Information and Communication Technology

2.1.14 Read Only Memory (ROM)

ROM is a type of memory that can be read from but cannot be written to. ROM is non-volatile, meaning that it retains its content seven when the power is shut off. ROM is used as a part of the main memory to store programs that perform some special tasks. These programs are written permanently into the memory during manufacture. Such programs are called the firmware. Firmware technology has led to the development of several types of ROM. They include:

• Programmable ROM (PROM )
• Erasable PROM (EPROM)
• Electrically alterable ROM (EAROM)

PROM This is a type of ROM that may be customised to the needs of the users. That is, data and programs can be written in it after manufacture but once written, it becomes permanently fixed.

EPROM This is a type of ROM that may be reused. That is, the contents of EPROMs may be erased by a special process and then reprogrammed/rewritten again by the user.

EAROM This state-of-the-art ROM chips that may be erased and reprogrammed using an el ectrical signal to change the bit pattern of the program.