HP-35

With their first pocket calculators HP -35, Hewlett -Packard introduced in 1972 the world's first scientific pocket calculator with trigonometric, logarithmic and Exponentialrechnungs features on the market. He was the first of a long series of mostly programmable calculators of the company.

On 12 July 2007 the successor HP 35s was Hewlett- Packard, the 35 -year anniversary, put on the market.

History of development

Prior to the HP -35 slide rule and table books were the only practical tool for computing trigonometric and exponential calculation functions. The existing electronic calculator that time dominated only the four basic arithmetic operations.

Although contemporary market surveys had shown no need for a calculator, although HP co-founder Bill Hewlett started the development of a "HP- 9100A pocket-size" and the marketing forecasts proved soon to be false: Already in the first months exceeded the number of orders HPs expectations from the total demand of the market.

For the launch of the HP -35 in the United States, the sale price was 395 U.S. dollars. In slightly different design variants of this model was produced from 1972 to 1975.

Technology

Like the Reverse Polish Notation (RPN ) has been selected to enter the HP - 35 for the desktop computer HP- 9100. Therefore, the HP -35 does not provide, as now usually the case, a button with an equal sign at the end of a calculation, but a enter key to separate the input successively entered the computing operands. The computational procedure is started by pressing the desired rake operation button immediately after entering the second operand. The stack ( stack ) has been extended on four levels, the top level (T) is, however, shared for trigonometric functions.

The computer used the conventional floating-point display for so representable numbers, but switched for larger or smaller number of values ​​that were no longer represented in floating point format, automatically in scientific exponential order. The 15 - digit LED display could be a 10-digit mantissa plus a 2-digit decimal exponent, each with a sign. In a multiplex method was each single LED segment, instead of - as hitherto usual - each complete LED seven-segment digit, the display successively brought to light, as investigations at HP had shown that in this way, with the same power consumption, a brighter overall impression was written for the human eye.

For power supply a serving of three NiCd cells in AA cell size of existing battery pack and an external Steckernetz-/ladegerät, which can also be used without an inserted battery pack.

The internal calculation methods use 14-digit BCD numbers that are processed by a 56-bit floating-point representation of the 1- bit - serially operating chipset.

Successor

The HP -35, produced from 1972 to 1975, was the beginning of a family of related calculator with a very similar case design:

  • The HP -80, HP's second calculator, produced from 1973 to 1978 was specializing in financial functions. As a cheaper alternative was from 1974 to 1975, the reduced functionality in HP -70 offered.
  • The HP -45, produced from 1973 to 1976, was ( with still 35 keys) compared to the HP -35 extended by inclusion of a second-function key α to include additional functions, including the ability to set the display format manually instead of just automatically. As an undocumented feature the firmware contained a stopwatch, but due to a lack of quartz stabilization of the clock frequency quite inaccurate worked.
  • The HP -65, produced from 1974 to 1977, was the world's first programmable calculator, and with that came the first time Bill Hewlett's requirement of a "HP- 9100 pocket-size" close. The HP -65 possessed remarkably, in the form of an integrated magnetic card reader already has an external storage medium for programs containing up to 100 program steps, offered a program sequencer with conditional branches and loops and flag control, and umdefinierbare by the user software keys A through E. this model had still only 35 keys, but with up to four-fold multiple occupancy.
  • The HP -55, produced from 1975 to 1977, was a cheaper sister model of the HP -65, without magnetic card reader and reduced program memory. The built- in HP -55 crystal oscillator allowed the officially documented use of the applied already in the HP -45 stopwatch function.
  • The HP -67, produced from 1976 to 1982 with the new technology of the so-called Twenties series ( HP -21, HP -22, HP- 25, HP- 29C ), offered more program and data memory, and various functional improvements over the HP -65.
  • Established in 2007, introduced to the market successor HP 35s for 35-year anniversary is a programmable scientific calculator, which can be operated either algebraically or in reverse Polish notation. It has an equation solver, numerical integration, and 32 KB of memory. Manufacturer is the company Kinpo.

Trivia

  • Originally, the new device only The Calculator should be called, but Bill Hewlett beat HP -35 before because of the number of 35 keys.
  • The HP -35 was exactly 5.8 inches long and 3.2 inches American wide, just like William Hewlett's shirt pocket, hence the name calculator.
  • Due to the energy-hungry LED filed a battery charge with the then available low battery capacity (about 450 mAh ) is only about three hours. But in order to wear the Power button to avoid excessively frequent switching, was simply saved in computing breaks by pressing the decimal point key stream; because that shone only a single decimal point of the LED display.
  • The complete implementation of arithmetic, logarithmic and trigonometric functions of the HP -35 consisted of 767 cleverly programmed command started with a command word length of ten bits (= 7670 bits). The three ROM chips each with 256 10 -bit words of the bit-serial working computer are provided with only ten pins round metal housing in the middle of the motherboard; Today, an unusual design for ICs.
  • The introduction of the HP -35, and soon also similar powerful scientific calculator from Texas Instruments, quickly led to the release of the slide rule as a status symbol among science and engineering students through professional electronic calculator. Courses on the use of slide rules disappeared from the curriculum.
  • The computer engineer Steve Wozniak worked in the development team of the HP -35, before a few years later with his friend Steve Jobs founded the computer company Apple.
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