Programmable read only memories, commonly known as PROMs, refer to electronic chips used to store permanent data. The spelling of "programmable read only memories" can be explained using the International Phonetic Alphabet (IPA), where "proh-gram-uh-buhl reed ohn-lee mem-uh-reez" can be transcribed as /ˈprəʊ.ɡræ.mə.bəl ˈri.dəʊ ˈəʊn.li ˈmeməriz/. Each syllable is pronounced with stress on the second or third syllable, and the "oh" sound is used for the "o" in "programmable" and "read." The "a" in "memories" is pronounced as the "uh" sound.
Programmable Read Only Memories (PROMs) are integrated circuits that store digital information and can be programmed by the user, making them a type of non-volatile memory. PROMs are designed for permanent storage of data and instructions that remain unchanged even when the power supply is removed.
These memories consist of an array of memory cells, typically made of transistors, arranged in rows and columns. Each memory cell can store a single bit of data, either a 0 or a 1. The cells are initially in a blank state, where the stored information is erased.
To program a PROM, a device called a PROM programmer is used. This programmer applies a high voltage to selected memory cells, which causes them to permanently store a desired binary value. Once programmed, the information remains fixed and cannot be modified or erased. This characteristic makes PROMs different from other types of programmable memories, such as EPROMs (Erasable Programmable Read Only Memories) or EEPROMs (Electrically Erasable Programmable Read Only Memories), which allow for reprogramming or erasing of data.
PROMs are commonly used in various electronic systems, such as in microcontrollers, calculators, and industrial control devices. They offer a cost-effective solution for storing small amounts of fixed data that do not require frequent updates. Additionally, PROMs provide a reliable and secure way of storing information, ensuring its integrity in critical applications or systems.