context1: If there is only one such resource, a binary semaphore is used as a simple true/false flag. The P operation wastes time or sleeps until a resource controlled by the semaphore <strong>becomes</strong> available, at which time the resource is immediately claimed. The V operation is the inverse: it <strong>makes</strong> a resource available again after the process has finished using it.
context2: Around 1943 the USA began to use the technology on a large scale to <strong>make</strong> rugged radios for use in World War II. After the war, in 1948, the USA released the invention for commercial use. Printed circuits did not <strong>become</strong> commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army.