Compare the types of secondary storage media
with respect to portability, speed and capacity
Storage Media | Portability | Speed | Capacity |
Magnetic Tape
|
The tape itself is thin or narrow and is portable. However, the tape needs to be inserted in a tape drive for the data to be read |
Slowest of all storage media, so ideal for backing up old data (archiving) |
Can store up to about 5 Terabytes |
Floppy Disk Were popular in the 1980's and early 2000's
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The disk itself is small enought to be portable. However, the disk needs to be inserted in a disk drive for the data to be read Floppy disks sizes were 5.5-inches, and 8-inches, but the popular size was 3.5-inches. |
Very slow to access and store data |
Between 640kb and 1.44 Mb |
Hard Disk A Hard Disk is normally mounted inside a case. Usually there are multiple hard disks stored in a hard disk drive.
|
Hard disks that are used internally in a computer system are not portable. However, there are now some external hard drives
|
Very fast compared to the floppy and magnetic disk |
Range from hundreds of megabytes to hundreds of gigabytes or terabytes |
Optical Disks Flat, circular, plastic or glass disk on which data is stored in the form of light and dark pits.
Types: Compact DIsk (CD): CD-ROM: CD-Read Only Memory - data cannot be erased from it CD-RW: CD-Rewritable, these disks can be erased and rewritten at any time. Digital Versatile Disk (DVD): DVD-ROM:DVD-Read Only Memory - data cannot be erased from it DVD-RW: DVD-Rewritable, these disks can be erased and rewritten at any time.
|
Portable |
Faster than magnetic tape, but slower than hard disk or flash memory
CD: Can transfer data up to the speed of 7800 KB/s, or about 70 minutes of audio.
DVD: access rates of 600 KBps to 1.3 MBps
|
CD: About 650 MB
DVD:Ranges from 4.7 GB to 17 GB |
Flash Drive small external storage device, typically the size of a finger; inexpensive and durable
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Portable | 30 to 100′s of MB (megabytes per second) | 8 Megabytes to 512 Gigabytes |
Flash Memory Card An EEPROM non-volatile computer storage chip. They are flat and also have a smaller version which is used within cell phones
|
Portable |
About 15 MB/s |
1 Gigabytes -16 Gigabytes |
Let's put access speed for some devices in order:
Pics of storage devices
Flash memory |
Optical storage |
Magnetic storage |
Download summary notes
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