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HP-25C
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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP Continuous Memory
The term continuous memory was coined by Hewlett-Packard (HP) to describe a unique feature of certain HP calculators whereby the calculator could internally sustain most, or in later models - all, of the contents of user memory (via battery-backed CMOS memory). Since its introduction on the HP-25C, this feature slowly evolved by model to eventually mean maintaining the contents of nearly all calculator memory, including system and scratch RAM, options, settings, flags, and other calculator state information. Before the introduction of the HP-25C in 1976, all calculator random-access memory (RAM) was volatile, i.e. its contents (esp. user data in storage registers and any user programs) were cleared when the calculator was turned off. Three early models with this improved, continuous memory - the HP-25C, HP-29C, and HP-19C - actually had the words "'' Continuous Memory ''" printed in conspicuous, white script on the bottom margin of their faceplates. The "C" in the model design ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP Calculators
HP calculators are various calculators manufactured by the Hewlett-Packard company over the years. Their desktop models included the HP 9800 series, while their handheld models started with the HP-35. Their focus has been on high-end scientific, engineering and complex financial uses. History In the 1960s, Hewlett-Packard was becoming a diversified electronics company with product lines in electronic Measuring instrument, test equipment, scientific instrumentation, and medical electronics, and was just beginning its entry into computers. The corporation recognized two opportunities: it might be possible to automate the instrumentation that HP was producing, and HP's customer base were likely to buy a product that could replace the slide rules and adding machines that were being used for computation. With this in mind, HP built the Hewlett-Packard 9100A, HP 9100 desktop scientific calculator. This was a full-featured calculator that included not only standard "adding machine" f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pocket Calculators
An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics. The first solid-state electronic calculator was created in the early 1960s. Pocket-sized devices became available in the 1970s, especially after the Intel 4004, the first microprocessor, was developed by Intel for the Japanese calculator company Busicom. Modern electronic calculators vary from cheap, give-away, credit-card-sized models to sturdy desktop models with built-in printers. They became popular in the mid-1970s as the incorporation of integrated circuits reduced their size and cost. By the end of that decade, prices had dropped to the point where a basic calculator was affordable to most and they became common in schools. Computer operating systems as far back as early Unix have included interactive calculator programs such as dc and hoc, and interactive BASIC could be used to do calculations on most 1970s and 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programmable Calculator
Programmable calculators are calculators that can automatically carry out a sequence of operations under control of a stored program. Most are Turing complete, and, as such, are theoretically general-purpose computers. However, their user interfaces and programming environments are specifically tailored to make performing small-scale numerical computations convenient, rather than general-purpose use. The first programmable calculators such as the IBM CPC used punched cards or other media for program storage. Hand-held electronic calculators store programs on magnetic strips, removable read-only memory cartridges, flash memory, or in battery-backed read/write memory. Since the early 1990s, most of these flexible handheld units belong to the class of graphing calculators. Before the mass-manufacture of inexpensive dot-matrix LCDs, however, programmable calculators usually featured a one-line numeric or alphanumeric display. The Big Four manufacturers of programmable calcula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering Notation
Engineering notation or engineering form (also technical notation) is a version of scientific notation in which the exponent of ten must be divisible by three (i.e., they are powers of a thousand, but written as, for example, 106 instead of 10002). As an alternative to writing powers of 10, SI prefixes can be used, which also usually provide steps of a factor of a thousand. On most calculators, engineering notation is called "ENG" mode. History An early implementation of engineering notation in form of range selection and number display with SI prefixes was introduced in the computerized HP 5360A frequency counter by Hewlett-Packard in 1969. Based on an idea by Peter D. Dickinson the first calculator to support engineering notation displaying the power-of-ten exponent values was the HP-25 in 1975. It was implemented as a dedicated display mode in addition to scientific notation. In 1975, Commodore introduced a number of scientific calculators (like the SR4148/SR4148R and ... [...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 Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fully Merged Keycodes
Fully () is a municipality in the district of Martigny in the canton of Valais in Switzerland. History Fully is first mentioned in the 11th Century as ''Fuliacum''. Geography Fully has an area, , of . Of this area, 30.5% is used for agricultural purposes, while 27.7% is forested. Of the rest of the land, 5.7% is settled (buildings or roads) and 36.2% is unproductive land. It is on the right bank of the river Rhône and is well known for its wines. Fully is just the administrative name of a group of several villages of Vers-l'Eglise (sometimes called Fully), Branson, Châtaignier and Randonnaz along with a number of hamlets. The natural reserve of Les Follatères (shared between Fully and Dorénaz), located on the south facing slopes above the Rhône elbow, has a variety of animal and plant species normally uncommon in Switzerland. Fully-suisse.jpg, Fully at the foot of the Grand Chavalard Colourful lizard - panoramio.jpg, Green lizard Cactuses.jpg, Cactuses (Opunti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TI-57
The TI-57 was a programmable calculator made by Texas Instruments between 1977 and 1982. There were three machines by this name made by TI, the first was the TI-57 with LED display released in September 1977 along the more powerful TI-58 and TI-59. It had 50 program steps and eight memory registers. Two later versions named TI-57 LCD and TI-57 LCD-II have a LCD display, but were less powerful (ran much slower) and had much less memory: 48 bytes to be allocated between program 'steps' and storage registers. The TI-57 lacked non-volatile memory, so any programs entered were lost when the calculator was switched off or the battery ran out. The LED display version of the TI-57 had a rechargeable Nickel-Cadmium battery pack BP7 which contains two AA size batteries and electronics to raise the voltage to the 9V required by the calculator. A popular modification is to power it from a 9V battery and use the battery cover of a LED TI-30 or a part of the dismantled battery pack. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TI-58
The TI-59 is an early programmable calculator, that was manufactured by Texas Instruments from 1977. It is the successor to the TI SR-52, quadrupling the number of "program steps" of storage, and adding "ROM Program Modules" (an insertable ROM chip, capable of holding 5000 program steps). Just like the SR-52, it has a magnetic card reader for external storage. One quarter of the memory is stored on each side of one card. The TI-58 (May 1977), and later TI-58C (1979), are cut-down versions of the TI-59, lacking the magnetic card reader and having half the memory, but otherwise identical. Although the TI-58C uses a different chip than the TI-58, the technical data remain identical. The "C" in a TI (or Hewlett-Packard) model name indicates that the calculator has a ''constant'' memory (or continuous memory, respectively) allowing retention of programs and data when turned off. These calculators use a parenthesized infix calculation system called " Algebraic Operating System" (AOS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calculator Input Methods
There are various ways in which calculators interpret keystrokes. These can be categorized into two main types: * On a single-step or immediate-execution calculator, the user presses a key for each operation, calculating all the intermediate results, before the final value is shown. * On an expression or formula calculator, one types in an expression and then presses a key, such as "=" or "Enter", to evaluate the expression. There are various systems for typing in an expression, as described below. Immediate execution The immediate execution mode of operation (also known as single-step, algebraic entry system (AES) or chain calculation mode) is commonly employed on most general-purpose calculators. In most simple four-function calculators, such as the Windows calculator in Standard mode and those included with most early operating systems, each binary operation is executed as soon as the next operator is pressed, and therefore the order of operations in a mathematical expression ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stack (abstract Data Type)
In computer science, a stack is an abstract data type that serves as a collection of elements, with two main operations: * Push, which adds an element to the collection, and * Pop, which removes the most recently added element that was not yet removed. Additionally, a peek operation can, without modifying the stack, return the value of the last element added. Calling this structure a ''stack'' is by analogy to a set of physical items stacked one atop another, such as a stack of plates. The order in which an element added to or removed from a stack is described as last in, first out, referred to by the acronym LIFO. As with a stack of physical objects, this structure makes it easy to take an item off the top of the stack, but accessing a datum deeper in the stack may require taking off multiple other items first. Considered as a linear data structure, or more abstractly a sequential collection, the push and pop operations occur only at one end of the structure, referred ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips (including CMOS BIOS), and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors ( CMOS sensors), data converters, RF circuits ( RF CMOS), and highly integrated transceivers for many types of communication. The CMOS process was originally conceived by Frank Wanlass at Fairchild Semiconductor and presented by Wanlass and Chih-Tang Sah at the International Solid-State Circuits Conference in 1963. Wanlass later filed US patent 3,356,858 for CMOS circuitry and it was granted in 1967. commercialized the technology with the trademar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
