Programmable read-only memory
Programmable Read Only Memory (PROM) is a read-only memory that can be programmed directly by the user using a special PROM programmer. It is also sometimes called a fusible-link PROM. It is a control memory in which stored information can be altered, but not as easily as in ordinary memory. In some PROM'S the contents may be erased by ultraviolet rays/light and then rewritten. Once written into PROM chip they are made permanent and cannot be deleted.