All photographs, text documents and programs are stored in computer memory in the form of bits and bytes. What are these smallest units of information and how many bits are in a byte?
Storing data in memory
Computer memory is a huge collection of cells filled with zeros and ones. A cell is the minimum amount of data that a reader can access. Physically, it is a trigger (in modern computers). The trigger is so small that it is difficult to see even under a microscope. Each cell has a unique address at which one or another program finds it.
A cell in most cases means one byte. But, depending on the capacity of the architecture, it can combine 2, 4 or 8 bytes. Byte is perceived by electronic devices as a whole, but in fact it consists of even smaller cells - bits. In 1 byte, you can encode a character, for example, a letter or a number, while 1 bit is not enough for this.
Controllers rarely operate on individual bits, although this is technically possible. Instead, it refers to whole bytes or even groups of bytes.
What is a bit?
Often, by bit is meant a unit of information. This definition cannot be called accurate, because the very concept of information is rather vague. If to speak more correctly, then a bit is a letter of a computer alphabet. The word "bit" comes from the English expression "binary digit", which literally means "binary digit".
The alphabet of computers is simple and consists of only two characters: 1 and 0 (the presence or absence of a signal, true or false). This set is quite enough to logically describe anything. The third condition, which is understood as computer silence (cessation of signal transmission), is a myth.
The letter itself does not carry any value in terms of information: looking at a unit or zero, it is impossible to understand even what kind of data this value refers to. And photos, and texts, and programs ultimately consist of ones and zeros. Therefore, a bit is inconvenient as an independent unit. Therefore, the bits must be combined in order to encode useful information with their help.
What is a byte?
If a bit is a letter, then a byte is like a word. One byte may contain a text character, an integer, part of a large number, two small numbers, etc. Thus, the byte already contains meaningful information, albeit in a small amount.
Novice programmers and simply curious users are interested in how many bits are in 1 byte. In modern computers, one byte is always equal to eight bits.
If a bit is capable of taking only two values, then a combination of eight bits can create 256 different combinations. The number 256 is formed by raising the two to the eighth power (in accordance with how many bits in a byte).
One bit is 1 or 0. Two bits can already create combinations: 00, 01, 10 and 11. When it comes to 8 bits, then combinations of zeros and ones in the range 00000000 ... 11111111 turn out to be exactly 256. If you remember , how many values can take and how many bits are contained in one byte, it will be very easy to remember this figure.
Each combination of characters can carry different information depending on the encoding (ASCII, Unicode, etc.). That is why users are faced with the fact that information entered in Russian is sometimes displayed in the form of intricate characters.
Features of the binary number system
The binary system has all the same properties as the familiar decimal: numbers consisting of ones and zeros can be added, subtracted, multiplied, etc. The only difference is that the system does not consist of 10, but of 2 digits. That is why it is convenient to use it to encrypt information.
In any positional calculus, numbers consist of digits: units, tens, hundreds, etc. In the decimal system, the maximum value of one digit is 9, and in the binary system - 1. Since one digit can take only two values, binary numbers quickly increase in length. For example, the familiar number 9 will be written as 1001. This means that the nine will be recorded with four characters, while one binary character will correspond to one bit.
Why is information encrypted in binary form?
The decimal system is convenient for inputting and outputting information, and the binary system is convenient for organizing the process of its transformation. Systems that contain eight and sixteen characters are also very popular: they translate machine codes into a convenient form.
The binary system is most convenient in terms of logic. The unit conditionally means “yes”: there is a signal, the statement is true, etc. Zero is associated with the value “no”: the value is false, there is no signal, etc. Any open-ended question can be converted into one or more questions with answer options “yes” " or not". The third option, for example, "unknown", will be completely useless.
During the development of computer technology, three-digit capacities for storing information called trits were also developed. They can take three values: 0 - capacity is empty, 1 - capacity is half full and 2 - full capacity. However, the binary system turned out to be simpler and more logical, and therefore received much greater popularity.
How many bits in a byte were there before?
Previously, it was impossible to say unambiguously how many bits in a byte. Initially, byte was understood as a machine word, that is, the number of bits that a computer can process in one working cycle (cycle). When computers were not yet placed in workrooms, different microprocessors worked with bytes of various sizes. A byte could include 6 bits, and in the first IBM models, its size reached 9 bits.
Today, 8-bit bytes have become so familiar that even the definition of a byte often says that it is a unit of information consisting of 8 bits. However, in a number of architectures, a byte equals 32 bits and acts as a machine word. Such architectures are used in some supercomputers and signal processors, but not on the usual computers, laptops and mobile phones.
Why did the eight-bit standard win?
The bytes acquired an eight-bit size thanks to the IBM PC platform with the popular 80-bit Intel 8086 processor. The prevalence of this model contributed to the fact that in the 1970s. 8 bits per byte has actually become the standard value.
The eight-bit standard is convenient in that it allows you to store two characters of the decimal system in 1 byte. With a 6-bit system, one digit can be stored, while 2 bits are redundant. In 9 bits, you can write 2 digits, but still one extra bit remains. The number 8 is the third power of two, which provides additional convenience.
Scopes of bits and bytes
Many users are wondering: how not to mix bit and byte? First of all, you need to pay attention to how the designation is written: in abbreviated form, the byte is written in the form of a capital letter "B" (in English - "B"). Accordingly, a small letter "b" ("b") is used to designate a bit.
However, there is always the possibility that the case is not selected correctly (for example, some programs automatically translate all text into lower or upper case). In this case, you should know what is usually measured in bits, and what in bytes.
Traditionally, bytes are measured in volumes: the size of the hard drive, flash drive, and any other medium will be indicated in bytes and enlarged units, for example, gigabytes.
Bits are used to measure speed. The amount of information that the channel passes, the speed of the Internet, etc., are measured in bits and derived units, for example, megabits. File download speed is also always displayed in bits.
If desired, you can translate bits into bytes or vice versa. To do this, just remember how many bits are in a byte, and perform a simple mathematical calculation. Bits are converted to bytes by dividing by eight, the reverse translation is carried out by multiplying by the same number.
What is a machine word?
A machine word is information recorded in a memory cell. It represents the maximum sequence of units of information that is processed as a whole.
The word length corresponds to the capacity of the processor, which for a long time has been equal to 16 bits. On most modern computers, it is 64 bits, although there are shorter (32 bits) and longer machine words. Moreover, the number of bits forming a machine word is always a multiple of eight and can be easily converted to bytes.
For a particular computer, the word length is unchanged and belongs to a number of the most important characteristics of hardware.