HP-15C

The HP-15C calculator was produced by Hewlett-Packard from 1982 until it was discontinued in 1989. It had an original MSRP of $134.99. The 15C was part of HP’s Voyager line of calculators that began in 1981. The Voyager line, including the 15C, are all programmable calculators and use Reverse Polish Notation. The line included the 10C, 11C, 12C, 15C and 16C. They all look similar but each one has different capabilities and were marketed to different groups of users.

The HP-15C was the advanced scientific calculator in the Voyager lineup and took the place of the earlier HP-34C. In addition to the 34C’s capabilities the 15C can manage matrix operations, complex numbers, numerical integration and root solving. It has a 10 digit, 7 segment LCD display.

Specifications:

• Entry mode: RPN
• Display type: LCD seven-segment display
• Display size: 10 digits
• CPU Processor: HP Nut core (1LF5 / 1LM2 / 1LQ9[1]) / ARM7TDMI core (Atmel AT91SAM7L128) (15C LE)
• Programming language(s): Keystroke programmable (fully merged)
• Memory register: 2…66 registers (R0…R9, R.0/R10…R.9/R20, R21…R65) plus RI, X, Y, Z, T, LAST X
• Program steps: 0…448 lines
• Scientific programmable
• Complex number functions
• Matrix arithmetic
• Solve function
• Integrate function
• Statistical functions
• Linear regression
• Storage arithmetic
• RPN 4 level stack with parallel 4 level stack for complex numbers
• 448 bytes continuous memory
• Default 322 bytes program memory
• Default 21 addressable memory registers
• Single line 10 digit, 7 segment LCD display
• Power consumption: 0.25 mW
• Weight: 113 g
• Dimensions: 128 × 79 × 15 mm

The HP-15C was a very popular calculator. When it was discontinued in 1989 prices shot up on the after market. HP eventually capitalized on this demand and released the HP-15C Limited Edition calculator in 2011. It has the Limited Edition script underneath the logo and you can see that the logo has different coloring as well. Only 10,000 units were made.

Inside, the Limited Edition HP-15C utilizes a newer CPU that emulates the Saturn CPU and runs the original ROM code. Of course, that means that some of the functions run far faster than the original.

Here is a prototype of the HP-15C Limited Edition calculator.

One of the reasons that the original 15C is still so popular is because it does not have alphabetic characters so it can be used in many testing situations that most newer calculators cannot. Of course, it’s small size, portability and horizontal shape are advantageous as well.

The HP-15C is one of the best calculators that Hewlett-Packard ever made. The algorithms used are excellent, the key layout is jam packed but efficient, and it’s size and features are great for almost any situation. Overall it is a fantastic calculator.