ICT in Business - 0611 - 113 Lecture 2 Storage Device What is a Storage Device? A storage device is an integral part of the computer hardware which stores information/data to process the result of any computational work Without a storage device, a computer would not be able to run or even boot up Or in other words, we can say that a storage device is hardware that is used for storing, porting, or extracting data files Example: Flash Drive: A modern - day staple and you should have seen one of these before. These are also commonly called the “pen drive” or “thumb drive”, depending on where you are in the world. The purpose of a storage device Major purpose of storage devices is to hold data - even when the computer is turned off - so the data can be used whenever it is needed. Storage involves two processes: • Writing, or recording, the data so it can be found later for use. • Reading the stored data, then transferring it into the computer's memory Types of Storage Device Storage Device Primary Storage Secondary Storage Tertiary Storage Primary Storage Device It is also known as internal memory and main memory. This is a section of the CPU that holds program instructions, input data, and intermediate results. It is generally smaller in size. Two primary storage devices are: 1.Ram(Random Access Memory) 2.ROM(Read Only Memory) RAM(Random Access Memory) RAM (Random Access Memory ): It is used to store information that is used immediately or we can say that it is a temporary memory. With the help of RAM, computers can perform multiple tasks like loading applications, browsing the web, editing a spreadsheets, experiencing the newest game, etc. It allows you to modify quickly among these tasks, remembering where you’re in one task once you switch to a different task. Three classifications of RAM are given below: • SRAM (Static Random Access) • DRAM (Dynamic Random Access Memory) • SDRAM (Synchronous Dynamic Random Access Memory) ROM (Read Only Memory) It is typically used to store firmware or microcode, which is used to initialize and control hardware components of the computer. It is also used in other electronic items like washers and microwaves. ROM chips can only store a few megabytes (MB) of data, which ranges between 4 and 8 MB per ROM chip. Classifications are given below: PROM (Programmable Read Only Memory) EPROM (Erasable Programmable Read Only Memory) EEPROM (Electronically Erasable Programmable Read Only Memory) Mask ROM. Magnetic Storage Device Magnetic storage uses different patterns of magnetisation in a magnetizable material to store data and is a form of non - volatile memory. The information is accessed using one or more read/write heads . Magnetic storage media, primarily hard disks, are widely used to store computer data as well as audio and video signals. Magnetic storage device Floppy Disk: Floppy Disk is also known as a floppy diskette. It is generally used on a personal computer to store data externally. A Floppy disk is made up of a plastic cartridge and secured with a protective case. Nowadays floppy disk is replaced by new and effective storage devices like USB, etc. Hard Disk: Hard Disk is a storage device (HDD) that stores and retrieves data using magnetic storage. It is a non - volatile storage device that can be modified or deleted n number of times without any problem. Most computers and laptops have HDDs as their secondary storage device. The read - write speed of HDDs is not so fast but decent. It ranges from a few GBs to a few and more TB • Magnetic Card : It is a card in which data is stored by modifying or rearranging the magnetism of tiny iron - based magnetic particles present on the band of the card. It is also known as a swipe card. It is used like a passcode (to enter th e house or hotel room), credit card, identity card, etc. Tape Cassette: It is also known as a music cassette. It is a rectangular flat container in which the data is stored in an analog magnetic tape. It is generally used to store audio recordings. • Super Disk: It is also called LS - 240 and LS - 120. It is introduced by Imation Corporation and it is popular with OEM computers. It can store data up to 240 MB. Formula: Storage capacity of a disk= Total number of surfaces x Number of tracks per surface x x Number of bytes per track. Problem : Consider a disk pack with the following specifications - 16 surfaces, 128 sectors per surface, 256 tracks per surface and 512 bytes per track. What is the capacity of disk pack? Solution : Given, • Number of surfaces = 16 • Number of tracks per surface = 128 • Number of sectors per surface = 256 • Number of bytes per track = 512 bytes We Know, Capacity of disk pack = Total number of surfaces x Number of tracks per surface x Number sectors per surface x Number of bytes per track = 16 x 128 x 512 bytes = 1048576 Bytes = 1048576 /( 1024*1024) MB = 1 MB Therefore, Capacity of the disk pack is 1 MB. Storage capacity calculation of a magnetic storage device Storage capacity of a disk= Total number of surfaces x N umber of sectors per surface X Number of tracks per sector x Number of bytes per track. Problem : Consider a disk pack with the following specifications - 16 surfaces, 12 sectors per surface, 126 tracks per sector and 512 bytes per track. What is the capacity of disk pack? Solution : Given, • Number of surfaces = 16 • Number of sectors per surface = 12 • Number of tracks per sector = 126 • Number of bytes per track = 512 bytes We Know, Capacity of disk pack = Total number of surfaces x Number of tracks per surface x Number tracks per sector x Number of bytes per track = bytes = 1048576 Bytes =1048576 /(1024*1024) MB = 1 MB Therefore, Capacity of the disk pack is 1 MB Optical Storage Device Optical Storage Devices is also secondary storage device. It is a removable storage device. Optical storage is any storage type in which data is written and read with a laser. Major two types of optical storage device are: 1. CD: It is known as Compact Disc. It contains tracks and sectors on its surface to store data. It is made up of polycarbonate plastic and is circular in shape • CD - R • CD - RW 2. DVD: It is known as Digital Versatile Disc. DVDs are circular flat optical discs used to store data. It comes in two different sizes one is 4.7GB single layer discs and another one is 8.5GB double - layer discs • DVD - R • DVD - RW An Optical Disk Drive Solid State Storage Device (SSD) Non - volatile computer storage that stores and retrieves digital information using only electronic circuits, without any involvement of moving mechanical parts. SSS devices typically use flash memory , but some use battery - backed random - access memory (RAM ). Devices come in various types, form factors, storage sizes, and interfacing options to satisfy application requirements for many computer systems and appliances. Optimizing Disk Performance Optimizing disk performance refers to the process of improving how efficiently a computer's storage drives (such as hard drives or solid - state drives) read and write data Optimize is important for : Speed and Efficiency Longevity of Hardware Data Management The way we can optimize Defragmenting a disk Scanning a disk for error Cleaning up unneeded files