Switcher

A switcher or shunter (Great Britain: shunter; Australia: shunter or yard pilot; USA: switcher or switch engine, except Pennsylvania Railroad: shifter) is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been brought in, and generally moving railroad cars around – a process usually known as switching (USA) or shunting (UK). They do this in classification yards (Great Britain: marshalling yards). Switchers may also make short transfer runs and even be the only motive power on branch lines and switching and terminal railroads. The term can also be used to describe the workers operating these engines or engaged in directing shunting operations.

The typical switcher is optimised for its job, being relatively low-powered but with a high starting tractive effort for getting heavy cars rolling quickly. Switchers are geared to produce high torque but are restricted to low top speeds and have small diameter driving wheels. Switchers are rail analogs to tugboats.

Switcher (disambiguation)

Switcher may refer to:

Technology

MultiFinder

MultiFinder was the name of an extension software for the Apple Macintosh, introduced on August 11, 1987 and included with System Software 5. It added the ability to co-operatively multitask between several applications at once – a great improvement over the previous systems, which could only run one application at a time. With the advent of System 7, MultiFinder became a standard integrated part of the operating system. It remained a part of the operating system until Mac OS X.

History before the MultiFinder

The first Macintosh, released in 1984, had such limited memory (128 kB) that Apple's developers decided early on to abandon the multi-tasking that Apple had developed for the Lisa.

Desktop Accessories

To allow some degree of freedom, the original Macintosh included Desk Accessories, such as a calculator, that could be run concurrently. However, these were deliberately limited so that they would not use up too much of the available RAM. In fact, they were device drivers which took advantage of the multitasking system designed for hardware peripheral support. Although the system software did little to specifically support them, the popularity of Desk Accessories led many application developers to ensure good cooperative multitasking support even from the early days.