This is the HP 11C which was introduced to the calculator buying consumer in 1981 and was discontinued in 1989. The 11C is a scientific programmable calculator and had a retail price of $135.00 though by 1989 its price had dropped to $56.00. It featured a landscape liquid crystal display capable of showing 10 numeric digits. The HP 11C was part of Hewlett Packard’s Voyager line of calculators and was only inferior to the top of the line 15C at the time. The Voyager line was HP’s first to incorporate landscape LCD displays and also included the iconic HP 12C financial calculator.
The 11C utilized RPN logic and incorporated some non-programmable features such as Hyperbolic and Inverse Hyperbolic Trigonometric functions, Combinations, Permutations, Factorial, Absolute Value and Percentage Change. It also has 20 storage registers, indirect storage register addressing, Gamma function, and 203 step programming. The 11C had half the memory of the 15C and twice as much as the lower cost 10C.
HP engineers wanted to make the display for the 11C easier to read then previous calculators hence the switch to a large LCD. They also utilized urethane foam washers to help absorb any shock and it was implied that it could withstand a drop from shirt pocket level to the floor. The HP 11C can be opened via screws located under the rubber feet on the back of the unit.
The Hewlett Packard HP 11C is a very popular calculator with collectors. It can bring from $100.00 in average condition to nearly $300.00 in excellent condition and including some accessories such as the box, CD, manual and case.