Megabit
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|---|---|---|---|---|
| SI prefixes | Binary prefixes | |||
| Name (Symbol) |
Standard SI |
Binary usage |
Name (Symbol) |
Value |
| kilobit (kbit) | 103 | 210 | kibibit (Kibit) | 210 |
| megabit (Mbit) | 106 | 220 | mebibit (Mibit) | 220 |
| gigabit (Gbit) | 109 | 230 | gibibit (Gibit) | 230 |
| terabit (Tbit) | 1012 | 240 | tebibit (Tibit) | 240 |
| petabit (Pbit) | 1015 | 250 | pebibit (Pibit) | 250 |
| exabit (Ebit) | 1018 | 260 | exbibit (Eibit) | 260 |
| zettabit (Zbit) | 1021 | 270 | zebibit (Zibit) | 270 |
| yottabit (Ybit) | 1024 | 280 | yobibit (Yibit) | 280 |
A megabit is a SI-multiple (see prefix mega) of the unit of bit for digital information storage or transmission, abbreviated Mbit (or Mb).
1 megabit = 10002 bits = 106 bits = 1000000bits.
Based on an eight-bit-sized byte this is equal to 125000bytes, 125 kilobytes (kB), or approximately 122 kibibytes (KiB).
The megabit is most commonly used when referring to data transfer rates of networks or telecommunications systems, e.g., a 100 Mbit/s (megabit per second) Fast-Ethernet connection. Residential high-speed Internet access is often advertised incorrectly in megabits, a unit of information quantity, rather than rate in megabit per second.
The binary-interpreted counterpart of the megabit, the mebibit (Mib), refers to the quantity of 10242 bits = 1048576bits.
[edit] Usage conventions
- In Telecommunications, use of the correct SI definition of the unit is standard.
- Standard industry practice in RAM and ROM manufacture has been to use the Mb abbreviation in reference to the binary interpretation of the megabit. For example, a single discrete DDR3 chip specified at 512Mb invariably contains 229 bits = 536870912bits = 512 Mibit of storage,[1] or 671088648-bit bytes, variously referred to as either 64 mebibytes or 64 (binary) megabytes.
- In the 16-bit game console era, the 'megabit' became a commonly-used measure of the size (computer data storage capacity) of game cartridges. This "megabit" actually equals one mebibit (Mibit). The vast majority of SNES and Sega Mega Drive (Genesis) games were produced on standard 8 megabit cartridges, although 4 megabit cartridges were not uncommon and, later in the life of these consoles, graphically-intensive titles would appear on 12, 16, 24, even 32 megabit cartridges. Tales of Phantasia and Star Ocean were 48 megabit and released only in Japan. The standard rule is: 8 bits = 1 byte. Therefore a 4 megabit cartridge had a capacity of 512 KiB, an 8 megabit cartridge held 1 MiB of data.
[edit] See also
[edit] References
- ^ "JEDEC Standard DDR3 SDRAM Specification" (PDF, 8.8 MB). http://www.jedec.org/download/search/JESD79-3A.pdf. Retrieved on 2008-07-10.
