Search results
Results from the WOW.Com Content Network
Semaphore (lit. ' apparatus for signalling '; from Ancient Greek σῆμα (sêma) 'mark, sign, token' and Greek -φόρος (-phóros) 'bearer, carrier') [1] is the use of an apparatus to create a visual signal transmitted over distance. [2] [3] A semaphore can be performed with devices including: fire, lights, flags, sunlight, and moving arms.
Semaphores are signalling mechanisms which can allow one or more threads/processors to access a section. A Semaphore has a flag which has a certain fixed value associated with it and each time a thread wishes to access the section, it decrements the flag. Similarly, when the thread leaves the section, the flag is incremented.
A replica of a Chappe telegraph tower (18th century). A 'semaphore telegraph', also called a 'semaphore line', 'optical telegraph', 'shutter telegraph chain', 'Chappe telegraph', or 'Napoleonic semaphore', is a system used for conveying information by means of visual signals, using towers with pivoting arms or shutters, also known as blades or paddles.
A system like flag semaphore, with an alphabetic code, can certainly send any given message, but the system is designed for short-range communication between two persons. An engine order telegraph , used to send instructions from the bridge of a ship to the engine room, fails to meet both criteria; it has a limited distance and very simple ...
A hydraulic telegraph (Greek: υδραυλικός τηλέγραφος) refers to two different semaphore systems involving the use of water-based mechanisms as a telegraph. The earliest one was developed in 4th-century BC Greece, while the other was developed in 19th-century AD Britain.
German semaphore home signals, which are totally different in appearance to the British semaphore signal, include one or two white arms with a red outline and a small circular disk at the end of it, and coloured lenses which display the position of the aspect(s) of the signal during nighttime operation and these arms face right of the post.
Explicit communication can be divided into two classes: Shared memory communication Concurrent components communicate by altering the contents of shared memory locations (exemplified by Java and C#). This style of concurrent programming usually needs the use of some form of locking (e.g., mutexes, semaphores, or monitors) to coordinate between ...
The original semaphore bounded buffer solution was written in ALGOL style. The buffer can store N portions or elements. The "number of queueing portions" semaphore counts the filled locations in the buffer, the "number of empty positions" semaphore counts the empty locations in the buffer and the semaphore "buffer manipulation" works as mutex for the buffer put and get operations.