HP-18C
Encyclopedia
The HP-18C was a Hewlett-Packard
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...

 business calculator
Calculator
An electronic calculator is a small, portable, usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators.The first solid-state electronic...

 which was quickly followed by the very similar but greatly improved HP-19B
HP-19B
HP-19B, introduced on January 4, 1988, along with the HP-17B, HP-27S and the HP-28S, and replaced by the HP-19BII in January 1990, was a simplified Hewlett Packard business model calculator, like the 17B. It had a clamshell design, like the HP-18C, HP-28C, 28S.-External links:**...

. The HP-18C was HP's first RPL
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...

-based calculator even though this model was not user programmable. The user did have a solver (another HP first) available, but only had about 1.5 K
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...

 of continuous memory available to store equations.

The calculator had many functions buried in a menu structure. The clamshell design was fairly robust, but the battery door is the Achilles' heel
Achilles' heel
An Achilles’ heel is a deadly weakness in spite of overall strength, that can actually or potentially lead to downfall. While the mythological origin refers to a physical vulnerability, metaphorical references to other attributes or qualities that can lead to downfall are common.- Origin :In Greek...

of this whole line; 18C, 19B, and 28C/S.

External links

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