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Touch 16i: the programmer calculator for Android

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Touch 16i is a programmer's calculator for Android. It implements most features of the beloved HP-16C model, including programming functions.

Figure 1: Touch 16i main screen

Looking for an iPhone version? Click here to go to Touch RPN.

Get it on Google Play

Figure 2: Some user reviews

Touch 16i uses the same engine of the HP-16C Web emulator. It aims to mimic all features (and limitations) of the real device.


The calculator mimics the 16C as closely as practically possible, and shares the same limitations of the real 16C: only 203 programming steps, 32 memory positions, etc.

The only major deviation is the "extra" information that is shown left and right of the display, to aid working with large integer numbers. If you don't like it, keep pressing ON to toggle modes, until it is removed from screen.

Note that it starts up in integer mode and wordsize of 16 bits. The first thing you will probably want to do is to change the wordsize to 64 bits (the maximum supported). Press 0, f, STO/WSIZE.

The 16C operation is counterintuitive in many aspects. The manual can be found online in PDF format. I plan to write an on-line and user-friendly manual; meanwhile, you can ask anything in the Comments section of this page.

Touch the upper right corner of the screen to open a quick guide for some operations of the calculator:

Figure 3: Touch16i quick guide

Touch the upper left corner to copy the displayed value (the X register) to the clipboard. The value is copied in a "spreadsheet-friendly" format: no thousand separators and point as decimal separator.


Press the ON button to access the Settings panel.

Saving copies of the memory

This is especially useful to have many different programs available and ready to use (perhaps the programs would not fit in the memory all at once, or it is simply inconvenient to have them all in the same memory image). In any case, the whole memory, including all registers and configurations, is saved along with the program.

The memory operations can be found in the Settings panel.

Vertical layout

By default the layout follows the phone orientation. If you prefer to use a single layout all the time, you can lock it to vertical or horizontal at Settings.

Figure 4: Touch16i screenshot

Hardware keyboard

If you have a hardware keyboard (USB or Bluetooth) connected to your phone, you can use some shortcuts to operate the calculator.

A B C D E F 7 8 9 /: U T I J K L 4 5 6 X* [ ] N Y Z return space 1 2 3 - O M G S R 0 . H +=

Differences from real calculator

First of all, it is important to mention that the calculator engine does not use a ROM dump. It is a clean-room implementation, based mainly on calculator's manual plus experimentation. So the results simply can not guaranteed to be exactly equal.

The main interface deviation is the ON key that opens Settings instead of turning off the calculator. Other known deviations:

Terms of use

The calculator is offered "as is". There are no guarantees of precision, exactness, or aplicability to any given purpose. The developer has no responsability for any damages incurring from usage of this software.

Privacy policy

The app does not send any user data to any remote party, and it does not share data with other apps.

When the user saves copies of the memory, they are written as files in the "storage area". Files in this area can be manipulated by any other app installed on the same phone. If this is a problem, remove these files from the SD Card once they fulfill their intended usage.


Please use the comment section at this page, or contact me by e-mail if you have any issues or feedback.

Source code

The source code of this software can be found at GitHub.

Third-party licenses

Rhino Javascript engine

This calculator may include the Rhino Javascript engine. The engine is released as free software (MPL 2.0 license). Also, Rhino is extensively used in development, for building and unit testing.

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