ROM

acronym for read only memory. there are two basic types of ROM. ROM manufactured and sold with bit patterns already burned in and PROM. PROMs can be programed by the user only once.

there is a third type called EAROM for electrically alterable ROM. these roms can be programmed on the fly over and over.

ROMs are used for memory that never changes. BASICs interpreter is in ROM. the jump addresses for interupts are in ROM. the start address for the CPU is in ROM.