Bits, Bytes and Bandwidth Reference Guide - Abbreviations Table (knowledge - 電腦)

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SpeedGuide_net: Bits, Bytes and Bandwidth Reference Guide

Bits, Bytes and Bandwidth Reference Guide

2001.01.01 01:53 by Philip
Keywords: bit, byte, conversion

Quick Conversions...

For a quick reference, ue our Bits/Bytes Conversion Calculator.

For the few people that care to learn it right (or be confused to death), read on ;)

The Bits vs. Bytes Confusion

Let's start with some background information on prefixes, by mentioning the Metric system:

• kilo (k)* = 10 ^ 3 = 1,000 thousand
• mega (M) = 10 ^ 6 = 1,000,000 million
• giga (G) = 10 ^ 9 = 1,000,000,000 billion
• tera (T) = 10 ^ 12 = 1,000,000,000,000 trillion

* Note that according to the Metric system, the "k" or "kilo" prefix is always lowercase.
The binary forms of kilobytes and megabytes have become standard throughout the computer industry, although they are incorrect uses of the SI prefixes (in the IT field lowercase "k" is used to describe decimal kilobits, and capital "K" is used for binary kilobytes).


When used to describe Data Transfer Rate, bits/bytes are calculated as in the metric system

In data communications, a kilobit is a thousand bits, or 1,000 bits. It's commonly used for measuring the amount of data that is transferred in a second between two telecommunication points. Kilobits per second is usually shortened to kbps or Kbps**. Some sources define a kilobit to mean 1,024 bits. Although the bit is a unit of the binary number system, bits in data communications are discrete signal pulses and have historically been counted using the decimal number system. For example, 28.8 kilobits per second (kbps) is 28,800 bits per second.

• 1 bit (b) = 0 or 1 = one binary digit
• 1 kilobit ( kb) = 10^3 bits = 1,000 bits
• 1 Megabit (Mb) = 10^6 bits = 1,000,000 bits
• 1 Gigabit (Gb) = 10^9 bits = 1,000,000,000 bits

** Note:  Although technically speaking, the term kilobit should have a lowercase initial letter, most published reports capitalize it in abbreviation, resulting in "56 Kbps," or even the really confusing "56K."  That leaves you with the sometimes omitted lowercase "b" to distinguish between bits (b) and bytes (B). When used as a measurement of network data transfers, or throughput, always assume the word is bits first.

When used to describe Memory Size, or Data Storage bits/bytes are generally calculated as some exponent of 2

In Data storage, and when describing Memory size, a Kilobyte is 2^10, or 1024 bytes. Because of binary computer architecture and memory address boundaries, bytes are always some multiple or exponent of two.

• 1 byte (B) = 8 bits (b)
• 1 Kilobyte (K / KB) = 2^10 bytes = 1,024 bytes
• 1 Megabyte (M / MB) = 2^20 bytes = 1,048,576 bytes
• 1 Gigabyte (G / GB) = 2^30 bytes = 1,073,741,824 bytes
• 1 Terabyte (T / TB) = 2^40 bytes = 1,099,511,627,776 bytes

Although data storage capacity, such as on hard drives is generally expressed in binary Megabytes (2^20), most Hard disk manufacturers, and some newer BIOSes use decimal megabytes (10^6), which is slightly different and it gets confusing...

• 1 byte (B) = 8 bits (b)
• 1 Kilobyte (K / KB) = 10^3 bytes = 1,000 bytes
• 1 Megabyte (M / MB) = 10^6 bytes = 1,000,000 bytes
• 1 Gigabyte (G / GB) = 10^9 bytes = 1,000,000,000 bytes
• 1 Terabyte (T / TB) = 10^12 bytes = 1,000,000,000,000 bytes

Abbreviations Table
 

bit	b	0 or 1
byte	B	8 bits
kilobit	kb	1000 bits
kilobyte (binary)	KB	1024 bytes
kilobyte (decimal)	KB	1000 bytes
Megabit	Mb	1000 kilobits
Megabyte (binary)	MB	1024 Kilobytes
Megabyte (decimal)	MB	1000 Kilobytes
Gigabit	Gb	1000 Megabits
Gigabyte (binary)	GB	1024 Megabytes
Gigabyte (decimal)	GB	1000 Megabytes

Bandwidth Reference Table

DS0 (digital signal 0) is digital transmission rate of 64 Kbps, the bandwidth normally used for one telephone voice channel. It is the base multiple for both T (North America) and E (Europe) DS (digital signal) carriers.

The following table summarizes the set of signals and their relationship to the T-carrier and E-carrier systems

SG Bandwidth Reference Table
DSx / Ex / Jx	Data rate	DS0 multiple	Carrier
DS0(E0/J0)	64 kbps	1
	128 kbps	2	ISDN
DS1	1.544 Mbps	23 (24)	T1
E1	2.048 Mbps	30 (32)	E1
DS1C / J1C	3.152 Mbps	46 (48)	T1C / J1C
DS2 / J2	6.312 Mbps	92 (96)	T2 / J2
E2	8.448 Mbps	120 (132)	E2
J3	32.064 Mbps	480	J3
E3	34.368 Mbps	480 (537)	E3
DS3	44.736 Mbps	644 (672)	T3
STS1	51.84 Mbps	672	OC1
DS3C	89.472 Mbps	1288 (1344)	T3C
J4	97.728 Mbps	1440	J3C
DS3X	134.208 Mbps	1932 (2016)	T3X
E4	139.264 Mbps	1920 (2148)	E4
STS-3 / SDH-1	155.52 Mbps	2016	OC3
DS4	274.176 Mbps	3864 (4032)	T4
J5	400.352 Mbps	5760	J4
DS4E	411.264 Mbps	5796 (6048)	T4E
STS-9 / SDH-3	466.56 Mbps	6048	OC9
DS4C	560.160 Mbps	7728 (8064)	T4C
E5	565.148 Mbps	7680 (8592)	E5 (4 E4 chnnels)
STS-12 / SDH-4	622.08 Mbps	8064	OC12
DS4X	822.528 Mbps	11592 (12096)	T4X
STS-18 / SDH-6	933.12 Mbps	12096	OC18
DS5	1.120 Gbps	15456 (16128)	T5
STS-24 / SDH-8	1.244 Gbps	16128	OC24
DS5X	1.400 Gbps	19320 (20160)	T5X
DS5E	1.680 Gbps	23184 (24192)	T5E
STS-36 / SDH-12	1.866 Gbps	24192	OC36
STS-48 / SDH-16	2.488 Gbps	32256	OC48
STS-96 / SDH-32	4.976 Gbps	64512	OC96
STS-192 / SDH-64	9.952 Gbps	129024	OC192
STS-256	13.271 Gbps	172032	OC256
STS-768 / SDH-256	39.813 Gbps	516096	OC768

Note: The following digital signal levels are not standardized and/or are not in common use:
DS3C, DS3X, DS4E, DS4C, DS4X, DS5, DS5X, DS5E, E5, J5, STS-9, STS-18, STS-24, STS-36, STS-256, STS-768.





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