Most significant bit
Encyclopedia
In computing
, the most significant bit (msb, also called the high-order bit) is the bit
position in a binary number
having the greatest value. The msb is sometimes referred to as the left-most bit due to the convention in positional notation
of writing more significant digits further to the left.
The msb can also correspond to the sign
of a signed binary number in one or two's complement notation. "1" meaning negative and "0" meaning positive.
It is common to assign each bit a position number, ranging from zero to N-1, where N is the number of bits in the binary representation used. Normally, this is simply the exponent for the corresponding bit weight in base-2 (such as in
the opposite way (which is not the same as different endianness
), the msb unambiguously remain the most significant bit. This may be one of the reasons why the term msb is often used instead of a bit number, although the primary reason is probably that different number representations use different numbers of bits.
By extension, the most significant bits (plural) are the bits closest to, and including, the msb.
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, the most significant bit (msb, also called the high-order bit) is the bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
position in a binary number
Binary numeral system
The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...
having the greatest value. The msb is sometimes referred to as the left-most bit due to the convention in positional notation
Positional notation
Positional notation or place-value notation is a method of representing or encoding numbers. Positional notation is distinguished from other notations for its use of the same symbol for the different orders of magnitude...
of writing more significant digits further to the left.
The msb can also correspond to the sign
Sign bit
In computer science, the sign bit is a bit in a computer numbering format that indicates the sign of a number. In IEEE format, the sign bit is the leftmost bit...
of a signed binary number in one or two's complement notation. "1" meaning negative and "0" meaning positive.
It is common to assign each bit a position number, ranging from zero to N-1, where N is the number of bits in the binary representation used. Normally, this is simply the exponent for the corresponding bit weight in base-2 (such as in
231..20). Although a few CPU manufacturers assign bit numbersBit numbering
In computing, bit numbering is the convention used to identify the bit positions in a binary number or a container for such a value...
the opposite way (which is not the same as different endianness
Endianness
In computing, the term endian or endianness refers to the ordering of individually addressable sub-components within the representation of a larger data item as stored in external memory . Each sub-component in the representation has a unique degree of significance, like the place value of digits...
), the msb unambiguously remain the most significant bit. This may be one of the reasons why the term msb is often used instead of a bit number, although the primary reason is probably that different number representations use different numbers of bits.
By extension, the most significant bits (plural) are the bits closest to, and including, the msb.
Other uses
MSB, in all capitals, can also stand for "most significant byte". The meaning is parallel to the above: it is the byte (or octet) in that position of a multi-byte number which has the greatest potential value.See also
- Least significant bitLeast significant bitIn computing, the least significant bit is the bit position in a binary integer giving the units value, that is, determining whether the number is even or odd. The lsb is sometimes referred to as the right-most bit, due to the convention in positional notation of writing less significant digits...
- Binary numeral systemBinary numeral systemThe binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...
- Signed number representationsSigned number representationsIn computing, signed number representations are required to encode negative numbers in binary number systems.In mathematics, negative numbers in any base are represented by prefixing them with a − sign. However, in computer hardware, numbers are represented in binary only without extra...
- Two's complementTwo's complementThe two's complement of a binary number is defined as the value obtained by subtracting the number from a large power of two...
- Bit numberingBit numberingIn computing, bit numbering is the convention used to identify the bit positions in a binary number or a container for such a value...
- EndiannessEndiannessIn computing, the term endian or endianness refers to the ordering of individually addressable sub-components within the representation of a larger data item as stored in external memory . Each sub-component in the representation has a unique degree of significance, like the place value of digits...