Storage devices are the devices where we electronically store/record data in the computer. Storage devices can be removable or non-removable depend on their type. Most commonly used storage devices are non-removable can be found inside of CPU casing. Storage devices can be classified into 3 three different categories Primary, Secondary and Tertiary storage devices. These devices are non-volatile storage devices means they don't lose data when powered off. Before we move on you may already know that computer does any kind of data transferring in form of bits (0,1). Some of the common storage devices are:
1. Floppy Disk Drive
Floppy disk drive is basically an input/output device. It was one of the most popular storage device of the past and still it is for some people. However, today USB flash drives replacing it as one of the better alternative of floppy disk drives. Floppy disk is basically a circular shaped flexible plastic which closed inside a solid plastic cover layered with soft foam on both sides.
One of the main reason of floppy disk’s popularity is the cheap price and capability of data read/write. The data stored in floppy disk is portable and you can transport it to any other computer that has floppy disk drive installed already. Floppy disks are getting rare now, because of high data corruption rate, slow data transfer (read/write), and very small data storage capacity of only up to 1.44 Megabytes which is one of the biggest disadvantage of it. Anyways, It could still be a good option to make the backup of your small documents like a Microsoft Word document or some low-resolution images, etc..
You may wonder that some businesses and industries still regularly use floppy disk drives. Personally I had seen someone installing Windows 3.x using four floppy disks for embroidery machines.
2. Hard Disks or HDD:
A Hard disk consists of one or more circular disks of aluminum or other metal alloy coated with magnetic material on both sides. It’s a mass storage device capable to store large amount of data for long time-period with higher data transfer rate (read / write data). That’s why an HDD is the most common part of any system. A hard disk is commonly a Fixed disk since they can be found inside of a CPU casing, but lacks in capability of moving data from one to another place.
Note: We use portable hard drives (or External HDD) which allows to move large amount of data anywhere stored inside of an external HDD.
One of the greatest speed factor of hard disk is instead of reading the stored data inside a hard disk from the beginning it directly reaches to the exact location where data is actually stored (i.e direct access device). A hard disk can be used to store OS files, applications, files and folders etc. We'll discuss about hard disk speed factors to help you to buying good quality hard drives.
3. Optical Storage Media:
i) CD ROM (CD-R and CD-RW)
CD ROM is an abbreviation of Compact Disk Read Only Memory also a common storage device. As we said above hard disk drives read/writes data at much faster rate than a floppy disk, then why we still need a CD ROM, and the simple answer is a CD can store up to 700 MB of data in it and allows to move CD data from one place to another with ease and portability. On the other hand, floppy disk can store up to 1.44 MB which is not just enough today. It's also very cheap to buy a CD and software development companies are selling their softwares in CDs. You can get a complete version of of their softwares within single CD.
Let's give you an example, in past when CDs were not available Microsoft Office had supplied with 32 floppy disks, But thanks to the invention of optical storage media and CD ROMs now this software is available in one CD or DVD for latest versions. You can install softwares from CDs more quickly than a floppy disk drive due to better data transfer rate of CD ROMs.
CD-R: Used for read-only data, allows one-time data recording on the disk. It’s an abbreviation of Compact Disk Recordable.
CD-RW or CD Burner: Used for reading / writing / erasing of data to a CD more than once. CD-RW is an abbreviation of Compact Disk Re-writable. You need a classified CD-RW disk not just a CD-R disk for recording/erasing data multiple times. Remember that, a CD-R disk can only be used to record data once. Many people forget this when when buying compact disks for the same purpose.
ii) DVD ROM (DVD-R and DVD-RW)
A DVD drive can store much more data than a CD can. An average DVD can store up to 4 GB of data however the latest dual-layered DVDs are capable to store up to 8 GB of data. The main purpose of DVD drives to store movies, games or any other stuff beyond the capacity of a CD. You need a DVD ROM to to read these disks. Like CDs DVD drives also come in two types: DVD-R, DVD-RW / DVD Burner; one for just reading the disk and other for data reading and writing both.
4. Flash Memory / Pen Drives:
A USB Flash drive is a portable or removable data storage device that allows you to move data anywhere and give immediate access to the data (because of plug and play support). They’re compact in size not bigger than a human finger can easily slide into your pockets and capable to store data anywhere from 256 MB to 512 GB.
It’s a better way to transport your data whenever you want and wherever you want . These devices are considered as backup devices and are also known as thumb drive / pen drive / Keychain drive and solid state drive (SSD the technology used in camera and smart phones and other devices – unlike HDD it stores data in integrated circuits & chips without movements of parts). USB flash drives are cheaper than a floppy disk as compare to data storage space they offer.
5. Magnetic Tapes / Tape Drives
Tape drives have been using for decades regarded as the most popularly used storage device ever. These devices store data using tape or cartridge coated with magnetic material provide low-cost data storage than any other disk drive can offer. These storage devices specifically used as a backup data storage. Magnetic tapes are very slow at data transfer due to sequential read/write mechanism.
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