed in a round about way because of servers.
Full Article: What’s up with the Beep driver in Windows 7?