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Wednesday, January 8, 2020

What is Memory in a Computer




Computer memory can be defined as a physical device to store information either temporarily or permanently in a computer. Computer memory is a generic term used to describe all the different forms of technology that a computer may use. These forms of memory include, but are not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), and Flash memory. The different types of computer memory are designed to perform various tasks, which implies significant differences in their performance and design. A practical example would be RAM that is designed to be very fast, which means that the central processing unit (CPU) can access data stored in it very quickly. However, the ROM is designed to be economical (low cost), meaning that it is designed to store large amounts of data stored there at relatively meager costs. 

A memory is like a human brain. Just like the brain, it is used to store instructions and data. Computer memory is essentially a storage space where data is processed, and computer instructions required for processing are stored. The computer memory is usually subdivided into several tiny parts called cells. Every cell or location has a unique address. These addresses range from 0 to the maximum memory size number minus 1. For instance, if the computer memory has 64k words, this memory unit has 64*1024 = 65536 memory cells/locations. So, in this case, the unique addresses of these computer cells will vary from 0-65535.

In computing, however, the term computer memory is generally used to refer to the RAM. The computer typically uses the RAM to run its programs and operating system. It keeps the data nearby for easy and fast access by the CPU. For instance, when you - a computer user - open an image or video file on your computer for viewing and later on feels the need to open word, you will minimize the image window. The RAM will still store the file as open until you close the window permanently. This scenario depicts the importance of RAM. A computer with good RAM (type and amount) will run multiple programs simultaneously and faster. Therefore, good RAM impacts the speed and power of the machine.

How can I check Memory on my Computer?

As earlier mentioned, memory is commonly used to refer to the RAM. Checking the RAM in your computer is a short and simple process. Here is a quick procedure on how to check the memory on a windows 10 computer.

Press the Windows Key + R on your keyboard to open the Run dialogue box. The Run program will prompt you to enter the name of the program you wish to open. For example, enter “dxdiag” and press Enter. Next, windows will open a direct X Diagnostic Tool window that contains assorted information about your computer. Under the “Systems” Tab, check for memory. In my case, it shows 8192 MB RAM, which implies that my machine has 8 GB RAM. Here is a screenshot of the dialogue box you should expect to see.

What is Memory in a Computer

The Basics of Computer Memory

Even though computer memory is technically any form of electronic storage, it is often used to identify temporary, fast types of storage. Imagine how fast your computer would be if it had to access the hard drive every time to retrieve all pieces of data. You could probably guess it would be prolonged, right? When the information is stored in the memory, the CPU will access it quickly, increasing the overall operation speeds of the computer. Most forms of computer memory are designed to store data temporarily. 

The CPU is always in constant communication with the memory between power and shut down. However, the CPU accesses memory according to a very distinct hierarchy. Information either comes from permanent storage devices like hard drives or input devices like the keyboard. Both of these types of information go into RAM first.  Subsequently, the CPU stores small chunks of data that it will require to access, mostly in the cache, and maintains particular instructions in the register.



Types of Computer Memory

Computer memory is primarily subdivided into three types- 

Cache memory

This is an extremely high-speed semiconductor memory with the ability to increase the speed of the CPU. Typically, it acts as a buffer between the primary memory (main memory) and the CPU. The computer uses cache memory to store the most frequently used pieces of data and programs by the CPU. The operating system is responsible for transferring these applications and data from the disk to the cache memory. From the cache memory, the CPU accesses the information easily and quickly.

Advantages of Cache memory

  • Cache memory is high-speed
  • The CPU uses less access time 
  • It stores information or programs that can be executed within a short time.
  • It stores data temporarily

Disadvantages 

  • It has minimal capacity
  • It is expensive

Primary memory

This memory is also known as the main memory. It is used to hold only those data and instructions that the machine is working on. In this memory, data is lost immediately if power is lost, and it is typically made of a semiconductor type of device. Therefore, these memories are not the fastest. The primary memory is subdivided into RAM and ROM.

Major Characteristics of Primary Memory

  • The data stored is lost in case of any power loss
  • It is faster than secondary memory
  • It is usually volatile memory
  • It is a semiconductor memory
  • All computers require primary memory to run

Secondary memory

This type of memory is commonly known as external memory or non-volatile memory. Among the three, it is the slowest. Secondary memory is used for storing information/data permanently. The CPU cannot directly access these memories; rather, the CPU uses input/output routes to access them. Typically, the information stored in the secondary memory is first transferred to the primary memory before the CPU can access it. Some examples of secondary memory devices are DVD, external hard drives, Flash drives, and CD-ROM. The hard drive shown below is an example of secondary memory.

What is Memory in a Computer

Major Characteristics of Secondary Memory

  • They are non-volatile memories
  • Computers can run without secondary memory
  • It is sometimes known as backup memory
  • They are optic and magnetic memories
  • They are slower than primary memories

How does Computer Memory work?

All components in your computer work in unison to make sure your machine runs smoothly. The CPU, the operating system, and the hard drive work collaboratively with the memory. Memory is one of the most vital parts of this team. As soon as you turn on your computer, your CPU will continuously communicate with the memory until you shut it down. 

Here is a typical scenario explaining how memory is involved in the normal operations of a computer.

When you press the power button and turn on the computer, the computer will immediately load data from the ROM and perform a power-on self-test (POST). The POST is essential in ensuring that all the main components of the computer are functioning correctly. During the POST process, the memory controller runs a check on all the memory addresses using a quick read/write operation to ensure that errors are not occurring in the memory chips. After that, the computer then executes the basic input/output system (BIOS) from ROM. The purpose of the BIOS is to provide fundamental information regarding storage devices, security, boot sequence, auto device recognition (plug and play capability), and many others. Immediately after, the computer attempts to load the operating system (OS) in the hard drive (ROM) into the RAM. Usually, critical parts of the OS are temporarily stored in the RAM when the machine is on. The computer does this to improve the functionality and performance of the system.

If you run a specific program or application on the computer, it is loaded into RAM. To prevent overworking the RAM, several applications load only the vital parts of the program to the RAM and then load the others later.  All the files that are part of that program are loaded into the RAM. Finally, when you decide to save a file and exit the application, the specific file is written to the specified location. It is after this that the file and the application are purged from the RAM.

Conclusion

Computer memory refers to any device used by the computer to store information or data either temporarily or permanently. However, in the computing world, the term usually means RAM. Therefore, memory is an essential part of the computer ecosystem since computers cannot run without memory (RAM).

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