HP-25
The HP-25 was a programmable calculator from Hewlett-Packard ; it was the commercially very successful, inexpensive alternative to the world's first programmable pocket calculator , the HP-65 .
It was launched on the American market in 1975 at a price of US $ 195. In Germany it cost around DM 650 in 1976. It did not have a magnetic card reader and could therefore only be programmed using the keyboard. After switching off the program was lost and had to be entered again.
In total, the HP-25 had space for 49 program steps, whereby, unlike its predecessors, combined key sequences only required one step. In addition, it had eight storage registers and special scientific and statistical functions. The 161-page, four-color printed programming manual supplied with the program contained a large number of mathematical, scientific, navigational or financial program examples that were incredibly powerful for pocket calculators of the time. Jumps to labels or to insert commands were not implemented.
Like all HP pocket calculators, it used reverse Polish notation (UPN) for input and processed the numbers on a four-level stack (register names: x, y, z and t). Almost all keys were triple and could be accessed via a blue and yellow prefix key. A slide switch was used to switch between calculation mode and programming mode. The display was a twelve-digit red LED display (10 digits used). The HP-25 was the first pocket calculator to master the so-called “ technical display format ” - an exponential representation in which the exponent is always a multiple of 3, which means that it matches the SI prefixes (e.g. mega, kilo , Milli, Micro).
A year later, in 1976, brought Hewlett-Packard the largely identical HP-25C ( C ontinuous memory) out of due to the use of new low-power CMOS retained technique be turned tipptes program even after switching off. But by far not as many buyers could be addressed as with the previous model.
The HP-25 and HP-25C belong to the Woodstock series in the second generation of HP pocket calculators .
Single receipts
- ^ David G. Hicks: The Museum of HP Calculators. 1995, accessed on February 25, 2017 (English, Second Generation Handheld Calculators [1975]).
- ↑ A. Spyropoulos: 2. The Woodstock Series (1975-1979). In: HP Calculators. 2005, accessed February 25, 2017 .
Web links
- HP-25 (The Museum of HP Calculators, English)