What is ROM memory?

While not usually given as much attention as with RAM and processor, ROM is also one of the most important components of a computer, because it is a link more than fundamental in the chain of starting of a PC. Your mission is store all the necessary parameters so that every time we turn on the PC, remember how and in what order you should do it, among other tasks.

This electronic component has been present in motherboards since the very beginning of the computer, but it can also be found in cell phones, tablets and many other devices that require a boot routine. If you want to know everything about this electronic component of computers and phones, please read on this article on ROMs, where you will find clear and concise information on its operation, the different types of ROM that exist and many other very interesting information on the subject.

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What is ROM memory?

ROM memory is an electronic component that can be found in computers and portable devices such as cellphones, cellphones and tablets, but we can also find it in smart TVs, audio players and many other types of devices conforming to the function of storing the data and instructions required to start the device, that is to say to start, normally.

Notably ROMs can be written, but by special procedures like the ones we use When we update the BIOS of the computer to improve its functions, a task that can be easily accomplished these days, and is even encouraged by most motherboard manufacturers.

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What does ROM mean?

The term ROM is the abbreviation of “Read-only memory” what in our language means “Read-only memory”, and that as the name suggests, it stores information and instructions that can only be read, In other words, new data cannot be written to this type of memory, unlike RAMs, as we can see later in this post.

As we mentioned, ROM memory is a chip or integrated circuit capable of storing information inside, which cannot be changed, at least accidentally. Besides The ROM memory can retain the data recorded in its circuits even when it is not powered on, that is to say when there is no power supply to keep them there, unlike RAM memories which, in the absence of power supply to supply them, immediately lose the contents of their cells.

This makes ROM extremely efficient in being able to boot an electronic device such as a computer, a smartphone or any other device that needs to always start in the same way, since the data and startup routines it stores inside will always be stored there, and in the same condition in which they were stored.

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ROM function

Essentially the role played by ROM memories within devices, Specifically in the case of computers, it’s about keeping all the necessary boot codes and instructions stored and unchanged so that the PC can boot every day and every time we turn it on the same way.

Among the many PC startup process management tasks which runs the ROM, One of them is extremely important: to start the operating system of the PC, without which, as we know, a computer nowadays would be of very little use. But in addition, the ROM memory is responsible for performing all the initial analysis and checks of the system, as well as the multiple routines for checking all the input and output devices.

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Types of ROM

Basically, the memories used to store a device’s boot routines are divided into two types: those that are programmable and those that are not. The second type, composed of ROM memories and PROM memories, They are no longer used in the field of computing, since they have been replaced by overwritten memories, that is to say memories of the first type, among which are EPROM and EEPROM memory.

Below these lines we will know the fundamental differences between ROM, PROM, EPROM and EEPROM.

ROM (read-only memory)

ROM (Read Only Memory) or Read Only Memory This was the first type of ROM that was manufactured, and in order to store information in it, a procedure was used which involved the use of a silicone plate and a mask, so any possibility of being able to to do it manually was impossible. . ROM type memories have been replaced by EPROM and EEPROM type memories, that could be overwritten.

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PROM (programmable read only memory)

PROM (Programmable Read-Only Memory) or Programmable Only Memory Reading, This is a military development from the mid-1950s. The most striking thing about this type of memory is that the data logging procedure on the chip was carried out by applying a voltage overload, between 12 and 20 volts, to the diodes in the integrated circuit, through a device called “ROM Programmer”.

The chips came out of the factory with all diodes intact, all corresponding to the value “1” – When overloaded, they had a value of “0”. As can be seen, it was also not possible to do this manually. This type of PROM has been used in Sinclair ZX Spectrum computers, among others.

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It should be noted that the term “burn down”, used for this type of activity, it comes from the burning under voltage of the diodes of these memories.

EPROM (erasable programmable read only memory)

EPROM type memories (Erasable Programmable Read Only Memory) or Programmable and Erasable Read Only Memory, they are essentially PROM type memories but unlike these, they offer the possibility of being able to erase the content stored therein.

EPROMs are programmed by emitting rays of ultraviolet light, which enter the circuit through a window in the integrated circuit housing.

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EEPROM (Electrically Erasable Programmable Read Only Memory)

EEPROM memories (Electrically Erasable Programmable Read Only Memory), or electrically erasable programmable read only memories, they are erasable, like EPROM memories, except that in this case the procedure of erasing and rewriting the memory is much simpler, since an electric current is used.

EEPROM memories offer a variant called Flash EEPROM, which uses fewer components, and is able to read the registers it contains one by one, which affects the performance of the chip.

Differences between ROM, EPROM and Flash EEPROM

Although the term ROM is still used today, the truth is that things have changed a bit, since the “Only Read” contained in the acronym is no longer true, because memories like this today can be written many times and quite simply. An example of this is when update BIOS.

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remember that The term ROM comes from a time when ROMs left the factory already saved with data and instructions. that they had to have depending on the device in which they were going to be installed, and there was no possibility of being able to modify their content.

Currently, the term ROM is still used by simple convention, since new memories of this type, which have replaced the old ROMs in recent years, and thanks to which practically We cannot find a device on the market that still has one of the old ROMs installed, yes, they can be written.

This type of ROM memory is called EPROM and Flash EEPROM, And while we must have some specialized knowledge, experience, and software tools to modify its contents, the truth is that the routine of modifying the contents of a modern ROM is pretty straightforward.

But the most important thing to remember is that Unlike ROM memories, EPROM and Flash EEPROM memories can be written, that is, record new data, several times. This fact allows, for example, to update the BIOS and to take advantage of the new characteristics of this one and by our own means and without presenting significant problems in the procedure.

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Difference between RAM and ROM

In a computer, there are two types of memory, RAM memory and ROM memory, each fulfilling a specific objective. RAM, or random access memory, fulfills the function of storing the data most used by the operating system and user applications, a much faster method than having to search for them directly on the hard drive.

In addition, the RAM memory can be overwritten several times, but its content, i.e. the data stored in it, is temporary, which means that in the event of a power failure, they will be lost.

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On the contrary, the content stored in the ROM memory is not deleted in the event of a power failure, which, as we have mentioned, makes it the ideal substrate for the boot functions of a computer, and since it cannot be written, at least by simple means and by hand of any user, ensures that the device will always start in the same way.