Introduction to computer storage

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 0011010101001111001110001101011110010

In fact computers are just a collection of electrical components

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

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

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. 01010001000010000011111000001111110001 Magnetic surface Computer hard drive

Magnetic storage

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

video Video

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:-

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

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.

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.

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 http://www.igcseict.info/theory/3/index.html

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?