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Adder–subtractor
In digital circuits, an adder–subtractor is a circuit that is capable of adding or subtracting numbers (in particular, binary). Below is a circuit that adds ''or'' subtracts depending on a control signal. It is also possible to construct a circuit that performs both addition and subtraction at the same time. Construction Having an ''n''-bit adder for ''A'' and ''B'', then . Then, assume the numbers are in two's complement. Then to perform , two's complement theory says to invert each bit of ''A'' with a NOT gate then add one. This yields , which is easy to do with a slightly modified adder. By preceding each ''A'' input bit on the adder with a 2-to-1 multiplexer where: * Input 0 (''I''0) is ''A'' * Input 1 (''I''1) is that has control input ''D'' that is also connected to the initial carry, then the modified adder performs * addition when , or * subtraction when . This works because when the ''A'' input to the adder is really and the carry in is 1. Adding ''B'' to an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adder (electronics)
An adder, or summer, is a digital circuit that performs addition of numbers. In many computers and other kinds of microprocessor, processors adders are used in the arithmetic logic units (ALUs). They are also used in other parts of the processor, where they are used to calculate address space, addresses, database index, table indices, increment and decrement operators and similar operations. Although adders can be constructed for many number representations, such as binary-coded decimal or excess-3, the most common adders operate on binary numbers. In cases where two's complement or ones' complement is being used to represent negative numbers, it is trivial to modify an adder into an adder–subtractor. Other signed number representations require more logic around the basic adder. Binary adders Half adder The half adder adds two single binary digits ''A'' and ''B''. It has two outputs, sum (''S'') and carry (''C''). The carry signal represents an Integer overflow, overflow int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adder (electronics)
An adder, or summer, is a digital circuit that performs addition of numbers. In many computers and other kinds of microprocessor, processors adders are used in the arithmetic logic units (ALUs). They are also used in other parts of the processor, where they are used to calculate address space, addresses, database index, table indices, increment and decrement operators and similar operations. Although adders can be constructed for many number representations, such as binary-coded decimal or excess-3, the most common adders operate on binary numbers. In cases where two's complement or ones' complement is being used to represent negative numbers, it is trivial to modify an adder into an adder–subtractor. Other signed number representations require more logic around the basic adder. Binary adders Half adder The half adder adds two single binary digits ''A'' and ''B''. It has two outputs, sum (''S'') and carry (''C''). The carry signal represents an Integer overflow, overflow int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Circuit
In theoretical computer science, a circuit is a model of computation in which input values proceed through a sequence of gates, each of which computes a function. Circuits of this kind provide a generalization of Boolean circuits and a mathematical model for digital logic circuits. Circuits are defined by the gates they contain and the values the gates can produce. For example, the values in a Boolean circuit are boolean values, and the circuit includes conjunction, disjunction, and negation gates. The values in an integer circuit are sets of integers and the gates compute set union, set intersection, and set complement, as well as the arithmetic operations addition and multiplication. Formal definition A circuit is a triple (M, L, G), where * M is a set of values, * L is a set of gate labels, each of which is a function from M^ to M for some non-negative integer i (where i represents the number of inputs to the gate), and * G is a labelled directed acyclic graph with labels fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Arithmetic
A binary number is a number expressed in the base-2 numeral system or binary numeral system, a method of mathematical expression which uses only two symbols: typically "0" (zero) and "1" (one). The base-2 numeral system is a positional notation with a radix of 2. Each digit is referred to as a bit, or binary digit. Because of its straightforward implementation in digital electronic circuitry using logic gates, the binary system is used by almost all modern computers and computer-based devices, as a preferred system of use, over various other human techniques of communication, because of the simplicity of the language and the noise immunity in physical implementation. History The modern binary number system was studied in Europe in the 16th and 17th centuries by Thomas Harriot, Juan Caramuel y Lobkowitz, and Gottfried Leibniz. However, systems related to binary numbers have appeared earlier in multiple cultures including ancient Egypt, China, and India. Leibniz was specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications Equipment
Telecommunications equipment (also telecoms equipment or communications equipment) are hardware which are used for the purposes of telecommunications. Since the 1990s the boundary between telecoms equipment and IT hardware has become blurred as a result of the growth of the internet and its increasing role in the transfer of telecoms data. Types Telecommunications equipment can be broadly broken down into the following categories: *Public switching equipment **Analogue switches **Digital switches ***Voice over IP switches ***Virtual reality (VR) *Transmission equipment **Transmission lines ***Optical fiber ***Local loops **Base transceiver stations **Free-space optical communication ***Laser communication in space **Multiplexers **Communications satellites *Customer premises equipment (CPE) ** Customer office terminal **Private switches **Local area networks (LANs) **Modems **Mobile phones ** Landline telephones **Answering machines **Teleprinters **Fax machines **Pagers ** Router ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subtractor
In electronics, a subtractor – a digital circuit that performs subtraction of numbers – can be designed using the same approach as that of an adder. The binary subtraction process is summarized below. As with an adder, in the general case of calculations on multi-bit numbers, three bits are involved in performing the subtraction for each bit of the difference: the minuend (X_), subtrahend (Y_), and a borrow in from the previous (less significant) bit order position (B_). The outputs are the difference bit (D_) and borrow bit B_. The subtractor is best understood by considering that the subtrahend and both borrow bits have negative weights, whereas the X and D bits are positive. The operation performed by the subtractor is to rewrite X_-Y_-B_ (which can take the values -2, -1, 0, or 1) as the sum -2B_+D_. : D_ = X_ \oplus Y_ \oplus B_ : B_ = X_ < (Y_ + B_) Subtractors are usually implemented within a binary adder for only a small cost when using the standard |
Adding Machine
An adding machine is a class of mechanical calculator, usually specialized for bookkeeping calculations. In the United States, the earliest adding machines were usually built to read in dollars and cents. Adding machines were ubiquitous office equipment until they were phased out in favor of calculators in the 1970s and by personal computers beginning in about 1985. The older adding machines were rarely seen in American office settings by the year 2000. Blaise Pascal and Wilhelm Schickard were the two original inventors of the mechanical calculator in 1642. For Pascal, this was an adding machine that could perform additions and subtractions directly and multiplication and divisions by repetitions, while Schickard's machine, invented several decades earlier, was less functionally efficient but was supported by a mechanised form of multiplication tables. These two were followed by a series of inventors and inventions leading to those of Thomas de Colmar, who launched the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carry-lookahead Adder
A carry-lookahead adder (CLA) or fast adder is a type of electronics adder used in digital logic. A carry-lookahead adder improves speed by reducing the amount of time required to determine carry bits. It can be contrasted with the simpler, but usually slower, ripple-carry adder (RCA), for which the carry bit is calculated alongside the sum bit, and each stage must wait until the previous carry bit has been calculated to begin calculating its own sum bit and carry bit. The carry-lookahead adder calculates one or more carry bits before the sum, which reduces the wait time to calculate the result of the larger-value bits of the adder. Already in the mid 1800s, Charles Babbage recognized the performance penalty imposed by the ripple-carry used in his Difference Engine, and subsequently designed mechanisms for ''anticipating carriage'' for his (never-built) Analytical Engine. Konrad Zuse is thought to have implemented the first carry-lookahead adder in his 1930s binary mechanical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Op Code
In computing, an opcode (abbreviated from operation code, also known as instruction machine code, instruction code, instruction syllable, instruction parcel or opstring) is the portion of a machine language instruction that specifies the operation to be performed. Beside the opcode itself, most instructions also specify the data they will process, in the form of operands. In addition to opcodes used in the instruction set architectures of various CPUs, which are hardware devices, they can also be used in abstract computing machines as part of their byte code specifications. Overview Specifications and format of the opcodes are laid out in the instruction set architecture ( ISA) of the processor in question, which may be a general CPU or a more specialized processing unit. Opcodes for a given instruction set can be described through the use of an opcode table detailing all possible opcodes. Apart from the opcode itself, an instruction normally also has one or more specifiers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arithmetic Logic Unit
In computing, an arithmetic logic unit (ALU) is a Combinational logic, combinational digital circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on floating point numbers. It is a fundamental building block of many types of computing circuits, including the central processing unit (CPU) of computers, FPUs, and graphics processing units (GPUs). The inputs to an ALU are the data to be operated on, called operands, and a code indicating the operation to be performed; the ALU's output is the result of the performed operation. In many designs, the ALU also has status inputs or outputs, or both, which convey information about a previous operation or the current operation, respectively, between the ALU and external status registers. Signals An ALU has a variety of input and output net (electronics), nets, which are the electrical conductors used to convey Digital signal (electronics), digi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Unit
The control unit (CU) is a component of a computer's central processing unit (CPU) that directs the operation of the processor. A CU typically uses a binary decoder to convert coded instructions into timing and control signals that direct the operation of the other units (memory, arithmetic logic unit and input and output devices, etc.). Most computer resources are managed by the CU. It directs the flow of data between the CPU and the other devices. John von Neumann included the control unit as part of the von Neumann architecture. In modern computer designs, the control unit is typically an internal part of the CPU with its overall role and operation unchanged since its introduction. Multicycle control units The simplest computers use a multicycle microarchitecture. These were the earliest designs. They are still popular in the very smallest computers, such as the embedded systems that operate machinery. In a multicycle computer, the control unit often steps through the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
