Changes

Although the base machine has only a simple binary toggle speaker, all versions of the machine other than the IIc provide expansion slots, allowing a large number of audio options to emerge. Of those, the Mockingboard has the best game support. Various configurations of the Mockingboard were available with different combinations of [[AY]]-3-8910 and speech synthesiser chips, connected via 6522s which also provide timed interrupt sources for the CPU. The best-supported configuration carries two AY-3-8910s and two 6522s.