Computer - Read Only Memory

Computer - Read Only Memory

ROM stands for Read Only Memory. The reminiscence from which we are able to most effective study however cannot write on it. This form of memory is non-risky. The information is stored completely in such memories during manufacture. A ROM shops such instructions which might be required to start a pc. This operation is known as bootstrap. ROM chips are not handiest used in the pc however additionally in other electronic gadgets like washing system and microwave oven.

Let us now discuss the numerous styles of ROMs and their characteristics.

MROM (Masked ROM)

The first actual ROMs have been tough-wired gadgets that contained a pre-programmed set of statistics or commands. These sort of ROMs are known as masked ROMs, that are less expensive.

PROM (Programmable Read Only Memory)

PROM is study-only memory that may be changed most effective as soon as by a consumer. The person buys a clean PROM and enters the favored contents using a PROM software. Inside the PROM chip, there are small fuses that are burnt open at some point of programming. It may be programmed handiest once and isn't always erasable.

EPROM (Erasable and Programmable Read Only Memory)

EPROM may be erased by way of exposing it to extremely-violet mild for a period of up to 40 minutes. Usually, an EPROM eraser achieves this function. During programming, an electrical price is trapped in an insulated gate vicinity. The rate is retained for extra than 10 years because the fee has no leakage direction. For erasing this fee, ultra-violet mild is passed through a quartz crystal window (lid). This publicity to ultra-violet light dissipates the fee. During ordinary use, the quartz lid is sealed with a sticker.

EEPROM (Electrically Erasable and Programmable Read Only Memory)

EEPROM is programmed and erased electrically. It may be erased and reprogrammed approximately ten thousand instances. Both erasing and programming take about four to 10 ms (millisecond). In EEPROM, any location can be selectively erased and programmed. EEPROMs can be erased one byte at a time, in preference to erasing the whole chip. Hence, the process of reprogramming is flexible but gradual.

Advantages of ROM

The advantages of ROM are as follows −

Non-risky in nature

Cannot be accidentally modified

Cheaper than RAMs

Easy to check

More reliable than RAMs

Static and do no longer require clean

Contents are usually recognised and may be validated