A programmable read-solely memory (PROM) is a type of digital memory where the contents will be modified as soon as after manufacture of the device. The information is then permanent. It's one sort of learn-only memory (ROM). PROMs are often utilized in digital electronic gadgets to retailer low stage applications such as firmware or microcode. PROMs may be used throughout improvement of a system that may finally be converted to ROMs in a mass produced model. These types of recollections are used in microcontrollers, video sport consoles, cellphones, radio-frequency identification (RFID) tags, implantable medical gadgets, high-definition multimedia interfaces (HDMI), and in many different shopper and automotive products. PROMs are manufactured blank and, relying on the know-how, can be programmed at the wafer, remaining check, or system stage. Blank PROM chips are programmed by plugging them right into a device called a PROM programmer. A typical PROM device has an array of memory cells.

The bipolar transistors in the cells have an emitter that is linked 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 Corporation in Backyard City, New York. The invention was conceived at the request of the United States Air Force to give you a more flexible and safe manner of storing the targeting constants in the Atlas E/F ICBM's airborne digital laptop. The patent and related technology had been held under secrecy order for several years whereas the Atlas E/F was the principle operational missile of the United States ICBM drive. The time period burn, referring to the technique of programming a PROM, can also be in the original patent, Memory Wave as one in all the unique implementations was to literally burn the inner whiskers of diodes with a current overload to provide a circuit discontinuity. The first PROM programming machines have been additionally developed by Arma engineers under Chow's direction and were positioned in Arma's Backyard Metropolis lab and Air Force Strategic Air Command (SAC) headquarters.

OTP (one time programmable) memory is a particular type of non-volatile Memory Wave focus enhancer (NVM) that permits information to be written to memory solely once. As soon as the memory has been programmed, it retains its value upon loss of power (i.e., is non-volatile). OTP memory is used in applications where reliable and repeatable studying of knowledge is required. Examples include boot code, encryption keys and configuration parameters for analog, sensor or display circuitry. OTP NVM is characterized, over different forms of NVM like eFuse or EEPROM, Memory Wave by offering a low power, small space footprint memory construction. As such, OTP memory finds application in merchandise from microprocessors & show drivers to power management ICs (PMICs). Commercially available semiconductor antifuse-primarily based OTP memory arrays have been round a minimum of since 1969, with preliminary antifuse bit cells dependent on blowing a capacitor between crossing conductive lines. Early oxide breakdown applied sciences exhibited a variety of scaling, programming, measurement and Memory Wave focus enhancer manufacturing issues that prevented volume manufacturing of memory gadgets based on these applied sciences.

Another form of 1-time programmable memory system makes use of the identical semiconductor chip as an ultraviolet-erasable programmable read-solely memory (UV-EPROM), but the completed gadget is put into an opaque bundle, instead of the expensive ceramic bundle with transparent quartz window required for erasing. These devices are programmed with the same strategies because the UV EPROM elements however are less expensive. Embedded controllers could also be accessible in each field-erasable and one-time types, permitting a value saving in quantity manufacturing with out the expense and lead time of factory-programmed mask ROM chips. Though antifuse-based mostly PROM has been out there for decades, it wasn’t accessible in normal CMOS till 2001 when Kilopass Technology Inc. patented 1T, 2T, and 3.5T antifuse bit cell technologies using a standard CMOS process, enabling integration of PROM into logic CMOS chips. The primary course of node antifuse might be applied in customary CMOS is 0.18 um. For the reason that gate oxide breakdown is less than the junction breakdown, special diffusion steps weren't required to create the antifuse programming factor.