Computer Science
Bit
A bit is the smallest unit of data in computing and digital communications. It can have a value of either 0 or 1, representing the binary state of off or on, respectively. Bits are used to encode and process information in digital systems, and they form the basis for representing and manipulating data in computer science.
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6 Key excerpts on "Bit"
eBook - ePub- Douglas Comer(Author)
- 2017(Publication Date)
- Chapman and Hall/CRC(Publisher)
stored program computers because programs as well as data are placed in memory. We will discuss program representation and storage in the next chapters, including the structure of instructions the computer understands and their storage in memory. For now, it is sufficient to understand that each computer defines a specific set of operations and a format in which each is stored. On some computers, for example, each instruction is the same size as other instructions; on other computers, the instruction size varies. We will see that on a typical computer, an instruction occupies multiple bytes. Thus, the Bit and byte numbering schemes that the computer uses for data values also apply to instructions.3.23 Summary
The underlying digital hardware has two possible values, logical 0 and logical 1. We think of the two values as defining a Bit (binary digit), and use Bits to represent data and programs. Each computer defines a byte size, and most current systems use eight Bits per byte.A set of Bits can be used to represent a character from the computer’s character set, an unsigned integer, a single or double precision floating point value, or a computer program. Representations are chosen carefully to maximize the flexibility and speed of the hardware while keeping the cost low. The two’s complement representation for signed integers is particularly popular because a single piece of hardware can be constructed that performs operations on either two’s complement integers or unsigned integers. In cases where decimal arithmetic is required, computers use Binary Coded Decimal values in which a number is represented by a string that specifies individual decimal digits.
eBook - ePubCybercrime and Information Technology
Theory and Practice: The Computer Network Infostructure and Computer Security, Cybersecurity Laws, Internet of Things (IoT), and Mobile Devices
- Alex Alexandrou(Author)
- 2021(Publication Date)
- CRC Press(Publisher)
Figure 1.5 ).FIGURE 1.5 A research to improve the human–computer interface, c1966. MAGIC (Machine for Automatic Graphics Interface to a Computer) Photograph from NIST Digital Archives.Understanding Binary Data
Human languages use characters or symbols, letters and images to signify meaning. These characters are unintelligible to the wires and circuits within the computer. The computer does not act as we do; instead, it stores values as electrical charges. More specifically, when electricity flows through a wire, the electrical signal can be represented as either 1 or 0, True or False, Yes or No, or On or Off. Figure 1.6 demonstrates the binary representation of an image.FIGURE 1.6 The Binary representation of an image.The 0 or 1 is referred to as a Bit (short for binary digit), and is the smallest unit of information. The more electrical connections the computer uses, the more Bits are flowing through its system.While a Bit can represent only a 0 or a 1, a byte, a collection of exactly 8 Bits, represents a unique character. Table 1.1 and Figure 1.7 demonstrate the possible patterns or states of 0s and 1s that can be made from 1, 2, 3 and 4 Bits.TABLE 1.1 Bits and Their Possible PatternsBits Possible Patterns 1 Bit (2 possible values) 0 or 1 2 Bits (4 values) 00 01 10 11 3 Bits (8 values) 000 001 010 011 100 101 110 111 FIGURE 1.7 Bits possible patterns.To be able to represent more than 1 and 0, True/False, Yes/No, or On/Off, we collect 8 Bits to form 1 byte. With 1 byte we can represent and store the numbers between 0 and 255 (28 ). Therefore, a single byte can represent up to 256 different values.By arranging Bits into bytes, any number up to 255 can be represented using only 0s and 1s. Overall, each additional Bit doubles the number of possible patterns (Table 1.2
- R. Balakrishnan, Sriraman Sridharan(Authors)
- 2018(Publication Date)
- Chapman and Hall/CRC(Publisher)
Algorithms exist independent of any computer. In the absence of a computer it is the human being who plays the role of a machine. Of course, humans are subject to errors, fatigue, etc., whereas computers can execute long sequences of instructions with reliability, and with thoughtless obedience.The modern digital computer was invented to facilitate difficult, long and tedious calculations. A computer is only a machine which manipulates a material called “information.” Information can be described as a finite sequence of letters, digits, and some special characters like *, +, :, etc.The information manipulated by a computer must be:1. Stored : This is the role of the memory.2. Manipulated : This is the role of the Central Processing Unit.3. Exchanged (with a programmer or with other machines): This is the role of the input/output peripheral units like the keyboard and monitor.In the figure below, a model of a classical computer is depicted (see [7 ]).Main memoryFigure 5.2 A model of a classic computerInformation is stored in memory as a sequence of Bits (binary digits ). A binary digit is either 0 or 1. In fact, the information manipulated by a computer is materialized by two different voltages (0 means a high voltage, 1 means a low voltage, for example) in the computer’s circuitry. The smallest storage unit of memory is referred to as a cell or a byte . We may treat a byte as a box containing a small chunk of information. Each byte possesses an address which distinguishes it from the other bytes. In fact, the addresses of the bytes are the non-negative integers starting from 0,1,... and ending withwhere n is the number of bytes in the main memory . Thus a byte is the smallest storage unit which has its own address, that is, the smallest addressable unit of memory. Usually a byte is a sequence of 8 Bits.n - 1It is generally 8, 16, 24 or 32 Bits under high/low voltage. The set of all bytes is referred to as the main memory. In the main memory, the computer stocks not only the sequence of statements comprising a program, indicating the manipulation/computation to be carried out on the data , but also the data on which these statements of the program will be executed. The following parameters are associated with the memory: 1. The capacity or size of the memory. 2. The speed with which the instructions can be stocked and retrieved. The main memory is also called the Random Access Memory
eBook - ePubExploring Computer Hardware
The Illustrated Guide to Understanding Computer Hardware, Components, Peripherals & Networks
- Kevin Wilson(Author)
- 2022(Publication Date)
- Elluminet Press(Publisher)
Computer Fundamentals
A computer is a machine that can store and process data according to a sequence of instructions called a program. At their most fundamental level, these machines can only process binary data: 1s and 0s. In this chapter, we’ll take a look at using the binary code to encode data, as well as binary arithmetic and number bases. We’ll look at using logic gates to build simple circuits and how they form the building blocks for electronic devices, before moving onto the fetch execute cycle and instruction sets. Have a look at the video demos to help you understand. Open your web browser and navigate to the following website:elluminetpress.com/ funda
Passage contains an image
Representing Data
The computer uses 1s and 0s to encode computer instructions and data. RAM is essentially a bank of switches: ‘off’ represents a 0 and ‘on’ represents a 1. Using this idea, data can be encoded using either ASCII or Unicode and stored in RAM or on a disc drive. Passage contains an image
ASCII code
The American Standard Code for Information Interchange (ASCII), originally used a 7-Bit binary code to represent letters, numbers and other characters. Each character is assigned a binary number between 0 to 127. For example:Capital A is 010000012 (6510 )Lowercase a is 011000012 (9710 )000-31 is reserved for control characters such as end of line, carriage returns, end of text, and so on. 032-126 covers symbols, numbers 0-9, and all lowercase and uppercase letters. The ASCII code set was later extended to 8-Bit which allowed more characters to be encoded. These included mathematical symbols, international characters and other special characters needed. Passage contains an image
Unicode
Unicode is a universal encoding standard for representing the characters of all the languages of the world, including those with larger character sets such as Chinese, Japanese, and Korean.UTF-8 is a variable length encoding system that uses one to four bytes to represent a character. UTF-8 is backwards compatible with ASCII and widely used in internet web pages. In your HTML code you might see something like this: <meta charset=”utf-8”>
eBook - ePub- Don Davis, Eugene Patronis, Pat Brown(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
The wave patterns that describe protons, neutrons, and their relatives resemble the vibration patterns of musical instruments. In fact the mathematical equations that govern these superficially very different realms are quite similar.Some physicists today have described reality as “It’s from Bits.” Where Newtonians saw the universe as some form of giant mechanism, and early computer enthusiasts saw the universe as a form of giant computer, it is increasingly viewed as some form of Information. The singularity problem provides interesting reading where those who are sharing deep thinking about the role of information in our lives describe the undesirable possibilities of artificial intelligences governing man.5.5 Digital Nomenclature
Table 5-1 is a list of the most popular nomenclatures used in digital circuitryTable 5-1 Digital NomenclatureBit binary digit Nibble 4 Bits Byte 8 Bits Word 16 Bits Double word 32 Bits Quad word 64 Bits Binary base 2, log2Octal base 8, log8Denary base 10, log10Hexadecimal base 16, log16MSB most significant Bit LSB least significant Bit Bit rate Bits × sampling frequency × channels SNR signal-to-noise ratio, 10 × log10 (6 × (2(b − 2) )FLOP floating point operations per second MIPS million instructions per second MIPW million instructions per watt RISC reduced instruction set computer WAV wave format BWF broadcast wave format CPU central processing unit GPU graphics processing unit PCM pulse code modulation PDF portable document format ASCII American Standard Code for Information Interchanges CD compact disc DVD digital versatile disc MPEG motion picture experts group ISO International Organization for Standardization AAC advanced audio coding MDCT modified discrete cosine transform TNS temporal noise shaping HDTV high-definition television VBR variable Bit rate CBR constant Bit rate Codec compressor/decompressor IO input – output Fs sampling frequency V/2BitsQuantization level DSP digital signal processor ADC analog to digital converter DAC digital to analog converter ERB equivalent rectangular bandwidth HTML hypertext markup language 
- Ross Kirk, Andy Hunt(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
We now have an understanding of the way in which digital audio signals are represented, manipulated and stored. It is therefore appropriate to gain an understanding of the digital machines, particularly the computer, which carry out this processing.In this chapter we will look at the nature of the information handled within computer systems, and at the circuits which deal with, and store this information. These circuits will then form the basis of our understanding of the structure of computer systems, which will be introduced in Chapters 7 and 8 .6.1 Elementary logic and binary systemsAll information in conventional computers is encoded into the binary number system. That is to say that all information and numbers to be processed in the computer are represented by signals which assume one of two possible states. We are very familiar with such binary signals in everyday life. For example a switch takes one of two states — on or off. A light bulb is another example where the states are on or off. In most computer systems the binary states are represented by voltages ‘high’ (about 5 volts) and ‘low’ (about 0 volts). These states are often labelled ‘1’ and ‘0’ respectively.Binary systems also have a long history in logical discourse and argument, where the states are called ‘true’ and ‘false’. Thus the statement that the ‘earth is spherical’ would be assigned the binary state ‘true’. In fact a whole algebra based on these states, known as Boolean algebra, was developed for the analysis of logical debate during the early nineteenth century. Thus the use of binary systems in computers has its roots in a theory developed to serve this logical analysis, and this is why the circuitry used in a computer is still often referred to as ‘binary logic’.There are two main classes of such binary logic: combinatorial (sometimes also called combinational) and sequential logic. In combinatorial logic, the outcome of the system depends only
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