HP-28 series
Encyclopedia
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
from 1986 to 1992.
The HP-28 was the first calculator capable of solving equations symbolically.
They were replaced by the HP-48 series
HP-48 series
The HP-48 is a series of graphing calculators using Reverse Polish notation and the RPL programming language, produced by Hewlett-Packard from 1990 until 2003. The series include the HP-48S, HP-48SX, HP-48G, HP-48GX, and HP-48G+, the G models being expanded and improved versions of the S models...
of calculators, which grew from the menu-driven RPL programming language
RPL programming language
The RPL programming language is a handheld calculator system and application programming language used on Hewlett-Packard's engineering graphing RPN calculators of the HP-28, HP-48, HP-49 and HP-50 series, but it is also usable on non-RPN calculators, such as the HP-39...
interface first introduced in the HP-28 series.
The HP-28 calculators shared a flip-open (book style) case. On the left side of the flip, there is an alphabetic keyboard (in alphabetic order). On the right was a typical scientific keyboard layout. The display was a 137x32 LCD matrix, usually displaying four lines of information (3 stack/command lines, plus one softkey label line).
Two models were produced, the HP-28C came first in 1987 with two kilobytes of usable RAM, and was the first calculator with a Computer Algebra System
Computer algebra system
A computer algebra system is a software program that facilitates symbolic mathematics. The core functionality of a CAS is manipulation of mathematical expressions in symbolic form.-Symbolic manipulations:...
. A year later, the more common HP-28S was released with 32k of RAM and a directory system for filing variables, functions, and programs. The HP-28C used a single Saturn
Saturn (microprocessor)
The Saturn family of microprocessors was developed by Hewlett-Packard in the 1980s for programmable scientific calculators/microcomputers. The original Saturn chipset was first used in the HP-71B hand-held BASIC computer, introduced in 1984. Later models of the family powered the popular HP-48...
processor at 640 kHz whereas the HP-28S used a custom chip containing an improved Saturn processor core at 1 MHz. The HP-48S, the replacement for the 28, used the HP-28S CPU core at 2 MHz.
The HP-28C was the last HP model introduced with the suffix "C" in its model designation – a practice which HP had started with the HP-25C back in 1976. The "C" had distinguished those models as having continuous memory. However by 1988 that capability had become so common on calculators that it was no longer a feature of distinction, as it was an assumed characteristic of all serious scientific and business calculators. So beginning with the HP-28S, HP-17B, HP-19B, and HP-27S, the feature suffix "C" was replaced with a class suffix which was more meaningful in the market: "S" for Scientific, "B" for Business, and later (in 1993) "G" for Graphic.
Among the drawbacks of the HP-28 was the lack of a computer interface. This meant that stored information could only be entered through the keypad and not backed up.
The plastic of the case around the battery cover is prone to breaking, surviving examples of this calculator frequently have tape over the cover to hold it in place (including the image attached to this article).
See also
- Graphing CalculatorGraphing CalculatorGraphing Calculator may refer to:* Graphing calculators, calculators that are able to display and/or analyze mathematical function graphs.* NuCalc, a computer software program able to perform many graphing calculator functions....
- HP calculatorsHP calculatorsHP calculators are various calculators manufactured by the Hewlett-Packard company over the years.- 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...
- Comparison of HP graphing calculatorsComparison of HP graphing calculatorsA graphing calculator is a class of hand-held calculator that is capable of plotting graphs and solving complex functions. While there are several companies that manufacture models of graphing calculators, HP is a major manufacturer....
- HP-48 -- successor of the HP-28 series
External links
- HP-28 at the HP Calculator Museum
- A musical chords playing program
- HP-28S pictures on MyCalcDB (database about 70's and 80's pocket calculators)
- HP Calculators - Replacement Batteries
- Paul CourbisPaul CourbisPaul Courbis , is a French programmer, mostly known for reverse engineering the HP-28 and then the HP-48 series of calculator, and writing multiple articles and books disclosing his findings...
and Sébastien Lalande (1988), French book about ML programming, hardware upgrade and more (PDF files). - HP-28 from Tony's Taschenrechner-Sammlung Calculator-Collection
- The HP28 WWW Archive
- ND1 -- A modern re-implementation for iPhone and iPod touch