The HP-28C and HP-28S were two graphing calculators produced by Hewlett-Packard from 1986 to 1992. The HP-28C was the first handheld calculator capable of solving equations symbolically. They were replaced by the HP 48 series of calculators, which grew from the menu-driven RPL programming language interface first introduced in these HP-28 series.

HP-28C/S. With the HP-28C, Hewlett-Packard completely revamped the scientific calculator. This model did symbolic math, used named variables, understood many data types and was the first full RPL calculator. (The HP-18C used System RPL internally but didn't make RPL available to the calculator user.) It was extremely powerful with a wealth of ...

凭借其新的点阵屏幕，hp-28c 是惠普第一款显示图形的袖珍计算器。 用户可以控制比例和位置，可以将十字准线移动到绘图上的某个位置，并让计算器将坐标发送到 堆栈 。

2025年2月17日 · The largest, best source on the Internet for software for and information about Hewlett Packard's HP Prime, HP 50g, HP 49G, HP 48 series, HP 38G, and HP 28 series graphic calculators.

Free download of a color scan of the English-language book 'HP-28C Reference Manual' by Hewlett-Packard, which is an advanced user's guide or advanced user's reference for the HP-28C calculator.

2015年2月17日 · The HP-28C was introduced with 2K bytes of storage. The HP-28S replaced it a year later with 32K bytes at the same price. The HP-28S also added: Directories. Directories allowed variables and programs to be grouped together and to allow sets of variables with the same names to be defined in separate directories.

2002年10月23日 · It turns out that the HP-28S is a surprisingly fast unit! It easily beats the Casio fx-880P, Casio fx-2000C, TI-74 and the HP-32SII. Compared to the HP-15C/41CV/CX it is about 20 times as fast. Only the HP-48GX/HP-49G are significantly faster. The RPL programming model is similar to the HP-48GX and HP-49G.

This advanced scientific calculator, to use the maker's phrase, was the first graphing handheld electronic calculator made by Hewlett-Packard. It also was the first HP calculator using algebraic expressions and the first to allow integration and differentiation. …

To start the self test, with the calculator on, press and hold ON and press . The calculator will beep and display a series of vertical bars. You can now press any key to step through a series of tests (each with a different display - one blank.)

HP-28S Famous calculator made by Hewlett-Packard from 1988 – 1992. Memory 32768 bytes for stack, programs and data. Approximately 31.6 kBytes available to the user.