The Citizen 8203A watch movement is a mechanical movement that was introduced in 1965. It features a micro rotor and a double excenter regulator for curb pins and stud carrier. The movement includes a self-winding gear with direction switching facilitated by a pinion floating between two large jewels. The minute and second indicators are indirectly driven, allowing for a low profile. Since 1966/67, there have been minor modifications to the base plate and a simplified date driver. The movement incorporates several functions, including automatic winding, a sweep second hand, and a date function that can be set by changing 23-24 hours. From around 1966/67, the date can be set by changing 22-24 hours. The Citizen 8203A movement has been in use since its introduction in 1965.