AN INTRODUCTION TO MEMORY TECHNOLOGIES

In today's fast-paced and tech-savvy world, computers and phones have become an essential part of our life. We can't imagine surviving without them. But have you ever wondered how these tiny, portable devices perform numerous, complicated tasks in microseconds? Well, the answer is they use a complex network of functions working in a union. For example, when we study complex mathematical and historical facts, that information gets stored in our brain. Similarly, when we talk about computers, it carries out complex operations on a much larger scale than humans cannot simply do. Such operations are carried out by digital memories that help them store data.

In computers, memory is the most essential component for the normal functioning of any system – to store data, to perform calculations, to do complex operations, etc. We know that almost all our information and data is stored in the Hard Disk within the CPU. The Hard Disk/Hard Drive/Hard Disk Drive has the most extensive memory in the computer system. But a lot of important data of a computing device is stored in what we will study in this article known as primary memory.

In this blog, we will uncover different types of memories that make these instantaneous and simultaneous calculations possible, how this technology is evolving rapidly to keep up with our ever-growing data and speed needs as well as taking a quick look at the performance, factors responsible for the advancement of the various memory technologies.

Before getting into a brief discussion of the various memory technologies let's understand what is meant by “Memory”? Memory is a main component of the digital system. Memories are used to store the data within the system. Every system needs memory to store the data and process the data to complete its operation successfully. The memory and storage system is a critical component of various computer systems. It is a hierarchy of memory and storage devices with various capacities, costs, and access times.

A few questions that might rise up in your mind could be that is it worth going through a lot of gigabytes of memory to browse one piece of information? Or what does the hard disk comprise of - is it efficient to access the entire hard disk for a small amount of information. These are all great questions, and if these thoughts spring up in your mind, kudos to your thought process. Well, we will try to answer all of these questions while listing out the information below. Let’s start off first with the various types of memory technologies.

Classification of Memory Technologies

Primary Memory

Primary Memory is also known as system memory. It is considered the main memory of the computer. The Primary memory is located close to the Central Processing Unit (CPU)on the motherboard. This proximity enables the CPU to access information immediately. The processor thus gets an immediate response to any information needed, without much delay. These are expensive but very fast compared to secondary memory. As well as Primary memory is both a volatile and non-volatile memory.

The two key types of primary technology, that are discussed further are as follows:

ROM

ROM stands for read-only memory, and the name stems from the fact that while data can be read from this type of computer memory, data cannot normally be written to it. In view of this, it is used where data needs to be stored permanently, even when the power is removed - many memory technologies lose the data once the power is removed.

Image courtesy: https://www.thoughtco.com/definition-of-rom-958317

ROM may be a sort of non-volatile memory, which suggests that the info stored in ROM persists within the memory even when it receives no power – for instance when the computer is turned off. In order for a ROM chip to function correctly, it is very important that its programming be completely perfect and it is also important to have complete data with it when the chip is being created. This is because you cannot reprogram or rewrite a standard ROM chip again. The data which is stored permanently on personal computers and other electronic devices like smartphones, tablets, TV, AC, etc. are also an example of ROM.
As a result, this sort of semiconductor memory technology is widely used for storing programs and data that has got to survive when a computer or processor is powered down. For example, when the computer turns on the CPU starts reading information without any use of complex software or need of drivers. The ROM usually contains a bootstrap code which is that the basic set of instructions a computer must perform to become conscious of the OS stored in secondary memory and to load parts of the OS into primary memory in order that it can start-up and become able to use.

RAM

As the names suggest, the RAM or random access memory is a form of semiconductor memory technology that is used for reading and writing data in any order i.e. accessing the data randomly. 
The most important thing to understand about RAM is that RAM memory is a very fast technology, it can be written well as read. It is a volatile memory (so all data stored in RAM memory is lost when it loses power).

The data to be accessed and modified is moved to RAM, where it gets processed extremely quickly in order to keep the CPU functioning properly. When the data is no longer required it is shunted out to slower but cheaper secondary memory and the RAM space that has been freed up is filled with the next chunk of data that is about to be used. Hence, the larger the amount of memory a computer has, the more software and programs it can run and improve the efficiency of the PC.

Finally, it is very expensive compared to all types of secondary memory in terms of cost per gigabyte. It is because of the relatively high cost of RAM compared to secondary memory types that most computer systems use both primary and secondary memory.

Image courtesy: https://technobyte.org/memories-digital-electronics/

Since the RAM has such an important role to play, the amount of memory it holds has a lot of significance. If a computer does not have much memory to boot the OS and handle the programs running on it, it will affect the performance and make the system slower. Hence, the larger the amount of memory a computer has, the more software and programs it can run and improve the efficiency of the PC. 

Random-access memory is employed in huge quantities in computer applications as current-day computing and processing technology requires large amounts of memory to enable them to handle the memory-hungry applications used today. Many types of RAM including SDRAM with its DDR3, DDR4, and shortly DDR5 variants are utilized in huge quantities.

As can be seen, these two types of memory are very different, and as a result, they are used in very different ways. Each of the memory technologies outlined below falls into one of these two types of categories. Each technology offers its own advantages and is employed in a particular way, or for particular applications.

Secondary Memory

The Secondary Memory is called Storage. The Secondary memory is physically located within distinct storage devices, such as a hard-disk drive (HDD) or a solid-state drive (SSD). Secondary memory is considered to be a non-volatile memory. The data cannot be accessed directly by the processor. It is first copied from secondary memory to primary memory. It can only be then accessed by the CPU. 

While secondary memory is much slower than primary memory, it typically offers far greater storage capacity. For example, a computer may have a one terabyte hard drive, but only 16 gigabytes of RAM. That means the computer has roughly 64 times more secondary memory than primary memory.

Some secondary memory devices available are a hard-disk drive(HDD), CD/DVD drive as well as a pen-drive.

Hard-disk drive(HDD)

Image courtesy: https://www.enterprisestorageforum.com/storage-hardware/hard-disk-drives.html

More info: What is volatile non-volatile memory?

Volatile memory is memory that needs power to take care of the stored information. It is also referred to as temporary memory. The data within the volatile memory is stored till the system is capable of it, but once the system is turned off the data within the volatile memory is deleted automatically.
Whereas, Non-volatile memory is memory which will retain the stored information even when not powered. It’s not economical and slow in fetch/store as compared to volatile memory however stores a better volume of knowledge . All such information that must be stored for an extended amount of your time is stored in non-volatile memory. Non-volatile memory features a huge impact on a system’s storage capacity.

Thank you for reading this blog! For more info on different types of RAM and ROM, refer to the article "Types of RAM and ROM" on this blog

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The contributor to this article is Arya Patil.

References

• Memories using in Digital System Design, IRJT e-ISSN: 2395-0056Volume: 07 Issue: 05 | May 2020 - https://www.researchgate.net/publication/341453150_Memories_using_in_Digital_System_Design
• Types of computer memory - https://www.enterprisestorageforum.com/storage-hardware/types-of-computer-memory.html
• https://en.wikipedia.org/wiki/Static_random-access_memory
• https://technobyte.org/memories-digital-electronics/