Memory Card: What’s the difference between ROM and RAM?

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Memory, in this article, I don’t mean the human memory. It’s the memory card, a hardware which is used in computers, servers and other devices. As technology developed, now there are many types of memory card. The main types are ROM and RAM.

What are they?

Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing software that is rarely changed during the life of the system, sometimes known as firmware. Software applications for programmable devices can be distributed as plug-in cartridges containing read-only memory.

ROM also includes:

  • PROM – Programmable Read Only Memory
  • EPROM – Erasable Programmable Read Only Memory
  • EEPROM – Electrically Erasable Programmable Read Only Memory


Random-access memory (RAM) is the most common type of memory used for a Rapid-Access Memory which is a form of computer data storage that stores data and machine code currently being used.

A Random-Access Memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory. In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.

RAM also includes:

  • SRAM – Static RAM (including Cache L1, Cache L2 and Cache L3)
  • DRAM – Dynamic RAM

DRAM is the most popular memory card, that is used in many devices in the market.

Here shares an image of DRAM packages, types & uses.


We now know the concept of ROM and RAM, but what are their differences?

  1. Both ROM and RAM are a kind of storage technology, but the two principles are different. RAM is random storage, power loss will not save data, and ROM can save original data in case of power failure. ROM is the meaning of Read Only Memory, which means that this memory can only be read and cannot be written. RAM is an abbreviation for Random Access Memory. RAM can be read and written randomly.
  2. In the computer, everyone knows that there is memory and hard disk. In fact, memory is a kind of RAM technology, and ROM is similar to hard disk technology. Both are memory, but the speed of RAM is much higher than the speed of ROM.
  3. In the mobile phone, RAM refers to the mobile phone memory, which belongs to the internal memory of the mobile phone. It belongs to the random storage and is faster than the ROM. It plays an important role in the performance of the mobile phone. In addition, after the power is turned off, the data is cleared. For example, the mobile phone runs facebook and other Software, after restarting the phone, the software is not logged in.
  4. ROM is an external storage. For example, we can often buy an SD card into the mobile phone, which is the mobile phone ROM. The mobile phone ROM is the memory card we usually say, and it can also be simply understood as a mobile phone hard disk. It is used to store mobile phone system files, pictures, movies, etc., and will not lose data with power loss. The larger the ROM, the more data is stored.

Do you know the differences now? If you have different idea, leave your comment.


Learn More:

HPE Persistent Memory/NVDIMMs for HPE ProLiant Servers


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