Mockingboard

The Mockingboard (a pun on "Mockingbird") is a sound card for the Apple II series of microcomputers built by Sweet Micro Systems, which improve on the Apple II's limited sound capabilities.
In 1981, Sweet Micro Systems began designing products not only for creating music, but speech and general sound effects as well, culminating in the release of the Mockingboard in 1983. The Mockingboard's hardware allowed programmers to create complex, high-quality sound without need for constant CPU attention. The Mockingboard could be connected to the Apple's built-in speaker or to external speakers. However, as the quality of the built-in speaker was not high, the instruction manual recommended obtaining external speakers.
The Mockingboard was available in various models for either the slot-based Apple II / Apple II Plus / Apple IIe systems or in one special model for the Apple IIc. Sound was generated through one or more AY-3-8910 or compatible sound chips, with one chip offering three square-wave synthesis channels. The boards could also be equipped with an optional speech chip (a Votrax SC-01 or compatible).
Some software products supported more than one Mockingboard. "Ultima V" supported two boards, for a total of 12 voices, of which it used eight. Most other programs supported at most one board with six voices.
Applied Engineering's Phasor was compatible with the Mockingboard. It had 4 sound chips and thus provided 12 audio channels. Few programs supported using it for more than six voices, however.
An IBM PC-compatible version was developed, but was only distributed with Bank Street Music Writer.