A programmable read-only memory (PROM) is a form of digital memory the place the contents will be modified as soon as after manufacture of the device. The information is then permanent. It is one type of learn-solely Memory Wave clarity support (ROM). PROMs are normally utilized in digital electronic gadgets to store low stage applications comparable to firmware or microcode. PROMs may be used throughout development of a system that may finally be transformed to ROMs in a mass produced model. These kind of reminiscences are utilized in microcontrollers, video sport consoles, cellphones, radio-frequency identification (RFID) tags, implantable medical gadgets, excessive-definition multimedia interfaces (HDMI), Memory Wave and in lots of other client and automotive merchandise. PROMs are manufactured clean and, relying on the technology, may be programmed at the wafer, ultimate test, or system stage. Clean PROM chips are programmed by plugging them right into a system known as a PROM programmer. A typical PROM gadget has an array of memory cells.

The bipolar transistors in the cells have an emitter that is related to a fuse known as a polyfuse. To program a PROM is to strategically blow the polyfuses. The PROM was invented in 1956 by Wen Tsing Chow, working for the Arma Division of the American Bosch Arma Company in Backyard Metropolis, New York. The invention was conceived at the request of the United States Air Pressure to provide you with a extra versatile and secure way of storing the targeting constants within the Atlas E/F ICBM's airborne digital laptop. The patent and related know-how were held under secrecy order for several years whereas the Atlas E/F was the principle operational missile of the United States ICBM force. The term burn, referring to the strategy of programming a PROM, is also in the original patent, as one in all the unique implementations was to literally burn the inner whiskers of diodes with a present overload to produce a circuit discontinuity. The first PROM programming machines were also developed by Arma engineers under Chow's route and had been positioned in Arma's Garden Metropolis lab and Air Force Strategic Air Command (SAC) headquarters.

OTP (one time programmable) memory is a particular kind of non-risky memory (NVM) that permits information to be written to memory only once. Once the memory has been programmed, it retains its worth upon lack of energy (i.e., is non-volatile). OTP memory is used in applications where dependable and repeatable reading of data is required. Examples embody boot code, encryption keys and configuration parameters for analog, sensor or display circuitry. OTP NVM is characterized, over other forms of NVM like eFuse or EEPROM, by offering a low power, small space footprint Memory Wave construction. As such, OTP memory finds application in products from microprocessors & display drivers to power administration ICs (PMICs). Commercially available semiconductor antifuse-based mostly OTP memory arrays have been round not less than since 1969, with preliminary antifuse bit cells dependent on blowing a capacitor between crossing conductive lines. Early oxide breakdown technologies exhibited a variety of scaling, programming, size and manufacturing issues that prevented volume manufacturing of memory gadgets primarily based on these applied sciences.

Another type of one-time programmable memory system uses the same semiconductor chip as an ultraviolet-erasable programmable read-solely memory (UV-EPROM), however the completed gadget is put into an opaque bundle, as an alternative of the expensive ceramic bundle with clear quartz window required for erasing. These devices are programmed with the same strategies because the UV EPROM components however are less expensive. Embedded controllers may be obtainable in each subject-erasable and one-time kinds, permitting a cost saving in volume manufacturing with out the expense and lead time of manufacturing facility-programmed mask ROM chips. Although antifuse-primarily based PROM has been obtainable for many years, it wasn’t out there in customary CMOS until 2001 when Kilopass Expertise Inc. patented 1T, 2T, and 3.5T antifuse bit cell technologies using a normal CMOS course of, enabling integration of PROM into logic CMOS chips. The first process node antifuse will be carried out in customary CMOS is 0.18 um. Because the gate oxide breakdown is less than the junction breakdown, particular diffusion steps weren't required to create the antifuse programming component.