1. Introduction to computer storage

2. Computers only understand electrical signals
A electrical signal can either be on or off, like a light switch.
The computer reads this as either 1 or 0
1 is on and 0 is off

3. In fact computers are just a collection of electrical components

4. So how do we store data on computers?
Using a memory stick
Loading a file from the hard drive
Inserting a CD-ROM or DVD

5. All done with 0 and 1 magnetic storage
On a computer hard drive data is stored using magnetism
A magnet has two poles North or South
North represents 1
South represents 0

6. All done with 0 and 1
The magnetic surface of the hard drive records thousands of 0 and 1’s which make up the data.
Magnetic surface
Computer hard drive

7. Magnetic storage

8. Optical storage
CD-ROM’s or DVD’s are called optical drives they use light to represent data.
The disc surface is reflective, data is written on the disc by a laser which burns holes through the reflective surface.
A light beam is reflected from the shiny surface but not reflected if there is a hole.
Reflected light represents 1
Non reflected light represents 0

10. video Video

11. Flash memory
Flash memory stores data electronically it uses tiny electrical components called transistors to store the data. Each memory location has a transistor which can store either a 1 or 0. Flash memory retains its information when the power is switched off this is called non volatile. Examples of flash memory are:-

12. Flash memory USB Memory sticks SD cards for Phones and cameras
Solid state hard drives SSD
Mobile phone Sim card

13. Technical details
Flash memory is transistor-based and non-volatile. Flash , therefore, has no moving parts and information stored on the NAND flash memory chip remains until you delete/edit the file.
NAND flash gets its name from the NAND gate in Boolean logic.

14. Technical details
The flash memory cell acts like a permanently-open or closed transistor. Charging is accomplished by grounding the source and drain terminals and placing a voltage on the control gate. When the “floating gate” is charged, it impedes the flow of electrons from the control gate to the silicon, and the 0 or 1 is determined by whether the voltage on the control gate is blocked or not.

15. Your task
To create a PowerPoint presentation which explains the three different storage method’s
Show examples of each
Explain how they work
Include the following information
Capacity(how much can it store)
Speed how fast is it
and how much does it cost?
Use the website below to find information

16. Further research
SSD or solid state hard drives are now replacing traditional magnetic hard drives why is this? Find out why and explain.
Magnetic storage was developed early on in the history of computing and is still the main method of storing data on computer system. So why were optical and solid state technologies developed?