What Are the Differences Between RAM and ROM Memory?

RAM vs ROM. What Are the Differences Between RAM and ROM Memory
What Are the Differences Between RAM and ROM Memory?

All PCs need several types of memory to work together. There is RAM, but also RAM and ROM, two types of memory that are sometimes confused. For this reason, today we’ll explain what the differences are, what types there are, and what each of them is used for.


RAM memory is probably one of the components we usually talk about when it comes to PC hardware, and you can buy it at any computer store. Although you may not know it, computers also have ROM memory, which is essential for their operation. Let’s take a look at what each of these types of memory is and what they are used for, to understand their differences.

RAM Memory

RAM memory
RAM memory

The name RAM stands for Random Access Memory. It is so-called because its contents are constantly changing, depending on what the PC needs at the moment – and it is managed by the processor. It is used to store the programs and data that are being used at a particular time so that the processor can access them immediately and in real time.

A head-to-head comparison between RAM and ROM shows that RAM is several hundred times faster.

This type of memory is volatile, i.e. all the information stored in it disappears when the PC is switched off. Therefore, secondary memory is necessary to store the programs that are to be executed on the PC. This secondary memory, unlike RAM, is not used to run programs because it is not fast enough.

Types of RAM

RAM Variable Speed
RAM Variable Speed

Among the existing RAM memories, there are currently two types:

  • DRAM: stands for Dynamic RAM and is most commonly used in PCs and actually in almost all devices, including smartphones. This type of memory consists of capacitors that require the controller to save the data stored in it several times per second so that it is not lost. It is used for conventional RAM and, unlike SRAM, it must be refreshed every few seconds to preserve the data.
  • SRAM: stands for Static RAM, and as the name suggests, it is static. In this case, the data is stored until the power supply is interrupted, without the controller having to constantly update the data; it is faster and consumes less power than DRAM. But it is less used because it is more expensive to manufacture and allows much lower densities (capacities). SRAM is used in both CPUs and GPUs for caches and registers.

On the other hand, it should be clarified that NVRAM, Non Volatile RAM, refers to NAND flash memory, especially DIMM memory modules that contain NAND flash memory chips instead of conventional RAM. Regardless of the type of flash memory, it is not used as RAM. Except in components that operate at very low clock rates.

ROM Memory

ROM memory chips
ROM memory chips

Data in ROM can not be modified. ROM memory is named after Read Only Memory or read only memory. The main difference between RAM and ROM is that ROM is non-volatile, meaning that the stored information is retained even if the PC is turned off. This type of memory has a much smaller capacity than RAM and is also much slower.

In the first computers, due to the fact that the memory used was very slow, since magnetic disks or tapes were usually used, usually included a ROM in which the operating system and its BIOS were loaded.

ROM memory is no longer used as soon as speed prevails and latency becomes too high. When this phenomenon occurred, hard disks in PCs began to be standardized.

Types of Fixed Storage

ROM memory
ROM memory

Originally, ROM memory was read-only memory, but for some time now it has simply been non-volatile memory that can also be written… in some special ways. For example, ROM memory stores BIOS (which we know can be updated) and device firmware. These are the main types of ROM memory used today:

  • Mask ROM: This type of memory is used during the manufacturing process of the device, and once the data is written, it cannot be changed.
  • PROM: stands for “Programmable ROM”, and as the name suggests, the data stored in it can be programmed (unlike mask ROM, after the manufacturing process). The peculiarity is that once written, this data can never be changed.
  • EPROM: stands for Electrically Programmable ROM and is similar to PROM but allows data to be erased under certain conditions (essentially by irradiation with intense ultraviolet light).
  • EEPROM: stands for Electrically Erasable Programmable ROM and is the most commonly used type of ROM because it allows data to be erased and rewritten an unlimited number of times.

A curiosity is that many of the fixed-function chips used in old hardware were built with ROM memory. These chips, starting from certain input data, always end up executing the same “program” encoded in ROM. However, this encoding is not binary as in a conventional RAM or ROM. The bits that pass through the various transistors of the ROM are intended to be manipulated in a particular way to produce a particular result.

In Short, What Are the Differences?

RAM assembly
RAM assembly

The main differences between RAM and ROM are the following: Essentially, RAM is a type of temporary memory. Ram stores data that the processor needs to access immediately so it doesn’t have to search for it in system memory, or calculations that the processor has performed and needs to use later so it doesn’t have to recalculate them.

The difference between RAM and ROM is not only that it is a read-only memory (i.e. it is not volatile, but the data is retained even without power), but also that it is read-only and cannot be written back. This type of memory stores things like BIOS or device firmware.

We describe in detail the difference between RAM (Random Access Memory) and ROM (Read Only Memory) on this page. RAM is a type of memory used to store working data and machine code. Ram can be read and changed in any order.

The name ROM stands for non-volatile memory in computers. Meaning that the data is permanently stored on the chip.

Video Guide: RAM Vs. ROM. Video Made By: EarthPen

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