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  • Finance
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RPN-70 SD is a complete simulation of the financial hand-held calculator HP-70 from 1974. It handles loan amortization, saving plans, depreciation, and much more with ease.

What users said:

"Looks good, all functions you need. Love it!"

"This is a beautiful emulation of a very rare HP financial calculator from 1974. Works just like the original but better! Faster, more accurate, with 10 more storage registers, and a popup window lets you see the contents of each stack, financial and storage register. Provides TVM4 functionality for compound interest as well as accumulated simple interest. A true work of art!"

• Photo-realistic look based on an existing device
• Animated keys with click sound (adjustable volume)
• All functions and operations of the HP-70 fully implemented
• Correct wrong number entries by swiping across the display
• Cut/copy/paste of display value
• Double-tap display to view the stack and memory registers
• Visual indicators keep track of input parameters entered
• 10 non-volatile memory registers (not available in original HP-70)

The HP-70 was discontinued after just one year. It is one of the rarest calculators, hard to find in any condition.

RPN-70 SD is a faithful simulation of a vintage HP-70 calculator, as has been verified against a real device using the examples in the Applications Cookbook section of the HP-70 manual. In certain cases, what may appear like a bug of the app is actually an idiosyncrasy of the HP-70.

IMPORTANT: The HP-70 requires exactly three input parameters from the top-row keys, at least one of them being either "n" or "i". In other words, you can't use PMT, PV, and FV as input parameters simultaneously.

A version for the iPhone named "RPN-70 HD" is also available.

Short manual and sample calculations on the website: