The Atari "MicroBox"

The "MicroBox" was to be the replacement for the Atari Falcon computer. Enhancements were to include new case design (Sun-like) and a true 32-bit bus with three 32-bit expansion slots. An upgrade-option to the Motorola 68040 processor was considered.
Atari had several prototypes of the MicroBox, but the memory controller was buggy. Just before the release date, Atari left the home-computer business and focussed its efforts on its new home-video-game system, the "Jaguar 64". The MicroBox was never released.