IT Essentials - Lec 4-1 PDF

Section 3 Storage Lesson 11 Storage Devices  Lesson 11 – Storage Devices Storage in Computer In Computer, we can save Data/Information in many forms and devices. All computers work on a binary numbering system, i.e. they process data in one's or zero's. This 1 or 0 level of storage is called a...

Section 3 Storage Lesson 11 Storage Devices  Lesson 11 – Storage Devices Storage in Computer In Computer, we can save Data/Information in many forms and devices. All computers work on a binary numbering system, i.e. they process data in one's or zero's. This 1 or 0 level of storage is called a Bit. The smallest unit of computer memory is Bit. It can store either 1 or 0. Measurements of computer storage/memory are: 8 Bits 1 Byte 1024 Bytes 1 Kilobyte (Kb) 1024 Kilobytes 1 Megabyte (MB) 1024 Megabytes 1 Gigabyte (GB) 1024 Gigabytes 1 Terabyte (TB) Lesson 11 – Storage Devices Storage Devices Some storage devices are as follows: ◼ Hard disk ◼ Floppy disk ◼ Compact disk (CD) ◼ Digital Versatile Disk (DVD) ◼ Memory Stick/Flash Memory Lesson 11 – Storage Devices Hard Disk Generally, Data and computer programs are stored in the hard disk. There are two types of hard disk. ◼ Internal Hard Disk ◼ External Hard Disk Lesson 11 – Storage Devices ◼ Internal Hard Disks  These are inside the system unit/Box.  Their speed is very fast.  They can store huge amount of data often in Gigabytes. A Gigabyte is equivalent to 1024 Megabytes.  Their costs are falling rapidly and normally these are the cheapest way of storing data. Lesson 11 – Storage Devices External Hard Disks ◼ These hard disks are outside the system box and we can connect them to computer using a USB port. ◼ These hard disk normally slower that internal hard disks ◼ These are more expensive than internal hard disks. ◼ Their performance is approximately same as internal hard disks. ◼ They can also store huge amount of data. Lesson 11 – Storage Devices Diskettes (Floppy Disks) ◼ Speed of Floppy disk is very slow. ◼ They can store small amount of data, normally 1.44 Mbytes. ◼ They are very cheap. ◼ They are not reliable. Lesson 11 – Storage Devices CD-ROM Disks ◼ CD-ROM is slower than hard disk but faster than floppy disk. ◼ They can store data around 650 Mbytes. ◼ CDs are also cheap as compared to hard disk. DVD Drives ◼ These are faster than CDs but slower than Hard disk. ◼ They can store data up to 17 Gbytes. ◼ They are a little bit expensive than CDs. Lesson 11 – Storage Devices Memory Sticks/Flash Memory ◼ We can plug them directly into the computer using a USB port and use them. ◼ They are small in size. ◼ They can store good amount of data. ◼ Digital cameras and other new devices have memory cards to store images/data. Lesson 11 – Storage Devices Online file storage ◼ Many websites provide the facility to save data on the internet. ◼ We can store and access data using a PC and internet. ◼ This facility is becoming popular now a days. Lesson 12 Storage Areas Lesson 12 – Storage Areas Storage Areas ◼ In Computer, storage areas are the places where we can store our data. ◼ Computer hard disk can be divided into many parts/sections. ◼ Each section is represented by an alphabet/character, e.g. (E:) ◼ We can also use Network drive which is available to all PCs in a network. Lesson 13 Types of Memory Lesson 13 – Types of Memory Memory In computer, all data and information to do a job/task is stored in memory. Types of Memory There are two types of computer memory. ◼ Random Access Memory (RAM) ◼ Read Only Memory (ROM) Lesson 13 – Types of Memory Random Access Memory (RAM) ◼ This is the main 'working' memory used by the computer. ◼ This is used to store data or program on temporary basis. ◼ When we use any data or program then its loaded into RAM. ◼ When you first switch on the computer, the operating system is copied from disk into RAM. ◼ This is also called Volatile Memory because when we switch off the computer, all data is lost. ◼ Generally, a computer will operate faster if computer has more RAM. Lesson 13 – Types of Memory ROM – Read Only Memory ◼ It is a special type of memory chip that holds software or important information that a computer needs. ◼ Information in ROM can only be read but not written to. ◼ ROM retains information even after the powered is switched off. ROM is non-volatile. ◼ An example is the ROM-BIOS chip, which contains read-only software. ◼ Network cards and video cards also contain ROM chips. Lesson 14 Measuring Memory  Lesson 14 – Measuring Memory Storage in Computer ◼ The smallest unit of computer storage/memory is Bit. ◼ Bit can store either 1 or 0. Measurements of computer storage/memory are: 8 Bits 1 Byte 1024 Bytes 1 Kilobyte (Kb) 1024 Kilobyte 1 Megabyte (MB) 1024 Megabyte 1 Gigabyte (GB) 1024 Gigabyte 1 Terabyte (TB) Lesson 15 Computer Performance Lesson 15 – Computer Performance Factors that Impact on a Computer's Performance We can know and judge the computer’s performance by following factors: ◼ CPU speed ◼ RAM size ◼ Hard disk speed and capacity ◼ The number of applications running