Discovering Computers

Chapter 8: Digital storage

Capacity

8 bits = 1 byte = 1 character (up to 256 different characters including numbers, uppercase and lowercase letters, punctuation and some symbols). See example of a coding scheme, of how 8 bits forms a character.

Timeline: 50 Years of Hard Drives

A comprehensive timeline, beginning in 1956, that details the history of hard drives.

DNA Storage

Data, information, and instructions can be stored in DNA. DNA is a very dense storage source, almost a Zettabyte can be stored in just one gram! The disadvantage of DNA storage is that it is slow and costly. The reading and writing of DNA is improving every year. See videos to learn more, including how 1s and 0s are converted to DNA code and back to data the way it is represented for computers:

External hard disk

I keep all of my data on external hard disks. Here's an example of a hard disk you can purchase on Amazon. Notice it is USB 3.0, which is 10 times faster than USB 2.0 to transfer your data. Refer back to chapter 3 to learn more.

Can you restore deleted files?

Once the recycle bin is emptied, recovery of files are much less likely. Some files are not actually deleted, but instead the file name is just deleted from the directory. There is nothing that refers to the file, so you no longer see it. If you continue to use your computer and wait to recover a deleted file, the less likely you will be able to get it back. Overall, recovery rates of deleted files are low.

It may be possible to recover files from a physically damaged sector on a hard disk. Windows has a Check Disk utility that may help. Use File Explorer in Windows 8.1 (or Windows Explorer in Windows 7), right-click the hard drive and choose Properties from the shortcut menu. Click the Tools tab and Check Now. The utility can't repair the bad spot, but it will try to move the data from the bad sector to a good sector.

SSD vs HDD?

Is your storage media harmed when passed through security screening at airports?

Airport scanners do not damage memory cards, discs (optical), or disks (magnetic media).   Scanners can damage undeveloped film. BTW, there is a new security measure that was put in place in 2014. If you are traveling overseas, be sure your mobile devices are fully charged before returning to the US. Tables, smartphones, and laptops that do not turn on, may be confiscated. Learn more from the TSA and Information Week.

Is a warrant needed to search your smartphone?

Your phone stores your photos, email, text messages and much more. It may have more information about you than at your home. Watch video to learn what the Supreme Court recently ruled on this question.

Cloud storage

The "cloud" consists of servers that provide storage, services, and access to resources. I personally prefer Google Drive as it provides 15GB of storage for free. Why bother with a flash drive?! Below are links to resources, in addition to page 116 of your book, that may be of interest to you.

Optical discs

Enterprise storage: RAID

Companies and organizations may use RAID for storage. RAID is a hard disk system that connects several smaller disks into a single larger unit that acts like a single hard disk.

  • "Mirroring" is the duplication of data on multiple disks. If one drive fails, that data is accessible on another drive.
  • "Striping" splits data among multiple disks, which improves access time, but there is no data duplication.

See a short video that summarizes RAID mirroring and striping.