HARDCORE COMPUTER SCIENCE

~DILSHAN 10B1~

OFF-LINE STORAGEIt’s any storage medium that must be inserted into a storage drive by a person before it can be accessed by the computer system. Off-line storage may also be written as a removable storage.

Examples:1. CDs2. DVDs3. Flash Drives

CD/DVD DISCCD (Compact Disc)= it’s a small plastic disc on which music or other digital information is stored in the form of a pattern of metal-coated pits from which it can be read using laser light reflected off the disc.

DVD (Digital Versatile Disc)= it’s a disc capable of storing large amounts of data on one disc the size of a standard compact disc.

DVD-RAMDVD-RAM uses a very different technology to CDs and DVDs. They have the following features:

Instead of a single, spiral track, they use a number of concentric tracks.

Use of concentric tracks allows simultaneous read and write operations to take place.

They allow numerous read and write operations (up to 100,000 times) and have great longevity (over 30 years) which makes them ideal for filling files.

BLU-RAY DISCSBlu-ray discs is a digital optical disc data storage format which is capable of storing high-definition video resolution (1080p).

However, they are fundamentally different on DVDs in their construction and in the way they carry out read-write operations. The main differences are:

A blue laser, rather than a red laser, is used to carry out read and write operations.

It automatically comes with a secure encryption system which helps to prevent piracy and copyright infringement.

USB FLASH MEMORIESIt’s a data storage device that includes flash memory with an integrated Universal Serial Bus (USB) interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disk.

They usually connect to a computer through the USB port. Complex or expensive software often uses memory sticks as a dongle.

Examples:1. Flash Drives 3. Floppy Disks2. Memory Cards

REMOVABLE HARD DISK DRIVES (HDD)These are detachable hard drives which can be connected to the computer using one of the USB ports. In this way, they can be used as a back-up storage device.

External drives come with different data transfer speeds. It used to be USB 2.0 but the new units come with USB 3.0 speed, which is faster.

ESTIMATING THE SIZE OF A FILEEstimating the size of a text file is relatively straightforward. Each character from the keyboard has a value of 1 byte.

Suppose we type in the following message:PC is pretty cooland then saved it under the filename `false info’. If we then looked at the properties of the file saved, we will see:

If we count the number of characters in the text types in including the spaces, we get the number 17.

IN CONCLUSION…

THAT’S ALL I HAVE TO SAY TODAY!

~Dilshan 10B1~