A hardware or software flag. In multitasking systems, a semaphore is a variable with a value that indicates the status of a common resource. It's used to lock the resource that is being used. A process needing the resource checks the semaphore to determine the resource's status and then decides how to proceed.
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24.99HO #H-860 MSRP $29.80 LOWER QUADRANT SEMAPHORE w/regular base 3 position square arm,1.5 Volt lamp red-red-green lens. Brand new in package Buy more th...
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12.55Recommended age group: 36 months - 7 years, Manufacturer: Brio Corp.
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19.95N Scale NJ International Semaphore Relay Base Point Blade
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39.99turbinemongoose store The Lionel 6-22944 Automatic Operating Semaphore is a great way to add realism and action to your O guage train layout. This acc...
