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What is Computer Memory?

Computers. What are they, exactly? Big hunks of plastics and precious metals? Yes. But what sets them apart from all the other hunks of plastic and metal around your house is their ability to recall and process data.

Memory is one of the key components of modern computing. Without computer memory, our devices would have little use to us, making life look far different than it does today.

But computer memory units are more than what stores a thousand pictures of your cat sleeping. Memory is also what lets your device perform routine functions like going online or creating a document.

What are the types of computer memory?

Primary and secondary computer memory are the two categories all other types of memory in a computer fall within. They perform very different functions and support the device in unique ways. Let’s use an analogy to help understand the difference.

Think of computer memory as a row of cubbies in a preschool. When the kids arrive, they load up their cubbies with their jackets, backpacks and snacks—whatever they will need to use while they’re at school. When school is over, they (should) clear out their cubbies and take everything home, leaving their cubbies empty once again. This is how primary storage works. The information should be kept only as long as needed and released when the device is no longer in use.

Conversely, at the start of every year, the teacher labels each cubby with the name of a student. This is the secondary computer memory. These labels remain on the cubbies for the entire year or until the teacher decides to manually make a change. Just like how data on secondary memory remains until the user specifically decides to do away with or change the information.

This is an admittedly simple explanation of primary and secondary memory, but you get the idea. Now we can take a deeper dive into each type of memory in a computer.

Primary computer memory

This type of memory in a computer is located close to the CPU on the device’s motherboard. Due to the proximity, primary data can be quickly read by the CPU. Data is saved to the primary memory for immediate use, typically during a single session.

Primary computer memory is divided into two main types: RAM and ROM.

#1. Random Access Memory

Most people know RAM as the type of computer memory that has the strongest impact on a computer’s operating speed. RAM, which stands for Random Access Memory, is extremely fast. And the more RAM you have, the faster your machine will be.

RAM is volatile data, meaning all information stored in RAM is erased as soon as the machine loses power. Overall, this type of memory has a high cost-per-gigabyte. But it’s usually worth using if speed of recall is a concern.

There are two types of RAM computer memory:

  • DRAM: This type of RAM is called Dynamic RAM and is the most common type of RAM used in computers. DRAM is the slower of the two types of ROM. And it’s usually cheaper!
  • SRAM: This type of RAM is called static RAM. As previously mentioned, SRAM is two to three times faster than DRAM and is usually bulkier and more expensive, as well.

#2. Read-Only Memory

ROM is the other type of primary computer memory and stands for Read-Only Memory. As the name implies, this type of primary memory can only read, not write, data. ROM is a very fast form of non-volatile memory, so information stored in ROM remains even after power is lost.

ROM begins working as soon as the computer’s turned on. The drive usually has a “bootstrap code” stored in secondary memory that instructs the computer on how to engage the operating system. ROM also inputs parts of the operating system into primary memory for startup.

There are several types of ROM used to carry out these functions:

  • PROM: Programmable Read-Only Memory is a little bit different from regular ROM because ROM comes programmed. PROM comes empty and is programmed later with a PROM programmer or burner.
  • EPROM: Erasable Programmable Read-Only Memory is a form of ROM that can be programmed, erased, then programmed again. But to erase an EPROM, you must remove the device from the computer and shine ultraviolet light onto the disk before reprogramming.
  • EEPROM: Electrically Erasable Programmable Read-Only Memory is similar to EPROM. This form of ROM is far more difficult to write and is usually considered read-only—though not strictly. Writing to EEPROM is a slow process and is only rarely done to update program code.

These important forms of primary computer memory are what make your device function. They contain everything you need to compute but only while you’re computing. The moment your machine is turned off, the primary memory is erased and reset, because the information is simply no longer needed. Information stored on the secondary computer memory, however, is a much different story.

Secondary computer memory

Secondary computer memory is where you save things you want to keep. Data like documents, those photos of your sleeping cat, and videos.

Almost everything about secondary computer memory is different from primary, and the contrast begins with the location. Unlike primary memory that is stored on the motherboard, secondary memory resides on a separate storage device connected to the computer system directly or through a network.

Secondary memory is much more affordable than primary. But you get what you pay for, because the read and write speeds are much slower. In the case of secondary computer memory, slow doesn’t always mean bad. What’s considered slow by computing standards is often only fractions of a second to you.

There are many types of secondary computer memory. You’re probably using a combination of these options for backup or simply as overflow. Here’s a breakdown of what’s available:

  • Hard Disk Drives (HDDs): HDDs were once the most popular form of computer storage but have become antiquated with the rise of solid state hard drives.
  • Solid State Drives (SSDs): SSDs are the most common form of secondary storage today. These drives use flash technology to quickly and efficiently store data.
  • Flash Drives: Flash is the technology used in standard issue USB (or thumb) drives to sophisticated SSDs. This type of storage is perfect when you want optimal portability. And unlike HDDs, since flash drives don’t have moving parts, you don’t need to worry about physical damage during transport. 
  • Optical (CD or DVD) Drives: CD or DVD drives were once a very popular form of portable data storage. But today most everyone uses cloud-based storage solutions and smaller, less fragile forms of mobile data storage.

Every computer has primary and secondary memory, but the configuration depends on you and your goals. No matter how your storage is configured, be aware of the risks of data loss.

If your computer or drive has failed, and you’re struggling to access your data, contact DriveSavers today for professional data recovery.

Mike Cobb, Director of Engineering and CISO
As Director of Engineering, Mike Cobb manages the day-to-day operations of the Engineering Department, including the physical and logical recoveries of rotational media, SSDs, smart devices and flash media. He also oversees the R&D efforts for past, present, and future storage technologies. Mike encourages growth and ensures that each of the departments and their engineers continues to gain knowledge in their field. Each DriveSavers engineer has been trained to ensure the successful and complete recovery of data is their top priority.

As Chief Information Security Officer (CISO), Mike oversees cybersecurity at DriveSavers, including maintaining and updating security certifications such as SOC 2 Type II compliance, coordinating company security policy, and employee cybersecurity education.

Mike joined DriveSavers in 1994 and has a B.S. degree in Computer Science from the University of California, Riverside.

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