A semi-automatic transmission is a multiple-speed transmission where part of its operation is automated (typically the actuation of the clutch), but the driver's input is still required to launch the vehicle from a standstill and to manually change gears. Semi-automatic transmissions were almost exclusively used in motorcycles and are based on conventional manual transmissions or sequential manual transmissions, but use an automatic clutch system. But some semi-automatic transmissions have also been based on standard hydraulic automatic transmissions with torque converters and planetary gearsets. Names for specific types of semi-automatic transmissions include clutchless manual, auto-manual, auto-clutch manual, and paddle-shift transmissions. These systems facilitate gear shifts for the driver by operating the clutch system automatically, usually via switches that trigger an actuator or servo, while still requiring the driver to manually shift gears. This contrasts with a preselector gearbox, in which the driver operates the clutch and selects the next gear ratio, but the gear change within the transmission is performed automatically. The first usage of semi-automatic transmissions was in automobiles, increasing in popularity in the mid-1930s when they were offered by several American car manufacturers. Less common than traditional hydraulic automatic transmissions, semi-automatic transmissions have nonetheless been made available on various car and motorcycle models and have remained in production throughout the 21st century. Semi-automatic transmissions with paddle shift operation have been used in various racing cars, and were first introduced to control the electro-hydraulic gear shift mechanism of the Ferrari 640 Formula One car in 1989. These systems are currently used on a variety of top-tier racing car classes; including Formula One, IndyCar, and touring car racing. Other applications include motorcycles, trucks, buses, and railway vehicles. Design and operation Semi-automatics facilitate easier gear shifts by removing the need to depress a clutch pedal or lever at the same time as changing gears. Depending on the mechanical build, design, and age of the vehicle, they can use anything from hydraulic, pneumatic or electric actuators, electrical switches, motors, and processors, or a combination of any such systems, to execute gear shifts on demand when requested by the driver, which is typically initiated when the driver moves the gear stick. Most cars that have a semi-automatic transmission are not fitted with a standard clutch pedal since the clutch is remotely controlled. Similarly, most motorcycles with a semi-automatic transmission are not fitted with a conventional clutch lever on the handlebar. Clutchless manual transmissions Most