We explain what ROM memory is and what this type of storage is for. Also, the types of ROM and what RAM is.
What is ROM memory?
In computing, when we talk about ROM memory (acronym for Read–Only Memorythat is, Read Only Memory), we refer to a type of storage used in computers and other electronic devices which is characterized by being accessible only for reading and never for writing, that is, it can be recovered but not modified or intervened.
The ROM memory is sequentially accessed and its presence is independent of the presence of a power source. As has been said, its content cannot be modified or at least not in a simple and everyday way, and usually contains information introduced into the system by the manufacturer, of a basic, operational or primary type.
This type of memory also operates in a way much slower than its counterpart, RAM (acronym of Random Access Memorythat is, Random Access Memory), so its contents are usually dumped into the latter to execute faster.
There are, however, versions of ROM memory (known as EPROM and Flash EEPROM) that can be programmed and reprogrammed several times despite the fact that its operation is governed by the same rules as traditional ones. However, since their reprogramming process is infrequent and relatively slow, they continue to be called the same way.
See also: Cache memory
What is ROM memory used for?
ROM memory has two main uses, which are:
- Software storage Commonly, computers in the 1980s came with their entire operating system stored in ROM, so that users could not alter it by mistake and interrupt the operation of the machine. Even today it is used to install the most basic boot or operating software (BIOS, SETUP and POST, for example).
- Data storage. Since users do not usually have access to a system's ROM, it is used to store data that will not require any modification during the life of the product, such as lookup tables, mathematical or logical operators, and other technical information.
Types of ROM memory
Let's consider three different types of ROM memory:
- AVG Acronym of Programmable Read–Only Memory (Programmable Read Only Memory), is digital and can be programmed only once, since each memory unit depends on a fuse that burns when doing so.
- EPROM Acronym of Erasable Programmable Read–Only Memory (Erasable and Programmable Read Only Memory) is a form of PROM memory that can be erased by exposure to ultraviolet light or high levels of voltage, erasing the information contained and allowing it to be replaced.
- EEPROM Acronym of Electrically Erasable Programmable Read-Only Memory (Electrically Erasable and Programmable Read Only Memory) is a variant of EPROM that does not require ultraviolet rays and can be reprogrammed in the circuit itself, being able to access the bits of information individually and not together.
RAM memory
Unlike ROM, RAM memory is much faster and freely writable. This means that all running programs go to this memory bank but in a strictly temporary manner: when you turn off or restart the system, the entire RAM memory is cleaned. This does not mean, of course, that the information saved on disk is lost, but only that which is running.
RAM memory It is today extremely efficient, fast and economical so many system engineers prefer to use it instead of ROM.
