Site menu Touch 16i: the programmer calculator for iPhone and Android
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Touch 16i: the programmer calculator for iPhone and Android

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Touch 16i is a programmer's calculator for Android, iPhone and iPod Touch. It implements most features of the beloved HP-16C model, including programming functions. Available at App Store.

Figure 1: Touch 16i screenshot - iOS

Figure 2: Touch 16i screenshot - Android

Get it at App Store

Get it on Google Play

Emulators of Hp-1xc RPN calculators by EPx

Figure 3: 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 4: 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" or "data entry-friendly" format, that is: no thousand separators and point as decimal separator.

Settings (iPhone)

Figure 5: Touch16i screenshot

This app adds a panel to device Settings. There, you can toggle decimal point as comma and keypress sound.

These items may also be configured within the application screen, using the following 'apocryphal' key sequences:

The app implements a menu that is accessible via the Android-standard menu soft button, by touching the left upper part of the screen, or by keying RCL BIN.

Saving copies of the memory

The app allows to store and retrieve 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.

Saving copies of the memory (iPhone)

Use the following key combinations to access this feature: The memories are stored locally as well as in iCloud. If you have configured iCloud in your devices, you can transfer memories between devices, provided that they are configured with the same iCloud account. Also, a new device will have access to the previously saved memories, so you don't lose anything when you replace your iPhone.

Vertical layout

Figure 6: Touch16i screenshot

The software offers an alternative vertical layout. It may be more practical if you prefer to work with the phone in vertical (portrait) position.

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

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.

In Android, 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. The license is similar to Briefs'.

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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