Changes
* there are zero interrupt sources in an unexpanded machine. There is no way to keep track of time other than processor cycle counting.
The original machine was followed up by the II+, which includes a better BASIC and can automatically boot from a disk drive if attached, the IIe and IIc, both of which offer up to 128kb of RAM, 80-column text and a higher-density pixel graphics mode, and the IIgs, a 16-bit 65816 backwards-compatible machine with a Macintosh-modelled OS.
All machines use a keyboard that cannot communicate multiple simultaneous keypresses, which makes playing games by keyboard difficult. The II and II+ also lack the capacity for lowercase text entry and cannot display lowercase letters in their clean text mode. However all generations of machine have analogue and trigger inputs, which are most commonly used for two two-axis analogue joysticks with two buttons, accepted by the majority of games.
The Apple IIc is the fourth model in the Apple II series. It was introduced shortly after the launch of the original Macintosh in 1984. The c in the name stands for compact. It is essentially a remarkably compact version of the Apple IIe. The IIc has a built-in floppy disk drive, and was often sold with its matching monitor.
The IIgs is the final model in the Apple II series, equipped with a backwards-compatible 16-bit 65816 CPU with a Macintosh-modelled OS.
==Audio==
