kibi-

[Etymology: kilo- binary] informatics. Symbol Ki-. The 1 024 = 2¹⁰ multiplier, as KiB = kibibytes and Kib = kibibits. This arises as a matter of convenient terminology for memories and similar entities organized on a binary basis. (But see below re communication channels.)

Concerned at the widespread use of SI decimal prefixes for nearby but distinct binary multipliers, the International Electrotechnical Committee in 1999 adopted as an international standard (outside of the SI) a range of revised multiplier prefixes, derived from those of the SI, implying the true binary values. Specifically and uniformly, the familiar decimal multiplier prefixes were modified by the appendage of the letters ‘bi’ to the initial two letters of the SI prefix (the appendage being pronounced ‘bee’, the beginning as with the SI). The symbols are similarly those of the SI with an appendage, namely the single letter i, except that, for consistency within the new set, the capital K was retained. These prefixes are shown in Table 31. It should be realized that many memories and other devices have only nominally the stated size if interpreted as precisely the binary power. Further, with the ‘56k’ modem the symbol k is neither the decimal 1 000 nor the binary 1 024. The nominal speed is 57 600 bps, making k = 1 028.6~ so close to the binary kibi-. (The figure derives from multiplying 300, the first baud rate above telegraph speed. This rose binarily to 4 800 before eight-layer signalling made a tripling to 14 400 bps. Successive doubling of this figure brought the 57 600.)