On kibibytes, mebibytes, Kibbles 'n Bits

Christopher Bazley, January 2010

In 1998, the International Electrotechnical Commission invented the prefixes 'kibi', 'mebi' and 'gibi' to replace the well-established prefixes 'kilo', 'mega' and 'giga' when referring to 210 (1,024) bytes, 220 (1,048,576) bytes and 230 (1,073,741,824) bytes. For example, 230 bytes would be "one gibibyte" according to the IEC. In my opinion these neologisms are ugly and unnecessary.

In the context of SI units (the metric system), the prefixes 'kilo', 'mega' and 'giga' mean multiples of 103 (1000), 106 (1,000,000) and 109 (1,000,000,000) of the base unit. SI units are the standard in science. However, computing is not science; it is engineering. As far as I know, 'megas' and 'gigas' simply mean 'large' and 'giant' in Greek.

In my opinion, any conclusions drawn from the fact that computing happens to use the same set of prefixes as the metric system are specious. If the world is big enough to accommodate both nautical miles and statute miles then I don't see why computing shouldn't be allowed to use units of measurement suited to a binary rather than decimal system, and not have new names for those units imposed by diktat.

To appease metric pedants, computers with a 16 bit address bus (allowing up to 216 bytes or 64K of contiguous memory) would instead have had to be designed with a 15.96578429 bit address bus! That might have presented some engineering challenges, but it would at least have ensured a nice round decimal figure of 64,000 rather than 65,536 bytes of memory.

Alternatively, such machines could have been marketed with memory described in units of 1,000 bytes, which would have confused the hell out of consumers. (Trying searching on eBay for a "Boxed 49.152K ZX Spectrum in mint condition" - I guarantee you won't find one.)

 I can just imagine the playground arguments:

"My computer's better than yours."
"Is not."
"Is too! My computer has thirty-two point seven six eight kilobytes."
"Aw crap, my computer only has sixteen point three eight four kilobytes."

Yeah, right!

Incidentally "Kibbles 'n Bits" is a brand of dog food, which coincidentally reflects my feelings about "kibibytes".