Kilobyte
Encyclopedia
The kilobyte is a multiple of the unit byte
for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 (210) bytes or 1000 (103) bytes, dependent upon context, in the fields of computer science
and information technology
.
For example, the HP 21MX
real-time computer (1974) denoted 196,608 (which is 192×1024) as "196K",
while the HP 3000
business computer (1973) denoted 131,072 (which is 128×1024) as "128K".
The Shugart
SA-400 5¼-inch floppy drive (1977) held 109,375 bytes unformatted, and was advertised as "110 Kbyte", using the 1000 convention. Likewise, the DEC RX01 (1975) held 256,256 bytes formatted, and was advertised as "256k". On the other hand, the Tandon 5¼-inch DD floppy format (1978) held 368,640 bytes, but was advertised as "360 KB", following the 1024 convention.
On modern systems, Mac OS X Snow Leopard represents a 65,536 byte file as "66 KB", while Microsoft Windows 7 would represent this as "64 KB".
In December 1998, the IEC
attempted to address these dual definitions of the conventional prefixes by proposing unique binary prefixes and prefix symbols to denote multiples of 1024, such as “kibibyte
(KiB)”, which exclusively denotes 210 or 1024 bytes. If the proposal had been widely and consistently adopted, it would have liberated the standard unit prefixes to unambiguously refer only to their strict decimal definitions wherein kilobyte would be understood to represent only 1000 bytes. However, in the over that have since elapsed, the proposal has seen little adoption by the computer industry.
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 (210) bytes or 1000 (103) bytes, dependent upon context, in the fields of computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
and information technology
Information technology
Information technology is the acquisition, processing, storage and dissemination of vocal, pictorial, textual and numerical information by a microelectronics-based combination of computing and telecommunications...
.
For example, the HP 21MX
HP 2100
The HP 2100 was a series of minicomputers produced by Hewlett-Packard from the mid-1960s to early 1990s. The 2100 was also a specific model in this series. The series was renamed HP 1000 by the 1970s and sold as real-time computers, complementing the more complex IT-oriented HP 3000, and would be...
real-time computer (1974) denoted 196,608 (which is 192×1024) as "196K",
while the HP 3000
HP 3000
The HP 3000 series is a family of minicomputers released by Hewlett-Packard in 1973. It was designed to be the first minicomputer delivered with a full featured operating system with time-sharing. The first models were withdrawn from the market until speed improvements could be made. It ultimately...
business computer (1973) denoted 131,072 (which is 128×1024) as "128K".
The Shugart
Shugart Associates
Shugart Associates was a computer peripheral manufacturer that dominated the floppy disk drive market in the late 1970s and is famous for introducing the 5¼-inch minifloppy disk drive....
SA-400 5¼-inch floppy drive (1977) held 109,375 bytes unformatted, and was advertised as "110 Kbyte", using the 1000 convention. Likewise, the DEC RX01 (1975) held 256,256 bytes formatted, and was advertised as "256k". On the other hand, the Tandon 5¼-inch DD floppy format (1978) held 368,640 bytes, but was advertised as "360 KB", following the 1024 convention.
On modern systems, Mac OS X Snow Leopard represents a 65,536 byte file as "66 KB", while Microsoft Windows 7 would represent this as "64 KB".
In December 1998, the IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
attempted to address these dual definitions of the conventional prefixes by proposing unique binary prefixes and prefix symbols to denote multiples of 1024, such as “kibibyte
Kibibyte
The kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 1024; therefore, 1 kibibyte is . The unit symbol for the kibibyte is KiB. The unit was established by the International Electrotechnical Commission in 1999 and has been accepted for use...
(KiB)”, which exclusively denotes 210 or 1024 bytes. If the proposal had been widely and consistently adopted, it would have liberated the standard unit prefixes to unambiguously refer only to their strict decimal definitions wherein kilobyte would be understood to represent only 1000 bytes. However, in the over that have since elapsed, the proposal has seen little adoption by the computer industry.
Examples of use
- 1 kilobyte: (very) short story
- 2 kilobytes: typewritten page
- 10 kilobytes: page out of an encyclopedia
See also
- kibibyteKibibyteThe kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 1024; therefore, 1 kibibyte is . The unit symbol for the kibibyte is KiB. The unit was established by the International Electrotechnical Commission in 1999 and has been accepted for use...
- Data rate unitsData rate unitsIn telecommunications, bit rate or data transfer rate is the average number of bits, characters, or blocks per unit time passing between equipment in a data transmission system. This is typically measured in multiples of the unit bit per second or byte per second.- Avoiding confusion :To be as...
- Timeline of binary prefixesTimeline of binary prefixesThis article presents a terminology timeline of binary prefixes. Early computers used two different approaches to memory addressing, representing the address as either a binary number or as a decimal number. Early machines that used decimal addressing included the ENIAC, UNIVAC 1, IBM 702, IBM 705,...
- History of the floppy diskHistory of the floppy diskOver the history of the floppy disk a number of different formats were used. Floppy disks have now been largely superseded by other storage media and by network file transfer.-Origins, the 8-inch disk:...