Computer Storage Devices
What is a computer storage device?
A storage device, sometimes referred to as storage media, is a hardware device used for storing data in computers which is one of the most crucial components in modern computers and all data stored in a computer exists in the binary form. Storage devices can be classified in different ways and they are available as both internal and external devices. However they can be mainly classified as primary storage devices and secondary storage devices. A standard personal computer includes a number of storage devices such as the RAM, Cache memory, and Hard Disc. Storage devices can be used to permanently or temporally store data and information and they have evolved from Punch cards to what we use commonly and widely use today which are solid-state devices, abbreviated as SSDs. There is a wide range of storage devices available today to meet the altering storage facility requirements such as speed, space and affordability due to the rapidly developing technology and as technology upgrades, the storage devices need to be upgraded in parallel as well. (hope, 2021)
The usage of computer storage devices
Although technically the computer can function without storage devices, it will only have the ability to view and read data as it does not have the power to remember any data. Therefore to complete even a simple task such as browsing the internet to access information, the computer needs memory as information has to be stored somewhere. Since we need to store a massive quantity of data permanently without the risk of data loss, storage devices are essential to the computer. The main purpose of storage devices is retaining information which means storing data and programs permanently or temporally in the computer but storage devices also help to extract and retrieve data (Hope, 2020)
Types of storage
Storage devices can be classified into various categories based on capacity, speed and affordability. A main way of classifying storage devices is based on its permanence.
Primary storage
Primary storage, also referred to as the main memory or the internal memory in a computer is the memory that allows the computer to manipulate data, programs and instructions temporally at the moment the computer is working. Primary storage is directly or indirectly connected to the Central Processing Unit by a memory bus and is located in the motherboard which results in primary storage being extremely fast because it’s less time consuming to access all the necessary data and information from the main memory. However the capacity of the primary storage is restricted and the primary storage today in a standard personal computer is 4GB. The information and instructions from the secondary memory has to go through the main memory as well. The Central Processing Unit is responsible for reading and executing instructions stored in the main memory. (Thakur, 2021)
The main and most common types of primary storage are
· RAM
· ROM
· Cache memory
RAM
· RAM is Random Access Memory is a volatile memory which means the data remains in the memory only as long as the power is on and the data is lost when the power is off.
· RAM is also sometimes called as main memory, system memory and primary memory itself.
· RAM allows continuous and simultaneous read and write.
· RAM merely focuses on instantaneous tasks due to the lack of permanence and in the modern day, the RAM takes the shape of integrated circuit chips.
· RAM doesn’t exceed a memory limit as it refreshes the memory from moment to moment.
· RAM has the ability to access and retrieve data from any specific location as needed
· The quantity of RAM installed is directly associated with the performance and speed of the computer.
(Thakur, Different Types of RAM? Explain in Detail- Computer notes, 2021)
There are two types of RAM
· SRAM
· DRAM
The differences between the two
ROM
· ROM stands for Read Only Memory which defines any memory media that can only be read.
· This is the type of memory that is used when then computer starts to boot up (BIOS)
· The ROM has the ability to contain permanent and semi-permanent data
· Since the ROM is non-volatile, data will not be lost even when the power of the computer is turned off.
· Although ROM is supposed to be read, there is permission to perform rewriting for a certain restricted level.
· There is the possibility of upgrading firmware like BIOS with the usage of software without actually having to physically replace the chips but cannot be easily overwritten or modified.
· Firmware that contain instructions to perform some of the most basic operations that are needed to operate hardware is stored in the ROM.
· ROM can be further classified into four types.
.Cache Memory
· Cache memory is a memory system that stores most frequently and commonly used data temporally in order to allow faster access by the Central Processing Unit.
· The cache memory is a segment of the computer’s main memory and therefore uses semiconductor based transistor circuits.
· Majority of the modern computers contain L3 and L2 caches while the older ones have used L1.
· The limited capacity of cache memory helps to minimize the time taken to place and process data.
(Thakur, What is Cache Memory | Types of Cache Memory- Computer Hopes, 2021)
Secondary storage
Secondary storage, also commonly known as external memory and auxiliary storage, is internal or external non-volatile and long term storage commonly used by computers and because of secondary storage, the data is not erased or lost as the power goes out. However, computers can function without secondary sources and all computers do not need secondary storage, specifically embedded systems such as the computer system in a washing machine because data does not have to be saved when the power is off. Secondary storage is not directly accessed by the CPU, instead computers utilize primary storage as an intermediate medium through which secondary storage can be accessed by input and output channels to transfer the necessary data and information. (Bitesize, 2021)
There are three main types of secondary storage devices
Hard-disk drives
· The hard-disk drive is the main and generally the largest storage device in a computer
· The hard-disk has the capacity to store data anywhere from 160 gigabytes to 2 terabytes.
· A hard-disk speed refers to the speed of reading and writing on a hard-disk while a hard-disk unit consists of a set rotation speed anywhere from the range of 4500 to 7200 rpm.
· The unit of measuring the time it takes to access the disk is milliseconds.
· The medium of a magnetic disk holds iron particles which have the ability to be polarized in either directions under the influence of a magnetic charge which are created by the usage of read and write heads containing electromagnets.
Tertiary storage
Tertiary storage refers to data archives which consist of a massive capacity that can contain extensive amounts of data and it also contains a mechanism to mount and dismount mass removable media. This particular system is comparatively slower and therefore is not utilized in situations where frequent access is required. Tertiary storage is mainly useful when dealing with enormous amounts of data. Tertiary storage is shelves specifically organized for them and contain a particular amount of robotic mechanisms for transferring data without the need of involvement by man. (Maciej Brodowicz, 2018)
Types of Tertiary Storage
Offline storage
Offline storage, also known as disconnected storage. This unit is not under the control of the processing unit as this is externally accessed. It must be connected externally by an individual.
Following are some of the examples
Floppy disk
· A floppy disk is soft magnetic disk that is portable. Floppy disks have a much smaller storage capacity in comparison to hard disks, their access rate is slow but they are much less expensive as well.
· A floppy disk can store data up to 1.44 MB and the two common sizes are 5 1/4 and 3 ½
Zip diskette
· This is a hardware storage device developed by Iomega that has the ability to function like a standard 1.44.
· Has the capability of containing from 100MB to 250MB on new drives.
· Now is very less popular among the public due to the availability of many other storage devices with much larger capacity.
Types of computer storage devices
Secondary storage types can be divided into main three categories based on different aspects such as their technology and usage.
Magnetic storage devices
· Magnetic storage devices “use magnetic fields to magnetize tiny individual sections of a metal spinning use magnetic fields to magnetize tiny individual sections of a metal spinning disk”.
· Each individual segment of such a disk represents a single bit. The binary 1 is represented by a magnetized section while the binary 2 is represented by a demagnetized section.
· Due to the minute size of these sections, a single disk can hold Terabytes of Data.
· The mechanism of Magnetic Storage devices
Read and Write heads move across the exterior of disk as it is spinning in order to write data, the head magnetizes or demagnetizes a section of the disk spinning underneath as necessary. The head acquires information as to find out whether the section is magnetized or not and data and information is retrieved straight away on to the disk drive with the acquisition of information regarding the location of the data.
The features of magnetic storage devices
· Can be both internal and external
· As tapes are used for permanent storage, reading and writing data can be done using a tape drive and therefore data must be accessed serially
· Slow
· Low cost
· High capacity
· Durable
Optical storage devices
Optical storage devices also referred to as “optical media” or “optical memory” performs read and write tasks using laser beams. Optical storage devices are extremely convenient as due to its compact space and ability to store a huge amount of data. There are many advantages of optical storage devices such as light weight, affordability and portability. DVDs, CDs and blue ray discs are some of the examples of optical storage devices. (Banger, 2021)
The mechanism
They have a laser in order to scan the metal or plastic surface of a spinning disc and the surface of the disc is separated into various tracks.
“When the laser shines on the disc’s surface, lands reflect the light back, whereas pits scatter the laser beam. A sensor looks for the reflected light. Reflected light (lands) represents a binary ‘1’, and no reflection (pits) represents a binary ‘0’.”
Types of optical storage
Read only media (ROM) — The data is read only and cannot be overwritten.
Recordable media (R) — The media is blank and data can be written using a laser beam
Rewritable media (RW) — Similar to recordable media, but can be written more than once. (BBC, 2021)
Flash memory devices
Flash memory is EEPROM which means it is electronically erasable programmable read-only memory and does not need a source of power to hold data. Many portable devices use flash memory to retain data and NAND and NOR are the main types of flash memory. Its non-volatility, durability, maximum portability, storage capacity, faster transfer speeds and compatibility with many devices are some of the main advantages of them and the reason for their popularity. Memory cards, memory sticks and USB flash drives are some examples.
The Mechanism
“Flash memory consists of a grid that has two transistors, the floating gate and the control gate, at each intersection, separated by an oxide layer that insulates the floating gate. When the floating gate is linked to the control gate, the two-transistor cell has a value of 1. To change the value of the cell to 0, a voltage is applied to the control gate that pushes electrons through the oxide layer into the floating gate. Storing the electrons in the floating gate allows the flash memory to retain its data when power is turned off. A voltage is applied to the cell to change the value back to 1. Flash memory is configured such that large sections of a chip, called blocks, or even the entire chip can be erased at a time.” (Gregersen, 2021)
Online cloud storage devices
Cloud storage is a method of transmitting and storing data in remote systems. There are many methods of cloud storage that are now becoming more and more famous due to the fact that many people prefer cloud storage over other storage devices at times.
Cloud storage can be bought from a from a third party cloud vendor who may own storage capacity and operates in it and they ensure capacity, security and durability. (Wesley Chai, 2021)
Here are some of the most common cloud storage services.
Most used storage devices
The most used and common storage devices are decided by the preference of the people and today, this preference is shaped by convenience. The following can be named as the most used storage devices.
· USB flash drive
· Hard disk drive
· SD cards
· Cloud storage devices
· CDs and DVDs
References
Banger, E. R. (2021). Optical Storage Devices: Examples, Types, Advantages, Disadvantages. Retrieved from digitalthinkerhelp.com: https://digitalthinkerhelp.com/what-is-optical-storage-types-devices-examples-advantages-disadvantages/
BBC. (2021). Common types of secondary storage-Eduqas-GCSE. Retrieved from www.bbc.co.uk: https://www.bbc.co.uk/bitesize/guides/zdjqmsg/revision/2
Bitesize. (2021). The need for secondary storage- Memory and Storage. Retrieved from bbc.co.ok: https://www.bbc.co.uk/bitesize/guides/zfssv9q/revision/4
Gregersen, E. (2021). Flash memory | electronics | Britannica. Retrieved from britannica.com: https://www.britannica.com/technology/flash-memory
Hope, C. (2020, 08 02). What is a Primary Storage Device? Retrieved from computerhope.com: https://www.computerhope.com/jargon/p/primstor.htm
hope, c. (2021, 08). What is a storage device? Retrieved from computerhope.com: https://www.computerhope.com/jargon/s/stordevi.htm#needed
Maciej Brodowicz, T. S. (2018). Tertiary Storage- an overview |ScienceDirect Topics. Retrieved from sciencedirect.com: https://www.sciencedirect.com/topics/computer-science/tertiary-storage
Thakur, D. (2021). Different Types of RAM? Explain in Detail- Computer notes. Retrieved from ecomputernotes.com : https://ecomputernotes.com/fundamental/input-output-and-memory/what-are-the-different-types-of-ram-explain-in-detail
Thakur, D. (2021). How can you classify Storage Devices? What are its different types elaborate? Retrieved from ecomputernotes.com: https://ecomputernotes.com/fundamental/input-output-and-memory/how-can-you-classify-storage-devices-what-are-its-different-types-elaborate
Thakur, D. (2021). What is Cache Memory | Types of Cache Memory- Computer Hopes. Retrieved from ecomputernotes.com: https://ecomputernotes.com/fundamental/disk-operating-system/what-is-cache-memory
Wesley Chai. (2021, June). What is cloud storage? cloud storage definition | search gate. Retrieved from searchstorage.techtarget.com: https://searchstorage.techtarget.com/