Friday, 23 July, 2004

If you've used the metric system then you'll have seen magnitude prefixes. You know, Kilo == 10³, Mega ==( 10³)²==10⁶, Giga == (10³)³==10⁹, Terra==(10³)⁴==10¹² and so on and so forth.

These magnitude prefixes are defined under the SI (Systeme International d'Unites) and every physicist, chemist, electrician or just about anybody in Europe understands these prefixes.

However, if you're working with a computer then this system of prefixes changes. A Kilobyte becomes not 10³ bytes but 2¹⁰. A megabyte is 2²⁰ bytes, a terrabyte is 2³⁰ and so on.

I don't really see a problem with this change of definition after all computers prefer base-2 but some one obviously did. In December 1998 a proposal was ratified by the IEC with the aim of cleaning the apparent 'confusion' up. A collection of base-2 prefixes was established, the kibi (pronouced ke-bee), mebi (me-bee), gibi (gi-bee), tebi (te-bee) etc. For a little article describing why this was done see here.

Simon.