How a CDR stores data

3 How a Floppy disk store information 4

3.1 What is a floppy disk made of? 4

Report on how CDs and Floppy disks store information.

In this report I will explain how CDs and floppy disks store information, the differences between them and their uses.

I will start off by talking about how much information a CD can hold then how retail, writable and re-writeable CDs store data, made and are written. Then I will explain how a floppy disk stores information and compare this to how CDs store information.

A standard CD will hold 74 minutes of audio or 650MB of data, but you can get CDs which hold 80 minutes of audio or 700MB of data, there are also 99 minute CDs but these are rare and prone to errors. CDs can come in many physical sizes, a standard CD is 12cm in diameter, but you can also get half size, 8cm disks, as well as square, business card shaped ones, these however only hold about 2MB of information.

The main advantage of CD-R discs is that they work in almost all CD players and CD-ROMS, In addition to this wide compatibility, CD-R’s are inexpensive and easily available. The main drawback of the format is that you can't reuse these discs.

CDs can store more information and are more reliable because the magnetised particles take up lots of space on the surface because they have to be read by a large read/write head, the CD only has to hold small indents which are read by a small laser beam so they can be put closer together, this allows more data to be stored on a CD than a FDD. CDs are more reliable because if you get a finger print, some dust or a scratch on them they can either be wiped off or using special devices the scratches can be removed by shaving a thin layer or the plastic off. But if u scratch a floppy disk or get a finger print on the disk surface they are normally unreadable.

When the data is written on to the disk the computer sends the read head to find a specific address on the disk, the read head then reads the predefined address from the disk to make sure it is on the right surface and place, the erase head will then erase a wider track than is actually written, this stops the written data from being corrupted by other data on the nearby tracks. The write head will follow the erase head writing the data by magnetising the particles on the disk area. The computer can tell what the magnetised particles mean by the way the north and south poles are arranged, the different arrangements will be read as 1’s and 0’s by the computer.

Some topics in this essay:
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