A GigaByte does not necessarily equal a GigaByte
Here's another situation where you can look really smart if you paid attention and know the difference between the binary and the decimal system. This question is asked over and over again:
"I bought a 8.4GB hard drive, but when I formatted it, Windows tells me that I have only 7.82 GB available. Did they sell me the wrong drive?"
No, they sold you the correct drive, but it was not labeled quite correctly. The marketing department of the drive manufacturer doesn't know too much about bits and bytes and the binary system. To make it easier to calculate, they assume that 1 KB is 1000 Bytes, 1 MB is 1000 KB, etc. which is wrong. So when they have a drive that can hold 8,400,000,000 Bytes, they just call it 8.4 GB and say that's close enough for government work. Not so.The multiplication factor is not 1000 since we're not using the decimal system, it is 1024 instead (2 to the power of 10).
To figure out the correct size of that drive, divide 8,400,000,000 Bytes by 1024 and you'll get 8,203,125 KB. Divide that by 1024, and you get 8,010 MB. Divide that by 1024 and you get 7.82 GB which is the actual size of your hard drive in GB as reported by your operating system.
Of Pits and Grooves
A CD stores data using the binary system in the following matter: When writing data to a CD, the laser does nothing else than following a spiral-shaped "guide groove" while burning the data as a long string of pits into a reflective dye layer on the CD. When the CD is read later, a laser follows the same spiral and reads either a pit where the light does not get reflected very well, or a smooth area called land where the light reflects very well. This system is nothing else but our good old binary system, using only two possible states, pit or land, to read and record data in binary format, 0 or 1.
Storing data on a magnetic media, such as a hard drive, also uses the binary system. In a very simplified manner of speaking, each data bit gets stored on a drive as a tiny magnetic field. Each magnetic field has two poles, North and South. When the disk spins around and data is read by the read head, the magnetic field either has the North or the South pole aligned first. Again, only two possible stages, North or South, 0 or
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