RPN-70 HD

RPN-70 HD is a complete, photo-realistic 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:
"Hard to find a decent calculator on iPad, try this one."
"I don't normally write reviews but RPN-70 is just too fantastic to not get excited about. Apple should list this app under their Education category in the App Store and make it a must have for every college bound student. It is the best HP emulator in the market."
"An incredibly well-engineered calculator app, and free, to boot!"
"This is a really cool Financial calculator. Just like using the original HP-70. Accurate to the penny."

Features:
• Photo-realistic look based on an existing device
• "Live" register view in landscape mode
• Animated keys with click sound (adjustable volume)
• All functions and operations of the HP-70 fully implemented
• Simulation of the HP-70's computation time (optional)
• Correct wrong number entries by swiping left across the display
• Cut/copy/paste of display value
• Visual indicators keep track of stored input parameters (optional)
• Stack shown right below display (optional)
• 10 non-volatile memory registers (optional)
• Built-in short manual with many examples
The HP-70 was discontinued after just one year. It is one of the rarest calculators, hard to find in any condition.
NOTE:
RPN-70 HD 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 SD" is also available.
Visit the website: www.cuveesoft.ch