ABSTRACT
Programmable memories operate more like read-only memories in that they can be programmed at least once, and some can be reprogrammed a million times or more. Flash Electrically erasable programmable read-only memory (EEPROMs) describe a family of single-transistor cell EEPROMs. Cell sizes are about half that of two-transistor EEPROMs, an important economic consideration. ROM is the only form of semiconductor storage that is permanently nonvolatile. Information is retained without applied power, and there is no information loss as in EEPROMs. Read-only memory applications include look-up tables, machine-level instruction code for computers and small arrays to perform logic. Information is stored on magnetic tape in the form of a coherent sequence of rows forming a block. This usually corresponds to a page of computer memory and is the minimum amount of data written to or read from magnetic tape with each program statement. A disk, whether magnetic or optical, consists of a number of tracks along which the information is recorded.
