Overview

When the first personal computers (PC) were introduced in the late 1970's, they had very limited sound capabilities if they had any at all. As an example, the Apple II released in 1977 came standard with a simple speaker that could be toggled between two positions via software. To produce any sort of tone, a subroutine had to be written that would toggle the speaker at the de-sired frequency. The resulting motion generated monophonic square wave sound.

At the time, cassette tapes and long-playing (LP) records were the popular consumer audio formats. These formats provided audio fidelity that far exceeded that of the contemporary computers.

The sound capabilities of the computers improved over time. In 1981, Commodore introduced the VIC-20 computer, the first PC model to exceed a million units shipped. It offered three square wave generators that could be run simultaneously. Each generator spanned three octaves, but was limited to producing 128 different tones. The VIC-20 also included a white noise generator that could be combined with the square wave generators.

Launched in 1981, the IBM PC (Model 5150) was the first in a long-lived species of computers based on Intel processors that survives to this day. The IBM PC sported a single-channel square wave generator using the 8253 timer chip that was present on every system. The resulting sound has come to be known as PC Speaker or PC Beep.

By 1987, IBM had introduced multiple successors to the original IBM PC. Furthermore, compatible IBM clones...