The first known arcade emulation available publicly was the Williams Digital Arcade series from Digital Eclipse Software, released for the Macintosh in 1994. This series featured the Williams Electronics' arcade classics Joust, Defender and Robotron: 2084. In 1995, it was repackaged and expanded upon as Williams Arcade Classics for the PC. For these games, Digital Eclipse developed an interpreter that emulated the games' arcade machines' chipset, including the Motorola 6809 central processing unit. This approach was meant to have the emulations act true to the original versions of these games, and not carry any imperfections direct ports could have introduced.