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The table shown on the right can be used in a two-sample t-test to estimate the sample sizes of an experimental group and a control group that are of equal size, that is, the total number of individuals in the trial is twice that of the number given, and the desired significance level is 0.05. [4]
Was the first scientific calculator to fly in space in 1973. [5] HP-35 calculators were carried on the Skylab 3 and Skylab 4 flights, between July 1973 and February 1974. [6] Is the first pocket calculator with a numeric range that covered 200 decades (more precise 199, ±10 ±99). [5]
The Curta was conceived by Curt Herzstark in the 1930s in Vienna, Austria.By 1938, he had filed a key patent, covering his complemented stepped drum. [3] [4] This single drum replaced the multiple drums, typically around 10 or so, of contemporary calculators, and it enabled not only addition, but subtraction through nines complement math, essentially subtracting by adding.
The range was further extended by the inclusion of the Series J ten-key machines which provided a single finger calculation facility, and the Class 5 (later called Series C) key-driven calculators in both manual and electrical assisted comptometers. In the late 1960s, the Burroughs sponsored "nixi-tube" provided an electronic display calculator ...
By 1970, a calculator could be made using just a few chips of low power consumption, allowing portable models powered from rechargeable batteries. The first handheld calculator was a 1967 prototype called Cal Tech, whose development was led by Jack Kilby at Texas Instruments in a research project to produce a portable calculator. It could add ...
Calculators supporting such programming were Turing-complete if they supported both conditional statements and indirect addressing of memory. Notable examples of Turing complete calculators were Casio FX-602P series, the HP-41 and the TI-59. Keystroke programming is still used in mid-range calculators like the HP 35s and HP-12C.
The pocket-sized Hewlett-Packard HP-35 scientific calculator was the first handheld device of its type, but it cost US$395 in 1972. This was justifiable for some engineering professionals, but too expensive for most students. Around 1974, lower-cost handheld electronic scientific calculators started to make slide rules largely obsolete.
The Hewlett-Packard 9100A (HP 9100A) is an early programmable calculator [3] (or computer), first appearing in 1968. HP called it a desktop calculator because, as Bill Hewlett said, "If we had called it a computer, it would have been rejected by our customers' computer gurus because it didn't look like an IBM. We therefore decided to call it a ...