Snow Leopard has been released! Whoopedoo! But I got no Mac to play with right now. Not counting my Dell Mini 9 of course..
One of reported goodness that comes out from changing the species of OS X is that the harddisk space is finally displayed correctly. You buy a 500GB drive, and “500GB” is displayed, instead of “465GB”. What happens to the missing space in the latter, you ask? This happens to be one of the many questions that keeps surfacing on tech forums.
Let’s take that figure, 500GB, as an example. From manufacturer’s point of view, 500GB, or 500 gigabytes, means 500,000,000,000 bytes. Thus, giga- means multiplied by 1,000,000,000. This is what I like to call “human mode”. We give abbreviations to every three zeroes that we see. 1,000 = kilo; 1,000,000 = mega; 1,000,000,000 = giga. We are creatures who live, breathe and sleep in base-10. I’m guessing this is because that particular base is conveniently equivalent to the numeric system. We use 10 symbols to represent numbers, so we think in base-10.
However, computers think in binary, in base-2. Somehow, we also programmed that into our software as well. So in most OSes, a kilo = 1024; a mega = 1024*1024 = 1048576; a giga = 1024*1024*1024 = 1073741824. Thus, taking 500,000,000,000 divided by a computer’s giga, we get 465 gigabytes.
So which one is correct? Are manufacturers screwing us all this time?
My answer: no.
I guess I prefer standard units as defined by a proper governing body, not marketing. I hate it when people use terms such as “HD-Ready”, “Full-HD” or “SATA2″, because there is no such thing. HD format is usually displayed in 720i, 720p, 1080i or 1080p. Any screen capable of displaying this is HD. There is no specification for SATA2, only SATA-150 or SATA-300. Somehow, people have gotten used to thinking that SATA2 is the latter, which is again fundamentally wrong.
The terms “kilo”, “mega” and “giga” are all standard SI-unit prefixes, along with other prefixes shown in this table:
Because the SI prefixes strictly represent powers of 10, they should not be used to represent powers of 2. Thus, one kilobit, or 1 kbit, is 1000 bit and not 210 bit = 1024 bit. To alleviate this ambiguity, prefixes for binary multiples have been adopted by the International Electrotechnical Commission (IEC) for use in information technology.
Thus, the correct SI prefixes for binary numbers are:
That is why, in this case, the space reported by an OS (except Snow Leopard) is wrong and should use “kibi”, “mebi” and “gibi” instead, to properly distinguish itself from the prefixes for powers of 10.
I’m glad that Snow Leopard is at least attempting to get it right. Of course, on the flip side, people are reporting outrageous space savings when moving from Tiger/Leopard to Snow Leopard. I do know that there are savings, but to report space savings of 20GB is a bit too ridiculous. I’m sure engineers at Apple are freaking smart, but they’re not miracle workers.
Apparently, the SI prefix for binary numbers have been set since 1998. The standard has been set more than 10 years ago! Why are Windows still stuck reporting GB as GiB? Is it so difficult to change that behaviour? Or is Microsoft just scared to change, in case the millions of idiots using Windows start a class-action lawsuit?
I just hate discrepancies.
