Computer Fundamentals

Computer Fundamentals MSCH 233 Lecture 7

Magnetic Drives Types of Magnetic Drives: • Floppy drive • Hard disk • Removable hard drive • Tape drive • Pocket-sized drive • Microdrive

Floppy drive • Uses a high density floppy disk • The floppy disk can store 1.44 MB of data • It’s called drive A

Hard Disk • Called C drive • Used to keep software and files organized in a convenient way • Can hold several gigabytes of data

Removable Hard Drive • Zip and Jaz drive are the most popular • Can hold 1.5 GB

Tape Drive • Stores data on tape cartridge • Used for backup purposes • A tape hold up to 10 GB of data

Pocket-Sized drive • Ultra portable drives • Used with mobile computers • Hold 40 MB of data • The Peerless system can hold 20 GB, which allow you to store thousands of MP3 and video games.

Microdrive • Smallest hard drive • Used for digital cameras, laptop, and audio players • It comes in 340 MB, 1 GB • Uses a PC card adapter.

How to protect your data? • Protect floppy against high temperatures • Check for virus before opening a file you received from the Web • Keep a back-up of your data • Magnetic field can damage the information stored on disks, Don’t leave them near the telephone • Keep disks away from water and humidity • When handling CDs and DVDs, hold the disk s around the edge. • Add password and security devices to protect confidential information. • Update your anti virus program regularly since new viruses are created everyday.

Floppy Disk in details • They are called Floppy because they consist of flexible plastic material which has a magnetized surface • When you format a floppy: the tracks in the disk is divided into sectors. • When you save a file: the OS moves the read/write heads of the disk drive toward empty sector, and record the data and write an entry for the directory • When you open the file: The OS looks for its entry in the directory , move the read/write head to the correct sector, and read the file into the RAM.

Hard Disk • Work like a floppy but can hold much more data and spin at a higher speed. • The speed at which hard drive find data is called “ access time” • Access time is measured in milliseconds. • Most hard drive have an access time of 8 to 14 ms • Data transfer rate is the average speed required to transmit data from a system to the RAM. Example 10 MG/second • There are external, internal , and removable hard drives.

Optical Drives Vs. Magnetic Drives • OD can store information at much higher densities than magnetic disks. • OD are Ideal for multimedia applications , where images, sounds and animation occupy a lot of disk space. • OD are not affected by magnetic field • OD are secure and stable • OD are slower than hard drives

Types of Optical Drives: • CD-ROM • CD-RW & CD-R • DVD • Magneto Optical (MO)

CD-ROM • Most economical way of sharing information • Can store 650 MB of data , that replaces 300,000 pages of text ( about 500 floppies) • Can play music, and store data • Cannot write anything onto a CR-ROM . You can only read.

CD-Recorders - Allows you to create and duplicate CDs. • Used to backup hard disk • Used to distribute & archive information Come in two forms: • CD-R (write once) • Can write once only • CD-RW (rewritable) • Can be erased and re-used,

DVD (Digital versatile Disk) • Can hold 17 GB about 25 times an ordinary CR-ROM • Can Store large amount of multimedia software, movies ,and music. • They are read only devices • Companies produced also DVD-R and DVD-RW

Magneto-Optical drives • Use both laser and electromagnet to record information • MO disks are rewritable • Comes in two formats: • 5.25” cartridge and can hold 5.2 GB • 3.5” floptical disks , have capacity of 230 MB to 1..3 GB • Ideal for backup and portable mass storage

Computer Fundamentals