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Principles of Robotics & Artificial Intelligence, Second Edition

Computer Memory

by Tyler Biscontini

Fields of Study: Computer engineering; Electronics engineering; Data management

ABSTRACT

Computer memory is the part of the device’s hardware that stores information. There are different types of memory inside a computer, including permanent memory, temporary memory, read-only memory (ROM), random-access memory (RAM), and programmable read-only memory (PROM). Different memory storage devices in a computer are used for different purposes. Fast, temporary memory such as RAM is used to make quick calculations, while ROM and hard disk drives are used for long-term storage. Without memory, computers would not be able to function in any meaningful capacity.

KEY CONCEPTS

caching: the storage of data, such as a previously accessed web page, in order to load it faster upon future access

direct-access storage: a type of data storage in which the data has a dedicated address and location on the storage device, allowing it to be accessed directly rather than sequentially

dynamic random-access memory (DRAM): a form of RAM in which the device’s memory must be refreshed on a regular basis, or else the data it contains will disappear

magnetic storage: a device that stores information by magnetizing certain types of material

main memory: the primary memory system of a computer, often called “random-access memory” (RAM), accessed by the computer’s central processing unit (CPU)

memory dumps: computer memory records from when a particular program crashed, used to pinpoint and address the bug that caused the crash

nonvolatile memory: computer storage that retains its contents after power to the system is cut off, rather than memory that is erased at system shutdown

nonvolatile random-access memory (NVRAM): a form of RAM in which data is retained even when the device loses access to power

shadow RAM: a form of RAM that copies code stored in read-only memory into RAM so that it can be accessed more quickly

solid-state storage: computer memory that stores information in the form of electronic circuits, without the use of disks or other read-write equipment

HISTORY OF THE COMPUTER

In their earliest days, computers were strictly mechanical devices. They used punch cards for memory and output. These machines were developed for utility rather than for the multitude of tasks for which modern computers are designed. They were primarily used for complex calculations.

DDR-SD-RAM, SD-RAM and two older sorts of memory.

PORobot2e_p0116_0001.jpg

Photo by Gyga, via Wikimedia Commons.

Alan Turing, a famous computer scientist, is credited with the idea for the first multipurpose computer. In the 1930s, J. V. Atanasoff created the first computer that contained no gears, cams, belts, or shafts. Atanasoff and his team then designed the first computer with functioning, nonmechanical memory devices. Primitive when compared to today’s devices, Atanasoff’s creation allowed the computer to solve up to twenty-nine equations simultaneously.

The next major leap in computing power came with the use of vacuum tubes. In 1945, professors John Mauchly and J. Presper Eckert completed building the first tube-based electronic calculator, the Electronic Numerical Integrator and Calculator (ENIAC). This is commonly considered the first digital computer. It was a massive machine, taking up the entirety of a large room. They soon began to market this computer to governments and businesses. However, tube computers became obsolete in 1947 with the invention of the transistor, although ENIAC was in continuous operation until 1955 when an electrical surge caused by lightning spelled its doom in the age of transistors.

Ten years after its invention the transistor was used by Robert Noyce and Jack Kilby to create the first computer chip. This spurred the development of the first devices recognizable as modern computers. Computers took another leap forward with the graphical user interface (GUI), which projects options as images on a screen instead of requiring users to learn to code. Computers advanced further with the inventions of random-access memory (RAM) in 1970 and floppy disks in 1971. Floppy disks were a form of quasi-permanent storage used in the early days of computers. They could easily be transferred from one computer to another, making them ideal for transporting information. They were, however, vulnerable to physical damage and being overwritten, and the data they held could be corrupted or even irretrievably eradicated if the disks were near a magnet of any kind. Floppy disks were made obsolete by compact disks read-only memory (CD-ROMs), which are small plastic disks that store large amounts of information that had been laser-etched into a thin aluminum layer within the disk. While CD-ROMs proved many times more robust than floppies, and the data they contained could not be overwritten (until rewritable CDs were invented later), the plastic that they were made from could be easily scratched, making the data beneath the scratch unreadable, and a simple thing such as a fingerprint on the read side of the disk could also interfere with the reading of the data beneath it, requiring careful cleaning.

Solid-state drives are one example of non-volatile memory.

PORobot2e_p0117_0001.jpg

Photo by Intel Free Press, via Wikimedia Commons.

In modern computers, data is store on hard drives, which are essentially like floppy disks, except that the disks within a hard drive are, as the name implies, made of a hard material rather than a flimsy, plastic. Data is inscribed magnetically, just as with floppies, but the mechanical structures that do this, termed read-write heads, are much more finely and precisely manufactured. Furthermore, hard drives are typically housed in a steel box that serves to purposes: it isolates the hard disks from the external world, protecting them from physical harm, and it acts as a Faraday cage, protecting them and their data from electromagnetic interference.

OVERVIEW

Computer memory is measured in binary digits, called bits. One bit is an extremely small amount of information. Eight bits is the equivalent of one byte; 1024 bytes is called a kilobyte (KB); 1024 KB make a megabyte (MB); 1024 MB make a gigabyte (GB); 1024 GB make a petabyte (PB), and 1024 PB make a Terrabyte (TB). Over time, the cost of large amounts of computer storage has drastically fallen. However, the amount of memory required by modern computers has also drastically increased.

Computers contain several types of memory. The most common type is temporary memory, which is designed to hold information for only a short period. Permanent memory is designed to hold memory for a much longer time. Most of a computer’s temporary memory is RAM. RAM is designed to quickly write and erase information. It performs calculations, runs scripts, and enacts most of the computer’s functions. A computer with more RAM can perform more functions at once, making it more powerful.

Permanent storage may refer to several devices. In most cases, information is stored on the computer’s hard disk drive. Most hard disk drives use a spinning disk and an actuator arm. The actuator arm writes to the spinning disk by rearranging electrons in the particles of a magnetically susceptible coating on the disks. In this scenario, the entire inside of the hard disk drive is located inside an airtight seal. These hard drives can be found in many sizes. However, modern hard disk drives are often found in capacities of hundreds of gigabytes to terabytes.

Many high-quality computer manufacturers have begun replacing hard disk drives with solid-state drives (SSDs). SSDs contain no moving parts. In most instances, these drives can read and write data much faster than hard disk drives. Because they have no moving parts, SSDs are also much quieter than hard disk drives. However, SSDs are also significantly more expensive than hard disk drives. For this reason, if a device needs large quantities of storage, it may be more cost-effective to use hard disk drives. However, if the device needs to be able to access data quickly, be durable, or be compact in size, manufacturers may use a SSD. The vast majority of modern laptop and notebook computers, as well as tablet computers, use an SSD as their main memory drive, augmented by a removable mini- or micro-SSD card.

Some computers utilize external memory sources. These are drives located outside the device. If it is connected to the device by a universal serial bus (USB) cable or other interface, it is called an external hard drive. External hard drives are easily transferable from one device to another, making them useful for quickly moving large media files. They may also be used to back up large amounts of important files, protecting them from computer malfunction or viruses.

If the external memory is accessed through the internet, it is referred to as “the cloud.” Many services offer large amounts of external memory for purchase. This may be used for server backups, media storage, or any number of other applications. Cloud storage allows users to expand the storage capacity of their machines without making any physical alterations to the computers. The cloud also features many of the same benefits as an external hard drive. Files can easily be relocated to a new machine in the event of a hardware or software failure. Additionally, renting server space from a cloud storage service may be cheaper than purchasing and installing additional physical storage devices. Service providers such as Google and Yahoo!, and many others, allow a limited amount of free storage for their public users.

FURTHER READING

1 

Claerr, Jennifer. “What Are the Four Basic Functions of a Computer?” Techwalla, www.techwalla.com/articles/what-are-the-four-basic-functions-of-a-computer.

2 

“Data Measurement Chart.” University of Florida, www.wu.ece.ufl.edu/links/dataRate/DataMeasurementChart.html.

3 

“Hard Drive.” Computer Hope, www.computerhope.com/jargon/h/harddriv.htm.

4 

“How Computers Work: The CPU and Memory.” University of Rhode Island, homepage.cs.uri.edu/faculty/wolfe/book/Readings/Reading04.htm.

5 

Subhash, D. “Types of Memory.” IT4NextGen, 27 Aug. 2016, www.it4nextgen.com/computer-memory-types.

6 

“Timeline of Computer History.” Computer History Museum, www.computerhistory.org/timeline/computers/.

7 

Webb, David. “All About the Computer Memory: Definition, Types.” CCM Benchmark Group, 19 Oct. 2022, ccm.net/computing/hardware/10069-introduction-to-memory/.

8 

Zimmerman, Kim Ann. “History of Computers: A Brief Timeline.” Live Science, 8 Sept. 2015, www.livescience.com/20718-computer-history.html.

See also: Binary Pattern; Client-Server Architecture; Computer Networks; Computer Engineering; Computer Software; Cyberspace; Data Analytics (DA); Digital Logic; Domain-Specific Language (DSL); Graphene; Human-Computer Interaction; Magnetic Storage; Optical Storage

Citation Types

Type
Format
MLA 9th
Biscontini, Tyler. "Computer Memory." Principles of Robotics & Artificial Intelligence, Second Edition, edited by Richard M. Renneboog, Salem Press, 2023. Salem Online, online.salempress.com/articleDetails.do?articleName=PORobot2e_0047.
APA 7th
Biscontini, T. (2023). Computer Memory. In R. M. Renneboog (Ed.), Principles of Robotics & Artificial Intelligence, Second Edition. Salem Press. online.salempress.com.
CMOS 17th
Biscontini, Tyler. "Computer Memory." Edited by Richard M. Renneboog. Principles of Robotics & Artificial Intelligence, Second Edition. Hackensack: Salem Press, 2023. Accessed December 14, 2025. online.salempress.com.