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Pseudo-tetrade
In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for a sign or other indications (e.g. error or overflow). In byte-oriented systems (i.e. most modern computers), the term ''unpacked'' BCD usually implies a full byte for each digit (often including a sign), whereas ''packed'' BCD typically encodes two digits within a single byte by taking advantage of the fact that four bits are enough to represent the range 0 to 9. The precise four-bit encoding, however, may vary for technical reasons (e.g. Excess-3). The ten states representing a BCD digit are sometimes called '' tetrades'' (the nibble typically needed to hold them is also known as a tetrade) while the unused, don't care-states are named ''pseudo-tetrad(e)s'', ''pseudo-decimals'', or ''pseudo-decimal digits''. BCD's main virtue, in comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Don't Care
In digital logic, a don't-care term (abbreviated DC, historically also known as ''redundancies'', ''irrelevancies'', ''optional entries'', ''invalid combinations'', ''vacuous combinations'', ''forbidden combinations'', ''unused states'' or ''logical remainders'') for a function is an input-sequence (a series of bits) for which the function output does not matter. An input that is known never to occur is a can't-happen term. Both these types of conditions are treated the same way in logic design and may be referred to collectively as ''don't-care conditions'' for brevity. The designer of a logic circuit to implement the function need not care about such inputs, but can choose the circuit's output arbitrarily, usually such that the simplest, smallest, fastest or cheapest circuit results (circuit minimization, minimization) or the power-consumption is minimized. Don't-care terms are important to consider in minimizing logic circuit design, including graphical methods like Karnaugh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Clock
A binary clock is a clock that displays the time of day in a binary numeral system, binary format. Originally, such clocks showed ''each decimal digit'' of sexagesimal time as a binary value, but presently binary clocks also exist which display hours, minutes, and seconds as binary numbers. Most binary clocks are Digital clock, digital, although analog clock, analog varieties exist. True binary clocks also exist, which indicate the time by successively halving the day, instead of using hours, minutes, or seconds. Similar clocks, based on Gray coded binary, also exist. Binary-coded decimal clocks Most common binary clocks use six columns of LEDs to represent 0 (number), zeros and 1 (number), ones. Each column represents a single decimal digit, a format known as binary-coded decimal (BCD). The bottom row in each column represents 1 (or 20), with each row above representing higher powers of two, up to 23 (or 8). To read each individual digit in the time, the user adds the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burroughs B1700
The Burroughs B1000 Series was a series of mainframe computers, built by the Burroughs Corporation, and originally introduced in the 1970s with continued software development until 1987. The series consisted of three major generations which were the B1700, B1800, and B1900 series machines. They were also known as the Burroughs Small Systems, by contrast with the Burroughs Large Systems (B5000, B6000, B7000, B8000) and the Burroughs Medium Systems (B2000, B3000, B4000). Much of the original research for the B1700, initially codenamed the PLP ("Proper Language Processor" or "Program Language Processor"), was done at the Burroughs Pasadena plant. (Bunker, et al.), 1968. Production of the B1700s began in the mid-1970s and occurred at both the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petherick Code
Petherick ( ) may refer to: People * Alice Hext (1865–1939), née Petherick, Cornish landowner * Edward Petherick (1847–1917), Australian book collector * Horace William Petherick (1839-1919). A British artist, book illustrator, violin enthusiast and father of Rosa C. Petherick * John Petherick (1813–1882), Welsh traveller * Maurice Petherick (1894–1985), British politician * Peter Petherick (1942–2015), New Zealand cricketer * Richard Petherick (born 1986), New Zealand hockey player * Rosa C. Petherick (1871–1931), British book illustrator * Vernon Petherick (1876–1945), Australian politician Places * Hundred of Petherick, a cadastral unit in South Australia ** Petherick, South Australia, a locality * Little Petherick, a village and civil parish in Cornwall, England {{disambiguation, surname ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIVAC LARC
The UNIVAC LARC, short for the ''Livermore Advanced Research Computer'', is a mainframe computer designed to a requirement published by Edward Teller in order to run hydrodynamic simulations for nuclear weapon design. It was one of the earliest supercomputers. It used solid-state electronics. The LARC architecture supported multiprocessing with two Central processing unit, CPUs (called ''Computer''s) and an input/output (I/O) Processor (called the ''Processor''). Two LARC machines were built, the first delivered to Lawrence Livermore National Laboratory, Livermore in June 1960, and the second to the Navy's David Taylor Model Basin. Both examples had only one CPU, so no multiprocessor LARCs were ever built. Livermore decommissioned their LARC in December 1968 and the Navy's LARC was turned off in April 1969. The LARC CPUs were able to perform addition in about 4 microseconds, corresponding to about 250 kIPS speed. This made it the fastest computer in the world until 1962 when ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glixon Code
The reflected binary code (RBC), also known as reflected binary (RB) or Gray code after Frank Gray, is an ordering of the binary numeral system such that two successive values differ in only one bit (binary digit). For example, the representation of the decimal value "1" in binary would normally be "", and "2" would be "". In Gray code, these values are represented as "" and "". That way, incrementing a value from 1 to 2 requires only one bit to change, instead of two. Gray codes are widely used to prevent spurious output from electromechanical switches and to facilitate error correction in digital communications such as digital terrestrial television and some cable TV systems. The use of Gray code in these devices helps simplify logic operations and reduce errors in practice. Function Many devices indicate position by closing and opening switches. If that device uses natural binary codes, positions 3 and 4 are next to each other but all three bits of the binary representa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excess-6 Code
Offset binary, also referred to as excess-K, excess-''N'', excess-e, excess code or biased representation, is a method for signed number representation where a signed number n is represented by the bit pattern corresponding to the unsigned number n+K, K being the ''biasing value'' or ''offset''. There is no standard for offset binary, but most often the ''K'' for an ''n''-bit binary word is ''K'' = 2''n''−1 (for example, the offset for a four-digit binary number would be 23=8). This has the consequence that the minimal negative value is represented by all-zeros, the "zero" value is represented by a 1 in the most significant bit and zero in all other bits, and the maximal positive value is represented by all-ones (conveniently, this is the same as using two's complement but with the most significant bit inverted). It also has the consequence that in a logical comparison operation, one gets the same result as with a true form numerical comparison operation, whereas, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excess-3 Code
Excess-3, 3-excess or 10-excess-3 binary code (often abbreviated as XS-3, 3XS or X3), shifted binary or Stibitz code (after George Stibitz, who built a relay-based adding machine in 1937) is a self-complementary binary-coded decimal (BCD) code and numeral system. It is a biased representation. Excess-3 code was used on some older computers as well as in cash registers and hand-held portable electronic calculators of the 1970s, among other uses. Representation Biased codes are a way to represent values with a balanced number of positive and negative numbers using a pre-specified number ''N'' as a biasing value. Biased codes (and Gray codes) are non-weighted codes. In excess-3 code, numbers are represented as decimal digits, and each digit is represented by four bits as the digit value plus 3 (the "excess" amount): * The smallest binary number represents the smallest value (). * The greatest binary number represents the largest value (). To encode a number such as 127, one s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aiken Code
The Aiken code (also known as 2421 code) is a complementary binary-coded decimal (BCD) code. A group of four bits is assigned to the decimal digits from 0 to 9 according to the following table. The code was developed by Howard Hathaway Aiken and is still used today in digital clocks, pocket calculators and similar devices. The Aiken code differs from the standard 8421 BCD code in that the Aiken code does not weight the fourth digit as 8 as with the standard BCD code but with 2. The following weighting is obtained for the Aiken code: 2-4-2-1. One might think that double codes are possible for a number, for example 1011 and 0101 could represent 5. However, here one makes sure that the digits 0 to 4 are mirror image complementary to the numbers 5 to 9. See also * Excess-3 code * Gray code * O'Brien code type I References Further reading * {{cite journal , title=Coded Decimal Number Systems for Digital Computers , author-first=Garland S. , author-last=White , journal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-off Error
In computing, a roundoff error, also called rounding error, is the difference between the result produced by a given algorithm using exact arithmetic and the result produced by the same algorithm using finite-precision, rounded arithmetic. Rounding errors are due to inexactness in the representation of real numbers and the arithmetic operations done with them. This is a form of quantization error. When using approximation equations or algorithms, especially when using finitely many digits to represent real numbers (which in theory have infinitely many digits), one of the goals of numerical analysis is to estimate computation errors. Computation errors, also called numerical errors, include both truncation errors and roundoff errors. When a sequence of calculations with an input involving any roundoff error are made, errors may accumulate, sometimes dominating the calculation. In ill-conditioned problems, significant error may accumulate. In short, there are two major facets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floating-point
In computing, floating-point arithmetic (FP) is arithmetic on subsets of real numbers formed by a ''significand'' (a Sign (mathematics), signed sequence of a fixed number of digits in some Radix, base) multiplied by an integer power of that base. Numbers of this form are called floating-point numbers. For example, the number 2469/200 is a floating-point number in base ten with five digits: 2469/200 = 12.345 = \! \underbrace_\text \! \times \! \underbrace_\text\!\!\!\!\!\!\!\overbrace^ However, 7716/625 = 12.3456 is not a floating-point number in base ten with five digits—it needs six digits. The nearest floating-point number with only five digits is 12.346. And 1/3 = 0.3333… is not a floating-point number in base ten with any finite number of digits. In practice, most floating-point systems use Binary number, base two, though base ten (decimal floating point) is also common. Floating-point arithmetic operations, such as addition and division, approximate the correspond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
