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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] |
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 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 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 HP 9100 desktop scientific calculator. This was a full-featured calculator that included not only standard "adding machine" functions but also powerful capabilities ... [...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 trademark ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Random-access Memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory, in contrast with other direct-access data storage media (such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory), where the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement. RAM contains multiplexing and demultiplexing circuitry, to connect the data lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, and RAM devices often have multiple data lines and are said to be "8-bit" or "16-bit", etc. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-29C
The HP-19C and HP-29C were scientific/engineering pocket calculators made by Hewlett-Packard between 1977 and 1979. They were the most advanced and last models of the "20" family (compare HP-25) and included '' Continuous Memory'' (battery-backed CMOS memory) as a standard feature. The HP-19C included a small thermal printer, one of the very few hand-held scientific calculators to offer such a feature (HP-91, HP-92 and HP-97 were desktop units and later models like the HP-41C only supported external printers). Due to the printer's power requirements, the 19C used a battery pack of four AA-sized NiCd cells, adding to the weight of the calculator and printer mechanism. All other capabilities were the same in both models – RPN expression logic, 98 program memory locations, statistical functions, and 30 registers. Users could develop software for the HP-29C/19C, such as a prime number generator. The calculators expanded the HP-25's program capabilities by adding su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-19C
The HP-19C and HP-29C were scientific/engineering pocket calculators made by Hewlett-Packard between 1977 and 1979. They were the most advanced and last models of the "20" family (compare HP-25) and included '' Continuous Memory'' (battery-backed CMOS memory) as a standard feature. The HP-19C included a small thermal printer, one of the very few hand-held scientific calculators to offer such a feature (HP-91, HP-92 and HP-97 were desktop units and later models like the HP-41C only supported external printers). Due to the printer's power requirements, the 19C used a battery pack of four AA-sized NiCd cells, adding to the weight of the calculator and printer mechanism. All other capabilities were the same in both models – RPN expression logic, 98 program memory locations, statistical functions, and 30 registers. Users could develop software for the HP-29C/19C, such as a prime number generator. The calculators expanded the HP-25's program capabilities by adding su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TI Constant Memory
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" (AO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-34C
The HP-34C continuous memory calculator was an advanced scientific programmable calculator of the HP 30 series. It was produced between 1979 (cost US$150) and 1983 (cost US$100). Features Root-finding and integration Significant to the HP-34C calculator was the capability for integration and root-finding (a first for any pocket calculator). Integration and root-finding worked by having the user input a formula as a program. Multiple roots are found using the technique of first finding a root x=x_0, then dividing the equation by (x-x_0), thus driving the solution of the equation away from the root at that point. This technique for multiple root-finding is referred to as "deflation". The user would usually programmatically recall the root value from a storage register to improve its precision. Programming The common method of converting registers to program memory allowed the calculator a maximum of 210 program steps. Programming features such as indirect jumps provided sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP Voyager Series
The Hewlett-Packard Voyager series of calculators were introduced by Hewlett-Packard in 1981. All members of this series are programmable, use Reverse Polish Notation, and feature continuous memory. Nearly identical in appearance, each model provided different capabilities and was aimed at different user markets. Models The HP calculators Voyager series consisted of five models, some of which were manufactured in several variants (with years of production): *HP-10C – basic scientific calculator (1982–1984). *HP-11C – mid-range scientific calculator (1981–1989). *HP-12C – business/financial calculator (1981–present). *HP-15C – advanced scientific calculator (1982–1989, 2011). *HP-16C – computer programmer's calculator (1982–1989). HP-10C The HP-10C is the last and lowest-featured calculator in this line, even though its number would suggest an earlier origin. The 10C was a basic scientific programmable calculator. While a useful gener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-10C
The Hewlett-Packard Voyager series of calculators were introduced by Hewlett-Packard in 1981. All members of this series are programmable, use Reverse Polish Notation, and feature continuous memory. Nearly identical in appearance, each model provided different capabilities and was aimed at different user markets. Models The HP calculators Voyager series consisted of five models, some of which were manufactured in several variants (with years of production): * HP-10C – basic scientific calculator (1982–1984). *HP-11C – mid-range scientific calculator (1981–1989). *HP-12C – business/financial calculator (1981–present). *HP-15C – advanced scientific calculator (1982–1989, 2011). *HP-16C – computer programmer's calculator (1982–1989). HP-10C The HP-10C is the last and lowest-featured calculator in this line, even though its number would suggest an earlier origin. The 10C was a basic scientific programmable calculator. While a useful ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HP-11C
The Hewlett-Packard Voyager series of calculators were introduced by Hewlett-Packard in 1981. All members of this series are programmable, use Reverse Polish Notation, and feature continuous memory. Nearly identical in appearance, each model provided different capabilities and was aimed at different user markets. Models The HP calculators Voyager series consisted of five models, some of which were manufactured in several variants (with years of production): * HP-10C – basic scientific calculator (1982–1984). * HP-11C – mid-range scientific calculator (1981–1989). *HP-12C – business/financial calculator (1981–present). *HP-15C – advanced scientific calculator (1982–1989, 2011). *HP-16C – computer programmer's calculator (1982–1989). HP-10C The HP-10C is the last and lowest-featured calculator in this line, even though its number would suggest an earlier origin. The 10C was a basic scientific programmable calculator. While a useful g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
