ROM (Read-Only Memory)

Read-only memory, sometimes known as ROM, is a kind of permanent, non-volatile computer storage that is typically only readable and not writeable. The software that enables a computer to boot up or restart every time it is switched on is stored in read-only memory (ROM). Large input/output (I/O) operations are also carried out by ROM, which also safeguards software instructions. Data cannot be erased from a ROM chip after it has been written there.

The start-up firmware is included in a tiny piece of ROM found in almost all computers. The basic input/output system (BIOS) is the name given to this boot firmware. This software comprises of code that directs the computer's boot-up procedures, including launching hardware diagnostics or installing the operating system (OS) in random access memory (RAM). Consequently, firmware upgrades are often performed via ROM.

ROM is also used in video game consoles, though, so several games may run on a single device. Moreover, optical storage, such as various compact disc (CD) types including CD-ROM and CD-RW, uses ROM. Calculators and other peripherals like, whose typefaces are often stored in ROM, also routinely utilise ROM.

ROM types

MaskROM (MROM) is another name for ROM. MROM is a type of static read-only memory that is pre-programmed by the manufacturer onto a circuit that is provided. One sort of maskROM is solid-state ROM, which is the earliest kind of ROM. Since the original ROM was completely read-only, any changes to its contents required physically removing and replacing it.

But other forms of ROM have also surfaced that fall under the category of programmable read-only memory (PROM); these are still non-volatile but have the ability to be reprogrammed. By using installation software, PROM may be utilised to upgrade firmware, including BIOS.

PROM types include:

• UV-ROM, or ultraviolet-erasable ROM, is a kind of ROM that can have its contents removed and reprogrammed using ultraviolet radiation.

• Erasable programmable ROM (EPROM): This kind of ROM is programmed by applying high voltages and spending around 20 minutes in the sun.

• Electrically-erasable programmable ROM (EEPROM): EEPROM is frequently found in older computer chips and is used to operate the BIOS. It allows the writing and erasing of just one area at a time and may be repeatedly erased and reprogrammed. An improved form of EEPROM that enables simultaneous changes to several memory areas is called flash memory.

How does ROM operate?

A tiny, long-lasting battery within the computer powers the ROM. The decoder and the OR logic gates are its two main parts. The decoder in ROM processes binary input and outputs its decimal representation. The decimal output of the decoder is the input for the OR gates in ROM.

Similar to a disc array, ROM operates. To switch the system on and off, a grid of rows and columns is included. Each entry in the array corresponds to a particular ROM chip memory element. The matching components are connected via a diode.

The address input is used to determine the precise memory location upon receipt of a request. The selected array element's contents should match the value that is read from the ROM chip.

RAM vs. ROM

The data stored in ROM is not erased when the computer's power is switched off, in contrast to RAM. Although the RAM chip is frequently utilised for the computer's ongoing duties once the operating system has been configured, the ROM chip is typically employed for the computer's starting processes.

The quantity of space that separates RAM and ROM is another distinction. The maximum amount of data that ROM chips can hold is a few megabytes (MB), often between 4 and 8 MB per ROM chip. multiple gigabytes (GB) of storage may be stored on RAM chips; typically, a RAM chip can contain between 1 and 265 GB of data. One gigabyte is said to be equal to 1000 millibytes. RAM has more broad memory capacity as a result.

Using ROM alone to run a computer is nearly difficult. RAM is required to execute programmes that are flexible and helpful. Computers must thus support both types of memory.

Benefits of ROM

The instructions required for various hardware components to communicate with one another are provided via ROM. It can be used for basic data management, to store software for basic utility activities, to read and write to peripheral devices, and, as previously indicated, is necessary for the storage and functioning of the BIOS.

Additional benefits of ROM include:

• Because of its static nature, it doesn't need to be refreshed.

• Testing it is simple.

• Because ROM is non-volatile and cannot be mistakenly modified, it is more dependable than RAM.

• There is always a means to know and confirm the contents of the ROM.

• cheaper than RAM.