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Hermann Schmid (computer Scientist)
A decimal computer is a computer that represents and operates on numbers and addresses in decimal format instead of binary as is common in most modern computers. Some decimal computers had a variable word length, which enabled operations on relatively large numbers. Decimal computers were common from the early machines through the 1960s and into the 1970s. Using decimal directly saved the need to convert from decimal to binary for input and output and offered a significant speed improvement over binary machines that performed these conversions using subroutines. This allowed otherwise low-end machines to offer practical performance for roles like accounting and bookkeeping, and many low- and mid-range systems of the era were decimal based. The IBM System/360 line of binary computers, announced in 1964, included instructions that perform decimal arithmetic; other lines of binary computers with decimal arithmetic instructions followed. During the 1970s, microprocessors with instr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ENIAC
ENIAC (; Electronic Numerical Integrator and Computer) was the first Computer programming, programmable, Electronics, electronic, general-purpose digital computer, completed in 1945. Other computers had some of these features, but ENIAC was the first to have them all. It was Turing-complete and able to solve "a large class of numerical problems" through reprogramming. ENIAC was designed by John Mauchly and J. Presper Eckert to calculate artillery external ballistics, firing tables for the United States Army's Ballistic Research Laboratory (which later became a part of the United States Army Research Laboratory, Army Research Laboratory). However, its first program was a study of the feasibility of the thermonuclear weapon. ENIAC was completed in 1945 and first put to work for practical purposes on December 10, 1945.* ENIAC was formally dedicated at the University of Pennsylvania on February 15, 1946, having cost $487,000 (), and called a "Giant Brain" by the press. It had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIVAC II
The UNIVAC II computer was an improvement to the UNIVAC I that the UNIVAC division of Sperry Rand first delivered in 1958. The improvements included the expansion of core memory from 2,000 to 10,000 words; UNISERVO II tape drives, which could use either the old UNIVAC I metal tapes or the new PET tapes; and some transistorized circuits (although it was still overwhelmingly a vacuum tube A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ... computer). It was fully compatible with existing UNIVAC I programs for both code and data. It weighed about . Circuit elements of entire system Above figures are approximate and do not include input-output devices. Programming and numerical system Decimal point occurs at the right of the sign digit. Arithmetic un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIVAC I
The UNIVAC I (Universal Automatic Computer I) was the first general-purpose electronic digital computer design for business application produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC. Design work was started by their company, Eckert–Mauchly Computer Corporation (EMCC), and was completed after the company had been acquired by Remington Rand (which later became part of Sperry Corporation, Sperry, now Unisys). In the years before successor models of the UNIVAC I appeared, the machine was simply known as "the UNIVAC".Johnson, L.R., "Coming to grips with Univac," IEEE Annals of the History of Computing, vol. 28, no. 2, pp. 32, 42, April–June 2006. The first UNIVAC was accepted by the United States Census Bureau on March 31, 1951, and was dedicated on June 14 that year. The fifth machine (built for the United States Atomic Energy Commission, U.S. Atomic Energy Commission) was used by CBS to predict the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alphanumeric
Alphanumericals or alphanumeric characters are any collection of number characters and letters in a certain language. Sometimes such characters may be mistaken one for the other. Merriam-Webster suggests that the term "alphanumeric" may often additionally refer to other symbols, such as punctuation and mathematical symbols. In the POSIX/C Locale (computer software), locale, there are either 36 (A–Z and 0–9, case insensitive) or 62 (A–Z, a–z and 0–9, case-sensitive) alphanumeric characters. Subsets of alphanumeric used in human interfaces When a string of mixed alphabets and numerals is presented for human interpretation, ambiguities arise. The most obvious is the similarity of the letters I, O and Q to the numbers 1 and 0. Therefore, depending on the Record locator, application, various subsets of the alphanumeric were adopted to avoid misinterpretation by humans. In passenger aircraft, aircraft seat maps and seats were designated by row number followed by column le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excess-3
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 si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Word Addressing
In computer architecture, ''word addressing'' means that addresses of memory on a computer uniquely identify words of memory. It is usually used in contrast with byte addressing, where addresses uniquely identify bytes. Almost all modern computer architectures use byte addressing, and word addressing is largely only of historical interest. A computer that uses word addressing is sometimes called a ''word machine''. Basics Consider a computer which provides 524,288 (219) bits of memory. If that memory is arranged in a byte-addressable flat address space using 8-bit bytes, then there are 65,536 (216) valid addresses, from 0 to 65,535, each denoting an independent 8 bits of memory. If instead it is arranged in a word-addressable flat address space using 32-bit words, then there are 16,384 (214) valid addresses, from 0 to 16,383, each denoting an independent 32 bits. More generally, the minimum addressable unit (MAU) is a property of a specific memory abstraction. Different a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-out-of-five Code
A two-out-of-five code is a constant-weight code that provides exactly ten possible combinations of two bits, and is thus used for representing the decimal digits using five bits. Each bit is assigned a weight, such that the set bits sum to the desired value, with an exception for zero. According to Federal Standard 1037C: * each decimal digit is represented by a binary numeral consisting of five bits of which two are of one kind, called ''ones'', and three are of the other kind, called ''zeros'', and * the usual weights assigned to the bit positions are 0-1-2-3-6. However, in this scheme, zero is encoded as binary ''01100''; strictly speaking the 0-1-2-3-6 previously claimed is just a mnemonic device. The weights give a unique encoding for most digits, but allow two encodings for 3: 0+3 or 10010 and 1+2 or 01100. The former is used to encode the digit 3, and the latter is used to represent the otherwise unrepresentable zero. The IBM 7070, IBM 7072, and IBM 7074 computers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bi-quinary Coded Decimal
Bi-quinary coded decimal is a numeral encoding scheme used in many abacuses and in some early computers, notably the Colossus. The term ''bi-quinary'' indicates that the code comprises both a two-state (''bi'') and a five-state (''quin''ary) component. The encoding resembles that used by many abacuses, with four beads indicating the five values either from 0 through 4 or from 5 through 9 and another bead indicating which of those ranges (which can alternatively be thought of as +5). Several human languages, most notably Fula and Wolof also use biquinary systems. For example, the Fula word for 6, ''jowi e go'o'', literally means ''five lusone''. Roman numerals use a symbolic, rather than positional, bi-quinary base, even though Latin is completely decimal. The Korean finger counting system Chisanbop uses a bi-quinary system, where each finger represents a one and a thumb represents a five, allowing one to count from 0 to 99 with two hands. One advantage of one bi-quina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary-coded Decimal
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIVAC Solid State 80
The UNIVAC Solid State was a magnetic drum-based solid-state computer announced by Sperry Rand in December 1958 as a response to the IBM 650. It was one of the first computers offered for sale to be (nearly) entirely solid-state, using 700 transistors, and 3000 magnetic amplifiers (FERRACTOR) for primary logic, and 20 vacuum tubes largely for power control. It came in two versions, the Solid State 80 (IBM-style 80-column cards) and the Solid State 90 (Remington-Rand 90-column cards). In addition to the "80/90" designation, there were two variants of the Solid State the SS I 80/90 and the SS II 80/90. The SS II series included two enhancements the addition of 1,280 words of core memory and support for magnetic tape drives. The SS I had only the standard 5,000-word drum memory described in this article and no tape drives. The memory drum had a regular access speed AREA and a FAST ACCESS AREA. A bank of 4,000 words of memory had one set of read/write (R/W) heads to access. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 7070
IBM 7070 is a decimal-architecture intermediate data-processing system that was introduced by IBM in 1958. It was part of the IBM 700/7000 series, and was based on discrete transistors rather than the vacuum tubes of the 1950s. It was the company's first transistorized stored-program computer. The 7070 was expected to be a "common successor to at least the 650 and the 705". The 7070 was not designed to be compatible with the 650 instruction set, as the latter had a second jump address in every instruction to allow optimal use of the drum, something unnecessary and wasteful in a computer with random-access core memory. As a result, a simulator was needed to run old programs. The 7070 was also marketed as an IBM 705 upgrade, but failed miserably due to its incompatibilities, including an inability to fully represent the 705 character set; forcing IBM to quickly introduce the IBM 7080 as a "transistorized IBM 705" that was fully compatible. The 7070 series stored data in words c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
