Memory Calculation :
From Wikipedia, the free encyclopedia
The megabyte is a multiple of the unit byte for digital information storage or transmission with three different values depending on context: 1048576 bytes (220) generally for computer memory; and one million bytes (106, see prefix mega-) generally for computer storage. In rare cases, it is used to mean 1000×1024 (1024000) bytes.[3] The IEEE Standards Board has confirmed that mega- means 1000000, with exceptions allowed for the base-two meaning.It is commonly abbreviated as Mbyte or MB (compare Mb, for the megabit).
The Terabyte is a multiple of the unit byte for digital information. The prefix tera means 1012 in the International System of Units (SI), and therefore 1 terabyte is 1000000000000bytes, or 1 trillion (short scale) bytes, or 1000 gigabytes. 1 terabyte in binary prefixes is 0.9095 tebibytes, or 931.32 gibibytes. The unit symbol for the terabyte is TB or TByte, but not Tb (lower case b) which refers to terabit.
From Wikipedia, the free encyclopedia
| Prefixes for multiples of bits (b) or bytes (B) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
The kilobyte (symbol: kB) is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol kB or 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.[1][2][3]
For example:
- The HP 21MX real-time computer (1974) denoted 196,608 (which is 192×1024) as "196K",[4] while the HP 3000 business computer (1973) denoted 131,072 (which is 128×1024) as "128K".[5]
- The Shugart SA-400 51⁄4-inch floppy disk (1976) held 109,375 bytes unformatted,[6] and was advertised as "110 Kbyte", using the 1000 convention.[7] Likewise, the 8-inch DEC RX01 floppy (1975) held 256,256 bytes formatted, and was advertised as "256k".[8] On the other hand, the Tandon 51⁄4-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",[9] rounding to the nearest 1000, while Microsoft Windows 7 would divide by 1024 and represent this as "64 KB".[10]
In December 1998, the IEC addressed such multiple usages and definitions by creating unique binary prefixes to denote multiples of 1024, such as “kibibyte (KiB)”, which represents 210, or 1024, bytes.[11] However, adoption by the computer industry has not been universal, particularly when communicating in a public context, such as to consumers of computer or computer based products.
| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
| The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units (SI), therefore 1 gigabyte is 1000000000bytes. The unit symbol for the gigabyte is GB or Gbyte, but not Gb (lower case b) which is typically used for the gigabit. | ||||
Historically, the term has also been used in some fields of computer science and information technology to denote the gibibyte, or 1073741824 (10243 or 230) bytes. The Institute of Electrical and Electronics Engineers (IEEE) defined the unit accordingly for the use in power switchgear.[2] In 2000, however, IEEE adopted the International Electrotechnical Commission (IEC) recommendation, which uses the metric prefix interpretation.
Today the usage of the unit gigabyte continues to depend on the context. When referring to disk storage capacities it usually means 109 bytes, often stated explicitly on the manufacturer's permanent sticker. This also applies to data transmission quantities over telecommunication circuits, as the telecommunications and computer networking industries have always used the SI prefixes with their standards-based meaning. When referring to RAM sizes it most often (see binary prefix adoption) has a binary interpretation of 10243 bytes, i.e. as an alias for gibibyte. File systems and software often list file sizes or free space in some mixture of SI units and binary units; they sometimes use SI prefixes to refer to binary interpretation – that is using a label of gigabyte or GB for a number computed in terms of gibibytes (GiB), continuing the confusion.
In order to address this the International Electrotechnical Commission has been promoting the use of the term gibibyte for the binary definition. This position is endorsed by other standards organizations including the IEEE, the International Committee for Weights and Measures (CIPM) and the U.S. National Institute of Standards and Technology (NIST), but the binary prefixes have seen limited acceptance. The JEDEC industry consortium continues to recommend the IEEE 100 nomenclature of using the metric prefixes kilo, mega and giga in their binary interpretation for memory manufacturing designations.
| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
A petabyte (derived from the SI prefix peta- ) is a unit of information equal to one quadrillion (short scale) bytes, or 1000 terabytes. The unit symbol for the petabyte is PB. The prefix peta (P) indicates the fifth power to 1000:
- 1 PB = 1000000000000000B = 10005 B = 1015 B = 1 million gigabytes = 1 thousand terabytes
The pebibyte (PiB), using a binary prefix, is the corresponding power of 1024, which is more than 12% greater (250 bytes = 1125899906842624bytes).
| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
| The exabyte (derived from the SI prefix exa-) is a unit of information or computer storage equal to one quintillion bytes (short scale). The unit symbol for the exabyte is EB. The unit prefix exa indicates the sixth power of 1000: | ||||
- 1 EB = 1000000000000000000B = 1018 bytes = 1000000000gigabytes = 1000000terabytes
The exbibyte, using a binary prefix, is the analogous power of 1024 bytes.
In principle, the 64-bit microprocessors found in many computers can address 16 exbibytes, or just over 18 exabytes, of memory.
| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
A zettabyte (symbol ZB, derived from the SI prefix zetta-) is a unit of information or computer storage equal to one sextillion (one long scale trilliard) bytes.[1][2][3][4]
As of March 2012, no storage system has achieved one zettabyte of information. The combined space of all computer hard drives in the world was estimated at approximately 160 exabytes in 2006.[5] This has increased rapidly however, as during the 2011 Fiscal Year, Seagate reported selling a combined total of 330 exabytes of hard drives. This does not include shipments from any other manufacturer, and only includes those sold during 2011. [6] As of 2009, the entire Internet was estimated to contain close to 500 exabytes.This is a half zettabyte.
- 1,000,000,000,000,000,000,000 bytes = 10007 bytes = 1021 bytes
The term "zebibyte" (ZiB), using a binary prefix, is used for the corresponding power of 1024.
| Multiples of bytes | ||||
|---|---|---|---|---|
| SI decimal prefixes | Binary usage | IEC binary prefixes | ||
| Name (Symbol) | Value | Name (Symbol) | Value | |
| kilobyte (kB) | 103 | 210 | kibibyte (KiB) | 210 |
| megabyte (MB) | 106 | 220 | mebibyte (MiB) | 220 |
| gigabyte (GB) | 109 | 230 | gibibyte (GiB) | 230 |
| terabyte (TB) | 1012 | 240 | tebibyte (TiB) | 240 |
| petabyte (PB) | 1015 | 250 | pebibyte (PiB) | 250 |
| exabyte (EB) | 1018 | 260 | exbibyte (EiB) | 260 |
| zettabyte (ZB) | 1021 | 270 | zebibyte (ZiB) | 270 |
| yottabyte (YB) | 1024 | 280 | yobibyte (YiB) | 280 |
The yottabyte (derived from the SI prefix yotta-) is a unit of information or computer storage equal to one septillion (one long scale quadrillion or 1024) bytes (one quadrillion gigabytes). The unit symbol for the yottabyte is YB.
As of 2011, no storage system or network has achieved even one thousandth of a yottabyte (a zettabyte) of information. The combined space of all computer hard drives in the world was estimated at approximately 160 exabytes in 2006[1], and as of 2009, the Internet was estimated to contain close to 500 exabytes.[2]
When used with byte multiples, the SI prefix indicates a power of 1000:
- 1000000000000000000000000bytes = 10008 or 1024 bytes
The term "yobibyte" (YiB), using a binary prefix, is used for the corresponding power of 1024.
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