Is your memory more like that of an elephant or a sieve? There are plenty of people who compare themselves to these things, but it is rare to hear someone declare their memory is comparable to one. One reason for this is because human brains and computer memories serve very distinct functions and work in very different ways. But it also reflects the fact that computer memories are the closest thing we have to memory perfection, when we humans often struggle to remember names, faces, and even the day of the week. How do these “amazing rememberers” actually operate, and what is their secret? What do you think? Let’s investigate!
Photo: An integrated circuit, such as this computer memory chip, is an example. That means it’s a collection of thousands of electronic pieces (components) on a small silicon chip the size of a pinkie nail. This is a USB memory stick’s 1-gigabit NAND flash memory chip.
What is memory?
Illustration: Although it is not possible to teach a computer to remember things in the same way that a human brain does, it is possible to teach a computer to recognize patterns and recall things in a manner that is similar to how a brain does it by utilizing something that is called a neural network. Jan Stephan van Calcar, who collaborated closely with the pioneering anatomist Andreas Vesalius, created this historic picture of the brain’s anatomy around the year 1543.
Memory, whether it be human or computer, serves the fundamental function of maintaining a record of information for a set amount of time. The ability of the human memory to forget things is one of the most striking characteristics of this particular form of storage. If you don’t take into account the fact that our ability to focus on multiple things at once is limited, that might sound like a huge flaw. That is to say, forgetting is most likely a sophisticated strategy that humans have evolved to help us focus on the things that are instantly relevant and crucial in the midst of the endless chaos of our everyday lives — a means of concentrating on what really counts. When you forget something, it’s like cleaning out your closet so you can create place for new things to come in.
In contrast to human brains, computers do not remember or lose information in the same way that we do. Computers operate using a binary system, which is detailed in greater detail in the next box: they either know something or they don’t, and once they’ve learnt something, they generally don’t forget it unless there is some kind of catastrophic failure. People are unique among animals. We could be able to identify things (like “I’ve seen that face before somewhere”) or have the impression that we know something (like “I remember studying the German term for cherry when I was in school”) even if we are unable to recall specific details about such things. Memory in humans, as opposed to computers, can be forgotten, then remembered, then forgotten, and so on, giving the impression that it is more closely related to art or magic than it is to science or technology. When smart people master strategies that enable them to memorize thousands of pieces of information, they are celebrated as though they were great magicians. This is the case despite the fact that what they have accomplished is much less impressive than anything a USB flash memory stick that costs five dollars could do!
The two types of memory
Memory is something that both human brains and computers share, although they also have their own unique flavor. The human memory is actually composed of two distinct parts: a “working” memory that is short-term and stores information that we have recently seen, heard, or processed with our brains, and a “long-term memory” that stores information that we have learned, events that we have experienced, things that we know how to do, and so on, that we generally need to remember for much longer. The typical personal computer also incorporates two distinct forms of memory within its design.
There is a main memory that is built in, sometimes referred to as internal memory, and it is comprised of silicon chips (integrated circuits). Since it is able to store and retrieve data (information that has been processed) relatively quickly, it is utilized to assist the computer in processing whatever it is currently working on. In most cases, the contents of the device’s internal memory are lost as soon as the power is turned off because the memory is considered to be volatile. Because of this, computers also include something that is referred to as auxiliary memory (or storage), which remembers items even when the power is disconnected from the device. The supplementary memory of a standard personal computer (PC) or laptop is typically supplied by either a hard drive or a flash memory device. Because it was often located in a completely different machine that was connected to the main computer box by a cable in older, larger computers, auxiliary memory is sometimes referred to as external memory. Plug-in hard drives, CD/DVD ROMs and rewriters, USB flash memory sticks, and SD memory cards (which can be inserted into devices such as digital cameras) are some examples of the types of auxiliary storage that are commonly available in today’s personal computers. In a similar vein, modern PCs frequently come equipped with USB flash memory sticks and SD memory cards.
A couple of samples of supplemental memory can be seen in this photo in the form of hard disks. On the left, we have a hard drive for a PCMCIA iPod card that is 20 gigabytes in capacity. On the right, there is a somewhat larger hard drive taken from a laptop that has 30 GB of storage space. When compared with the 256 MB flash memory chip shown in the top shot, the capacity of the 30 GB hard drive is almost 120 times more. You can view more images like this one on the primary article we have on hard drives.
In everyday use, the line separating main memory and auxiliary memory can become a little hazy at times. Main memory in computers normally only has a certain amount of space available (typically somewhere between 512MB and 4GB on a modern computer). When individuals have more resources available to them, they are able to process information more swiftly and complete tasks more rapidly. If a computer needs to store more information than its main memory has room for, it can temporarily relocate less important stuff from the main memory onto its hard drive in what is known as a virtual memory in order to free up some space. In this way, the computer is able to store more information. When this occurs, you will hear the hard drive clicking away at a very high pace as the computer reads and writes data between its virtual memory and its real (main) memory. This is because the computer reads and writes data back and forth between these two memory locations. Utilizing virtual memory is a technique that is significantly slower than using main memory. As a result, using virtual memory will really slow down your computer. This is because accessing hard drives takes more time than accessing memory chips. That’s basically the reason why computers with greater memory work so much more quickly.
Photo: The vast majority of memory chips are two-dimensional, and the transistors (electronic switches) that are used to store information are arranged in a grid on the surface of the chip. In contrast, the transistors that make up this 3D stack memory are not only organized horizontally, but also vertically; this allows for a greater quantity of data to be stored in a given volume of room. This image was provided by the NASA Langley Research Center (NASA-LaRC).
RAM and ROM
The components that make up the memory found inside a computer are known as ROM and RAM, which stand for read-only memory and random access memory, respectively (read-only memory). RAM chips are used to save anything a computer is working on in the very short term because they only remember things while the computer is powered on. Because of this limitation, RAM chips are utilized for this purpose. On the other hand, ROM chips are able to remember things regardless of whether or not the power is on. They are given information at the manufacturer before being preprogrammed with it, and then they are used to store things like the computer’s BIOS, which is the basic input/output system that controls fundamental aspects of the computer like the screen and the keyboard. Do not be concerned if the terms random access memory (RAM) and read-only memory (ROM) appear to be confusing since, as we will see in a moment, their names are not the clearest in the world. Just keep in mind this important fact: the main memory found inside of a computer is built on two different kinds of chips: a temporary, volatile kind that remembers only while the power is on (RAM), and a permanent, nonvolatile kind that remembers whether the power is on or off (ROM).
The memory storage capacity of early home computers is dwarfed by that of modern devices. This table illustrates the typical amounts of random access memory (RAM) found in Apple computers, ranging from the very first Apple I computer, which was released in 1976, to the iPhone 12 smartphone, which was released more than four decades later and has approximately 500,000 times more RAM onboard! These are only some preliminary comparisons based on the assumption that one KB is equivalent to approximately one thousand bytes, one MB is equivalent to approximately one million bytes, and one GB is equivalent to approximately one billion bytes. Because in the field of computer science, one kilobyte is equal to 1024 bytes, the terms kilobyte (KB), megabyte (MB), and gigabyte (GB) might be rather confusing. Don’t worry about it; it won’t make much of a difference in the comparisons that we made earlier.
Random and sequential access
This is where things can get slightly confusing. RAM has the name random access because (in theory) it’s just as quick for the computer to read or write information from any one part of a RAM memory chip as from any other. (Incidentally, that applies just as much to most ROM chips, which you could say are examples of nonvolatile, RAM chips!) Hard drives are also, broadly speaking, random-access devices, because it takes roughly the same time to read information from any point on the drive.
Random access memory is just one type of computer memory; there are others. In the past, it was usual practice for computers to save data on separate machines referred to as tape drives, which employed lengthy spools of magnetic tape to do so (like giant-sized versions of the music cassettes in old-fashioned Sony Walkman cassette players). If the computer wanted to access information, it had to spool backward or forward through the tape until it reached exactly the spot it wanted. This was analogous to how you had to wind back and forth on a tape for a significant amount of time in order to locate the track you wanted to play. There was quite a delay while waiting for the tape to spool forward to the proper point if it was exactly at the beginning of the tape but the information the computer sought was at the very end of the tape. If the tape occurred to be located in the correct location, the computer would have almost instantaneous access to the information it was looking for. Tapes are an example of sequential access: information is stored in sequence, and the amount of time it takes to read or write a piece of information depends on where on the tape the read-write head (the magnet that reads and writes information from the tape) happens to be in relation to the tape at any given moment.
DRAM and SRAM
DRAM, which stands for dynamic RAM, and SRAM, which stands for static RAM, are the two primary types of RAM (static RAM). The majority of the internal memory found in personal computers, gaming consoles, and other electronic devices is made up of DRAM since it is both more affordable than SRAM and has a higher density (the ability to pack more data into a smaller space). Because of its higher cost and lower density, SRAM is more likely to be utilized in the temporary, smaller “working memories” (caches) that are a component of a computer’s internal or external memories. SRAM is also quicker than DRAM, which uses less power overall. It is also commonly employed in portable gadgets such as telephones, where it is vitally critical to minimize the amount of power consumed (and maximize the amount of time a battery can last).
The way in which DRAM and SRAM are assembled from their constituent electronic parts is what gives birth to the distinctions between the two types of memory. The dynamic random access memory (DRAM) differs from the static random access memory (SRAM) in that it requires power to be periodically sent through it in order to maintain the integrity of its memory, but the static RAM does not require “refreshing” in the same sense. Because it only requires one capacitor and one transistor to store each bit (binary digit) of information, DRAM is more dense than SRAM, which requires many transistors for each bit. This allows DRAM to store more information in the same amount of space occupied by the memory.
As is the case with RAM, read-only memory (ROM) can come in a number of distinct flavors, and contrary to popular belief, not all of these flavors are exclusively read-only. The flash memory that is used in USB memory sticks and memory cards for digital cameras is a type of ROM that can store information virtually eternally, even while the power is off (similar to traditional ROM), but it can still be reprogrammed reasonably simply anytime it is required to do so (more like conventional RAM). To talk in more technical terms, flash memory is a sort of EEPROM, which stands for electrically erasable programmable ROM. This means that information can be recorded or erased relatively easily by simply running an electric current across the memory. You could be thinking, “Hmmm, that’s an interesting thought, but doesn’t all memory work in the same manner… by flowing electricity through it?” Yes! However, the name actually alludes to the fact that erasable and reprogrammable read-only memory (ROM) used to operate in a different fashion than it does today. In the 1970s, the erasable and rewritable read-only memory (ROM) technology known as EPROM was the most widely used (erasable programmable ROM). To delete the information stored on EPROM chips, a procedure that was both laborious and inconvenient had to be used. This approach involved first disconnecting the chips from their circuit and then subjecting them to intense ultraviolet light. Imagine if you had to go through that tedious process each time you wanted to store a fresh series of images on the memory card of your digital camera. It would be a real pain.
In many modern electronic devices, such as mobile phones, modems, and wireless routers, the software is typically stored not on ROM, as one might anticipate, but rather on flash memory. This implies that you may quickly update them with new firmware (software that is stored relatively permanently in ROM), whenever an upgrade becomes available, by using a procedure that is referred to as “flashing.” If you’ve ever upgraded the firmware on your router or copied a large amount of information to a flash memory, you may have noticed that flash memory and reprogrammable ROM operate more slowly than traditional RAM memory. Additionally, it takes longer to write to these types of memories than it does to read from them.
Hard drives, CD/DVD ROMs, and solid-state drives (SSDs), which are comparable to hard drives but store information on massive amounts of flash memory instead of spinning magnetic discs, are the most often utilized supplementary memory in current PCs.
But throughout the long and intriguing history of computers, people have utilized a wide variety of alternative memory devices, the majority of which stored information by magnetizing items. This was done in order to preserve data. Information was typically stored on floppy disks by floppy drives, which were common from roughly the late 1970s through the middle of the 1990s. These were small, thin rings of plastic coated with magnetic substance and rotating inside long-lasting plastic casings. The cases started off around 8 inches in diameter and progressively shrunk to 5.25 inches, then 3.5 inches, and finally settled at approximately 3.5 inches as the most popular size. Zip drives were very similar to conventional hard drives, but they were able to store significantly more data in a highly compressed format within bulky cartridges. During the 1970s and 1980s, microcomputers, which were the precursors to today’s personal computers, typically saved data using cassette tapes. These tapes were identical to the ones that people used at the time to play music. It may come as a surprise to learn that huge computer departments continue to make extensive use of tapes as a means for backing up data in the modern era. The primary reason for this is that the process is both straightforward and low-cost. It doesn’t matter if tapes run slowly and sequentially while you’re using them for backups since in most cases, you want to replicate and restore your data in a very systematic way—and time isn’t always all that crucial in these situations.
Moving even further back in time, computers from the 1950s and 1960s recorded information on magnetic cores, which were small rings made from ferromagnetic and ceramic material. Even earlier machines stored information using relays, which are switches like the ones used in telephone circuits, and vacuum tubes (a bit like miniature versions of the cathode-ray tubes used in old-style televisions).
Digits, or numbers, are the primary form of information storage and processing in computers. This applies to all types of data, including images, videos, text files, and sound. This is the reason why some people refer to them as digital computers. Work with numbers in the decimal system (base 10) is most comfortable for humans (with ten different digits ranging from 0 through 9). On the other hand, computers use a whole other number system known as binary, which consists of just two numbers—zero (0) and one (1)—to perform their calculations (1). In the decimal system, the columns of numbers correspond to ones, tens, hundreds, thousands, and so on as you walk to the left; however, in the binary system, the identical columns represent powers of two. In the decimal system, you step to the left to go from one to 10. (two, four, eight, sixteen, thirty two, sixty four, and so on). Therefore, the decimal number 55 is converted to binary as 110111, which is equal to 32 plus 16 plus 4 plus 2 plus 1. When you want to save a number, you’ll need a lot more binary digits, which are also called bits. You are able to store any decimal value from 0 to 255 with eight bits, which is commonly referred to as a byte. This corresponds to the binary range of 00000000 to 11111111.
People have 10 fingers, which lends itself well to the representation of decimal numbers. There are only eight fingers on a computer. Instead, they use something called transistors, which are electronic switches that can number in the thousands, millions, or even billions. When electric currents move through transistors and turn them on and off, the numbers that are stored in those transistors are binary. When a transistor is turned on, it stores a one; when it is turned off, it stores a zero. A computer’s memory is able to store decimal numbers by turning off a complete series of transistors in a binary pattern, much like someone would do by holding up a series of flags. This allows the computer to store decimal numbers. The number 55 can be conceptualized as following the pattern of holding up five flags while lowering one of them:
Artwork: The number 55 in decimal corresponds to the binary representation of (1/32), (1/16), 0/8, 1/4, 1/2, and 1/1, which is 110111. Although there are no flags contained within a computer, it is nonetheless able to remember the number 55 by using six transistors that are toggled on and off in the same manner.
Therefore, storing numerical values is simple. But how is it possible to do mathematical operations such as addition, subtraction, multiplication, and division utilizing only electric currents? You will need to make use of these smart circuits known as logic gates, which you can learn more about by reading our article on logic gates.
A brief history of computer memory
Artwork: IBM’s original hard drive from its 1954/1964 patent. You can see the multiple spinning discs, highlighted in red, in the large memory unit on the right. Artwork from US Patent 3,134,097: Data storage machine by Louis D. Stevens et al, IBM, courtesy of US Patent and Trademark Office.
Here are just a few selected milestones in the development of computer memory; for the bigger picture, please check out our detailed article on the history of computers.
1804: Joseph Marie Jacquard uses cards with holes punched into them to control textile-weaving looms. Punched cards, as they’re known, survive as an important form of computer memory until the early 1970s.
1835: Joseph Henry invents the relay, an electromagnetic switch used as a memory in many early computers before transistors are developed in the mid-20th century.
19th century: Charles Babbage sketches plans for elaborate, gear-driven computers with built-in, mechanical memories.
1947: Three US physicists, John Bardeen, Walter Brattain, and William Shockley, develop the transistor—the tiny switching device that forms the heart of most modern computer memories.
1949: An Wang files a patent for magnetic core memory.
1950s: Reynold B. Johnson of IBM invents the hard drive, announced to the public on September 4, 1956.
1967: IBM’s Warren Dalziel develops the floppy drive.
1960s: James T. Russell invents the optical CD-ROM while working for Battelle Memorial Institute.
1968: Robert Dennard of IBM is granted a patent for DRAM memory.
1981: Toshiba engineers Fujio Masuoka and Hisakazu Iizuka file a patent for flash memory.
See more :