Today the biggest hard drive out there is in the order of 1.5 “Terabytes.” Why do I say “Terabytes” rather than just Terabytes? Well to answer this we need to know how we go from a Bit (a single 1 or 0) to a Terabyte (Trillions of bits). Also we will explore why when you purchase a hard drive that says 80GB or 750GB why it only comes with about 74GB and 730GB respectively.
Adding It All Up–
The smallest unit of measure in the computer world, nay every world, is a Bit. A Bit is a 1 or a 0. It can not be a 2 or a -1 it can only be either 1 or 0. On or off, high or low, how ever you put it, this is fundamental. The reason being, when you take 8 Bits and group them together, we have what is know as a Byte. A Byte holds enough information to represent a single character. So lets recap, 8 Bits = 1 Byte.
Now from here on out we count using power of 2 e.g. 2^n. The next important number however is 1024. This is because to go from Bytes to Kilobytes, it takes 1024 Kilobytes. Now we have 8192 Bits = 1024 Bytes = 1 Kilobyte.
Now since this is going to get very long, lets take a look at the shorthand notation of each of these. Bit is equal to lower case “b.” Byte is equal to upper case “B.” Kilo is typically “K.” So if we want to say 56 Kilobits we can say 56Kb. However if we wanted to say 16 Kilobytes we would say 16KB. Typically you do not just use “b” or “B” by themselves, instead write out the whole word Bit and Byte respectively.
So from here on out we have all the needed information to reach the rest of the numbers. The next unit up from KB is MB or Megabytes for millions of Bytes. There are 8,388,608 Bits, 1,048,576 Bytes, or 1024 KB in 1 MB. This will continue up the food change with the next ones being Gigabytes (GB), Terabytes (TB), and in the not too distant future, Petabytes (PB)! This brings me back to that issues of the ” “.
1000 vs. 1024–
If you read the back, bottom, and sometimes even the front of the box carefully (or if its an OEM drive go the manufactures website), you will notice something along the lines of 1KB is equal to 1000 bytes not 1024 bytes because they are using the metric way of counting rather than the binary way computers do.
I know what your thinking, it’s only a few bytes right? Well yes but that’s for each KB. It gets worse when we go from up the ladder.
The Real Issue–
It all comes down to marketing. These drives are marketd as 1TB are really about 99GB less than that. If these drives were marketed as 901GB or 900GB hard drive then it wouldnt be an issue. It comes down to two things really, you can sell “more” harddrive space for less, and because 1TB just sounds more sexy!
If your attentive you may have noticed another advertising “gotcha” when it comes to broad band speed. If we look at Comcast for an example, they offer 6Mb/s. Thats 6 Megabits not Megabytes per second. That means if you take whatever number they give you(6Mb/s), convert it to bits (6,291,456)
, divide by 8 (786,432), then represent that in either KB/s or MB/s (786 KB/s). This number is your actual maximum download speed as your computer would measure it.