Mockingboard

The sound card Mockingboard ( pun on the English word " mockingbird" - Mockingbird ) was an expansion card company Sweet Microsystems, for the home computer Apple II or Apple IIc and one of the world's first sound card for home at all. It was sold in different versions; the standard version offered six-part sound synthesis and could be upgraded to a speech synthesis extension.

The Apple II disposal of house are very limited options for sound output. His sound interface consisted of a built-in speaker, the membrane could be informed by software access to a given hardware address between two spatial positions back and forth - essentially equivalent to that of a more primitive version of the later IBM PC system speaker. About suitable programs of this output could be switched to the desired frequencies and so spend tones. However, the Apple II had no programmable frequency generators, timers or interrupt, the CPU therefore had to take care of the entire tone - what sound programs made ​​very complicated and the execution of other tasks ( such as changing the screen contents shown) during a sound practically prevented.

Hardware

The Mockingboard based on the sound chip AY -3- 8910 who brought three independent generators and a tunable square wave noise generator. This chip was in the 1980s and later used in many game consoles in the Atari ST so that a Mockingboard in the basic equipment provided a similar sound. Was Adjusts the sound chip on the interface chip VIA 6522, nachrüstete the same time the lack of the Apple II and timer interrupt sources. A 0.5 W output amplifier for connection to an 8 -ohm speakers completed the circuit.

Variants of the " Mockingboards " brought more than a sound chip and also provided an option to retrofit the speech synthesis chip Votrax SC -01. Later, the largely compatible chip variant SC- 223 was used.