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HP-21
The HP-21 was a scientific calculator produced by Hewlett-Packard between 1975 and 1978. It was designed as a replacement for the HP-35, and was one of a set of three calculators, the others being the HP-22 and HP-25, which were similarly built but aimed at different markets. As with most HP calculators then and now, the HP-21 used Reverse Polish Notation, RPN entry logic, with a four-level stack. It also had a single user-accessible memory register. As was normal at the time, memory was not preserved on power-down. A physical slider switch toggled between degrees and radians modes, which was an unusual feature. It had a 12-digit LED display, which was less than the 15 digits of the HP-35. Because of these fewer digits the HP-21 (and similar calculators such as the HP-25) could display 10-digit floating point numbers but only an 8-digit mantissa with a 2-digit exponent when scientific notation was used. A shift key provided access to functions whose legends were printed on the fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-22
The HP-22 was a finance-oriented pocket calculator produced by Hewlett-Packard between 1975 and 1978. It was designed as a replacement for the short-lived HP-70, and was one of a set of three calculators, the others being the HP-21 and HP-25, which were similarly built but aimed at different markets. As with most HP calculators then and now, the HP-25 used RPN entry logic, with a four-level stack. It also had ten user-accessible memory registers. As was normal at the time, memory was not preserved on power-down. Its principal functions were (1) time value of money (TVM) calculations, where the user could enter any three of the variables and the fourth would be calculated, and (2) statistics calculations, including linear regression. Basic logarithmic and exponential functions were also provided. For TVM calculations, a physical slider switch labelled "begin" and "end" could be used to specify whether payments would be applied at the beginning or end of periods. It had a 12-dig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Calculator
A scientific calculator is an electronic calculator, either desktop or handheld, designed to perform mathematical operations. They have completely replaced slide rules and are used in both educational and professional settings. In some areas of study scientific calculators have been replaced by graphing calculators and financial calculators which have the capabilities of a scientific calculator along with the capability to graph input data. Functions When scientific calculators were originally marketed they normally had only four of five capabilities (addition, subtraction, multiplication, division and square root). Modern scientific calculators generally have many more capabilities than the original four or five function calculator, and the capabilities differ between manufacturers and models. The capabilities of a modern scientific calculator include: * scientific notation * floating-point decimal arithmetic * logarithmic functions, using both base 10 and base e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hewlett-Packard
The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components, as well as software and related services to consumers, small and medium-sized businesses ( SMBs), and large enterprises, including customers in the government, health, and education sectors. The company was founded in a one-car garage in Palo Alto by Bill Hewlett and David Packard in 1939, and initially produced a line of electronic test and measurement equipment. The HP Garage at 367 Addison Avenue is now designated an official California Historical Landmark, and is marked with a plaque calling it the "Birthplace of 'Silicon Valley'". The company won its first big contract in 1938 to provide test and measurement instruments for Walt Disney's production of the animated film ''Fantasia'', which allowed Hewlett and Packard to formally es ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-35
The HP-35 was Hewlett-Packard's first pocket calculator and the world's first ''scientific'' pocket calculator: a calculator with trigonometric and exponential functions. It was introduced in 1972. History In about 1970 HP co-founder Bill Hewlett challenged his co-workers to create a "shirt-pocket sized HP-9100". At the time, slide rules were the only practical portable devices for performing trigonometric and exponential functions, as existing pocket calculators could only perform addition, subtraction, multiplication, and division. Introduced at , like HP's first scientific calculator, the desktop 9100A, it used reverse Polish notation (RPN) rather than what came to be called "algebraic" entry. The "35" in the calculator's name came from the number of keys. The original HP-35 was available from 1972 to 1975. In 2007 HP announced the release of the "retro"-look HP 35s to commemorate the 35th anniversary of the launch of the original HP-35. It was priced at . The HP-35 wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-25
The HP-25 was a hand-held programmable scientific/engineering calculator made by Hewlett-Packard between early January 1975 and 1978. The HP-25 was introduced as a cheaper ( US$195 MSRP) alternative to the ground-breaking HP-65. To reduce cost, the HP-25 omitted the HP-65's magnetic card reader, so it could only be programmed using the keyboard. After switching off, the program was lost and had to be typed in again. The model HP-25C, introduced in 1976, addressed that shortcoming through the first use of battery-backed CMOS memory in a calculator, termed ''continuous memory'' by HP. Like all early HP calculators, the 25 used the Reverse Polish Notation (RPN) for entering calculations, working on a four-level stack (x,y,z,t). Nearly all buttons had two alternative functions, accessed by a blue and yellow prefix key. A small sliding switch was used to change between "run" and "program" mode. The HP-25 used a 10-digit red LED display and was the first calculator to introduce the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Polish Notation
Reverse Polish notation (RPN), also known as reverse Łukasiewicz notation, Polish postfix notation or simply postfix notation, is a mathematical notation in which operators ''follow'' their operands, in contrast to Polish notation (PN), in which operators ''precede'' their operands. It does not need any parentheses as long as each operator has a fixed number of operands. The description "Polish" refers to the nationality of logician Jan Łukasiewicz, who invented Polish notation in 1924. The first computer to use postfix notation, though it long remained essentially unknown outside of Germany, was Konrad Zuse's Z3 in 1941 as well as his Z4 in 1945. The reverse Polish scheme was again proposed in 1954 by Arthur Burks, Don Warren, and Jesse Wright and was independently reinvented by Friedrich L. Bauer and Edsger W. Dijkstra in the early 1960s to reduce computer memory access and use the stack to evaluate expressions. The algorithms and notation for this scheme were extended ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shift Key
The Shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row. The Shift key's name originated from the typewriter, where one had to press and hold the button to shift up the case stamp to change to capital letters; the shift key was first used in the Remington No. 2 Type-Writer of 1878; the No. 1 model was capital-only. On the US layout and similar keyboard layouts, characters that typically require the use of the shift key include the parentheses, the question mark, the exclamation point, and the colon. When the caps lock key is engaged, the shift key may be used to type lowercase letters on many operating systems, though not on macOS. Labeling The keyboard symbol for the Shift key (which is called Level 2 Select key in the international standard series ISO/IEC 9995) is given in ISO/IEC 9995-7 as symbol 1, and in ISO 700 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codename
A code name, call sign or cryptonym is a code word or name used, sometimes clandestinely, to refer to another name, word, project, or person. Code names are often used for military purposes, or in espionage. They may also be used in industrial counter-espionage to protect secret projects and the like from business rivals, or to give names to projects whose marketing name has not yet been determined. Another reason for the use of names and phrases in the military is that they transmit with a lower level of cumulative errors over a walkie-talkie or radio link than actual names. Military origins During World War I, names common to the Allies referring to nations, cities, geographical features, military units, military operations, diplomatic meetings, places, and individual persons were agreed upon, adapting pre-war naming procedures in use by the governments concerned. In the British case names were administered and controlled by the Inter Services Security Board (ISSB) staffed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
65 Notes
''PPC Journal'' was an early hobbyist computer magazine, originally targeted at users of HP's first programmable calculator, the HP-65. It originated as ''65 Notes'' and the first issue was published in 1974. It later changed names in 1978 to ''PPC Journal'' and in 1980 to ''PPC Calculator Journal''. With Volume 12 published in 1984 the magazine was renamed ''PPC Journal''. The magazine ended publication in July 1987 (Volume 14). The founder of the ''PPC'' (Personal Programming Center) and editor of the journal was Richard J. Nelson. This hobbyist group worked around the journal and was known because Nelson discovered hidden instructions on the HP-65 calculator. Later the club and the journal got maximum notoriety when several club members discovered the "synthetic instructions" of the HP-41C. Competition A similar journal since 1976 was '' 52-Notes'' for the Texas Instruments SR-52 user community. It was edited by Richard C. Vanderburgh. Both journals deliberately established ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
