Computer Storage Devices

Computer Storage Devices.

A storage device is any type of computing hardware, is used for storing, porting, or extracting data files and objects. For any computing device, a storage device is one of the core components that is available in several structures and sizes based on requirements and functionalities. It stores virtually all the data applications except for hardware firmware in a computer. Storage devices can hold and store information both temporarily and permanently. It can be used by a computer system, server, or any comparable computing device to hold information either internally or externally.

The usage of storage devices.

• • • • • • •

The main purpose of the storage devices is to back up or archive our important data.

It can be used to keep data and information in a reliable & permanent way for individuals or organizations.

Secure storage data without physical damage.

It can store as much data as the human brain can remember.

Some kinds of storage devices are used to increase speed and performance in computing devices.

It gives great mobility to the user and the data stored can be easily moved from one place to another.

Acting as hardware to need to run as software and media

.

Storage

Devices

Primary storage

Secondary storage

Tertiary storage

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Offline storage

Primary storage Primary storage is known as main memory, main storage and internal memory is the component of the computer that holds data, programs, and instructions for short periods while a computer is running. Main memory is directly or indirectly connected to the central processing unit (CPU) via a memory bus. Primary storage is located on the motherboard. As a result of this data can be read from and written to primary storage extremely quickly. There are main types of primary storage.

• • •

Read Only Memory (ROM) Random Access Memory (RAM) Cache Memory

The two main types of primary storage are ROM ( non-volatile ) and RAM ( volatile ). Nonvolatile memory keeps its contents even when the computer is switched off. Volatile memory loses its contents when power is lost.

Read Only Memory – ( ROM ) Read-Only memory is the type of electronic storage that can be built into a device during manufacturing. ROM is mostly used for firmware updates. For example, EEPROM, which is a programmable ROM used for the BIOS. Data in the ROM can only be written at once. It is extremely difficult to overwrite data in it. ROM memory can only read data that are written.

There are main three types of ROM. • • •

PROM – Programmable Read Only Memory.

EPROM – Erasable Programmable Read Only Memory.

EEPROM – Electrically Erasable Programmable Read Only Memory.

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Random Access Memory (RAM) RAM is an internal memory that acts as an intermediary between the hard disk and the Central Processing Unit (CPU). The purpose of the RAM is to store data temporarily which are needed by the CPU. RAM is a volatile memory.

There are two types of the RAM • DRAM – Dynamic Random Access Memory • SRAM – Static Random Access Memory

DRAM

SRAM

•

Slower

•

Faster

•

Less Expensive

•

More Expensive

•

Less power Consumption

•

More power Consumption

•

Need to be refreshed thousands of time

•

Does not need to be refreshed .

per second .

Cache Memory Cache memory is used to hold data and programs which ae most frequently used by CPU. It is located inside the CPU. The smaller capacity of the cache memory reduces the time required to locate data within it and provide it to the CPU for processing. It is a very high-speed memory. It’s mainly affected the speed of CPU.

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Secondary Storage Secondary storage is also known as external memory, secondary memory, and auxiliary storage.

Secondary storage devices are used to store data and information permanently needed for the future. It is not directly accessible by the CPU. This is a non-volatile memory.

Today the main storage device is the Hard disk.

Hard Disk (HDD) The hard disk drive is the main, and usually largest, data storage device in a computer. The data in here is read by reading and write header. The speed of a hard disk is measured in rpm (revolution per minute ). Currently, the speed range of hard disks is varying from 4500 to 7200 rpm. Hard disk has different capacity types from 160GB to 8 TB. There are two types of a hard disks as internal & External. (ftms.edu.my, n.d.)

Portability Price Speed Size

Internal Hard Disk No Less expensive Fast Big

External Hard Disk Yes More expensive Slow Small

Tertiary Memory Tertiary storage (tertiary memory) is a level below secondary storage and it involves a robotic mechanism that will mount (insert) and dismount removable mass storage media into a storage device. It’s a comprehensive computer storage system that is usually very slow, so it is usually used to archive data that is not accessed frequently. It’s primarily used to store extraordinarily large data, accessed without human operators.

There are two main types of tertiary storage.

•

Magnetic Tape

•

Optical Disc

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Offline Storage Offline Storage is storage that must be physically connected or inserted into a computer. It is called removable storage. Offline Storage is not under the control processing unit. It must be connected by a human operator. Offline storage is a convenient way to taking our data from one place to another place. These storage mediums are portable and compatible with any computing device. Many organizations used offline storage as backup storage.

Some offline storage devices are used mostly. (ftms.edu.my, n.d.)

• Portable Hard Disk • Magnetic tapes • USB Flash drives • Memory cards • Floppy Disk • Zip diskette

Types of computer Storage Devices Magnetic Storage Devices Magnetic storage media and devices store data in the form of tiny, magnetized dots which are created, read, and erased using magnetic fields created by very tiny electromagnets.

These magnetic dots are arranged in plastic, metal, or glass disc that has a magnetizable coating.

Magnetic storage devices have huge capacities for storing data at a low cost but their accessing power is low. (igcseict, n.d.)

Examples of magnetic storages devices • • • •

Magnetic tape Hard disk Floppy Disk Zip Disc

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Magnetic Tape • • •

•

Magnetic tape is the one of the oldest technologies which use for store electronic data.

There is a magnetically coated plastic strip that can encoded data in magnetic tape.

Due to the high capacity, low cost and long durability, magnetic tapes are well suited for archiving electronic data.

It’s very valuable storage technology but its use has been reduced due lack of random access and speed .

Floppy Disk • • • • •

Floppy Disks were used for transfer small amount of data between computers .

It is a removable, portable, cheap, low-capacity (1.44MB) storage medium .

Access time is too slow .

These devices are obsolete now .

It has two common sizes . They are 5 ¼” and 3 ½”. (ftms.edu.my, n.d.)

Zip Disk

• Zip disk were used for transfer large amount of data between computers.

• It’s removable, portable and relatively cheap .

• Another obsolete device now .

• It’s appearance looks like a standard 1.44 " floppy disk . (ftms.edu.my, n.d.)

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Optical Storage Devices Optical storage devices save data as patterns of dots that can be read and creates using light, laser beam.

Creating dots by using laser beam called burning data on to a disk . The data on the optical storage medium is read by bouncing the laser beam off the surface of the medium. (ftms.edu.my, n.d.)

There are three main types of optical storage devices.

• • •

CD (Compact Disc) DVD (Digital Versatile Disc) BD (Blu-Ray )

Capacity

Wavelength

Speed

CD

DVD Blu-Ray • • •

CD DVD Blu-Ray

ROM - Read Only Memory RW – Rewritable Memory R – Write Once

Flash Storage Devices Flash storage devices is a type of Electronically-Erasable Programable Read-Only Memory . Data in flash memory is stored in an electronic circuit . Flash storage devices are non volatile memory .

These memory devices are the most popular and easy wat to taking data one place to another place . It is very cheap and it has a high speed and high capacity.

Examples – USB Flash Device and Memory Card (SD card) Page 7 of 11

Examples

USB Flash Drives • • • • •

A small, portable flash memory.

It’s plug into a computer’s USB port.

Very easy to read and write data.

High speed.

Available sizes: - 256MB, 512MB , 1GB, 2GB, 4GB, 8GB ,16GB up to 1TB .

Memory Card • •

Memory card is very small flash memory device .

It most use for digital cameras, MP3 players, mobile phones, and other small portable devices.

It reads by connecting to the computer or by using a USB Card Reader

•

: Memory Card Reader

Offline Cloud Storage Devices.

Online Cloud storage is a cloud computing model in data which is organized logically, is stored on remote servers, and accessed over the internet or through a dedicated private network connection. The cloud storage services are maintained, operated, and managed by the cloud storage service providers such as SLT, Microsoft. (ftms.edu.my, n.d.)

There two types of online storage devices.

•

Cloud Storage o It is a cloud computing model that transmits and holds data on remote storage systems where a cloud computing provider gives available data to users over a network.

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Network Media o It’s used on a computer network such as the Internet, as it is any audio, video, images or text. Many organizations use network storage media to share their data in their business network. These are design to be accessible only to authorized persons.

Advantage of cloud storage •

Can access data in anytime, anywhere .

•

High Security

•

Low cost & Durability Page 8 of 11

Disadvantages of cloud storage •

Network failures

•

Need good internet connection

• Access Time

MR

• Cost per Bit

Cash RAM USB Flash Hard Disk

• Frequency of access

by CPU

CD / DVD / Blu-Ray

➢ Hard disk High capacity &Low cost

•

Low speed

(Primary)

Magnetic Tape/ Disc

Most Used Storage Devices •

Volatile Memory

➢ Magnetic Tape • High capacity & Low cost • Lack of accessing durability ➢ Cloud Storage • High capacity & Low cost • High Protection • Can access data anytime, anywhere from any device • Need good internet connection ➢ USB Flash Drive • Portable, Durability & High Speed ➢ SSD , NVMe • High Speed • High Cost Page 9 of 11

Non-volatile Memory (Secondary)

➢ SD Card • Portable & Low Cost ➢ CD / DVD / Blu-Ray • Portable & Low Cost • Low Speed & Low Capacity ( CD )

Characteristic of computer Storage Devices ➢ Volatility • Volatile – It retains its contents while powered, but when power is interrupted stored data is immediately lost.

• Non-volatile – It maintains its content when unpowered. ➢ Accessibility • Random Access – Can access any location in storage device at any moment in approximately the same amount of time.

• Sequential Access – The accessing of pieces of information in storage device will be in a serial order, one after the other. ➢ Differentiation • Dynamic random-access memory – This is volatile memory. It requires the stored information to be periodically re-read and re-written, or refreshed, otherwise it would vanish.

• Static memory – A form of volatile memory. It similar to DRAM with the exception that it never needs to be refreshed as long as power is applied. ➢ Mutability • Read/write storage or mutable storage – Can rewrite data any time.

• Read only storage - Once the manufacturer has entered the data, the data can be entered one more time.

• Slow write, fast read storage – It allows to rewrite data in multiple times, but write operation speed is slower than read operation speed. ➢ Addressability • Location-addressable - Each individually accessible unit of information in storage is selected with according to its numerical addresses.

• File addressable – In here information is divide into two types. They are files of

•

variable length, and a particular file is selected with human -readable directory and file names.

Content-addressable – Information is divided individually according to basis of (part of) the contents stored in them to accessible unit.

(gonagalamahavidyalaya, n.d.)

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References ftms.edu.my. (n.d.). Retrieved from http://www.ftms.edu.my: http://www.ftms.edu.my/images/Document/CSCA0101%20%20Computing%20Basics/csca0101_ch05.pdf gonagalamahavidyalaya. (n.d.). Retrieved from gonagalamahavidyalaya.com: http://gonagalamahavidyalaya.blogspot.com/p/characteristics-of-storage.html igcseict. (n.d.). Retrieved from https://www.igcseict.info: https://www.igcseict.info/theory/3/mag/index.html

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