This is a reproduction of the HP 12CP (Platinum)

Our design goal was to give users a clean 12CP that they could feel comfortable with immediately without the awkward additions found on other iOS implementations of this HP classic. Since CALC 1 contains so many tools for calculations, we did not need to add anything to 12CP reproduction. We just share the stack, TVM values and some storage registers so the user can switch between the 12CP and the many CALC 1 tools.

- The ( ) status indicators are not used since the parenthesis, math operators and right hand value are displayed in ALG mode.
- Text instead of graphics is used for the key labels to take advantage of iOS Dynamic Type. This allows the user to adjust the text size for this calculator. (iOS 10 only). You can also adjust the text size in options.
- An easy to read font was used instead of a 7 segment LED style font for legibility and Dynamic type. This also allows error messages instead of error codes.
- There is no MEM key since there was no need to share memory on an iOS device.
- The number of digits is not limited to 10. CALC 1 uses double precision floating point format for calculations for a maximum of 1e+308.
- There is no added delay when executing a program so the programs run very fast. The R/S is programmed to halt execution during a PSE instruction.
- The ON key from the hardware calculator is not needed so it is a BACK key on standard iPhones to exit the calculator. On plus size iPhones this is used to toggle between a full and compact view in landscape.
- In PRGM mode, there are f-COPY and f-PASTE options to copy and paste the program instructions. This will allow programs to be saved in your Notes apps or sent in emails. More information can be found here, Copy and Paste of 12CP Calculator Programs.

- The stack (x, y, z and t values and last x)
- TVM values: N, i (rate), PV, PMT FV and BEG/END mode.
- Storage registers .0 to .9. CALC 1 uses variables a-z instead of numbered storage and the 12CP .0 to .9 storage registered are copied to the variables used with keys 0-9.

Sharing values allows you to use the 12CP to calculate a payment, then switch to the Amortization Form Calculator to generate a amortization table or graph without re-entering the values. This is just one example of the many tools available in CALC 1.

CALC 1 has separate TVM calculators for annual rate with payments and compounding periods per year and TVM calculators with periodic rates, like the 12CP. When you exit the 12CP, the CALC 1 annual rate is set by multiplying the 12CP periodic rate times the CALC 1 payments per year (P/YR). When you enter the 12CP, only the CALC 1 periodic rate is copied over.

- The calculation mode, RPN or ALG on the 12CP is shared. The ALG mode on the 12CP is the CHN (chain) mode on CALC 1. If you have CALC 1 set to ALG or CHN, the 12CP will be set to ALG. Then when you exit the 12CP, the calculation mode will be CHN in the CALC 1 options.
- The number of digits are shared. If set to more than 9 in CALC 1 it will be reduced to 9 in the 12CP.
- The CALC 1 “use significant digits” options is turned off for the 12CP.
**Key Clicks**and**Haptic Feedback**can be set in the CALC 1 options.

The CALC 1 options are read when the 12C loads. So changes to the CALC 1 Options page while the 12C is loaded (only on an iPad) will not be seen by the 12C until it is loaded. Changes from the 12C options (RPN, ALG, number of digits) will be copied from the 12C to the CALC 1 settings when the 12C is unloaded.

This calculator uses the second and third formula in Time Value of Money Compound Interest Formulas.