Touch Fin: the financial calculator for Android and iPhone
Figure 1: Touch Fin screenshot - iOS
Touch Fin (formerly known as Touch 12i or Andro12C) is a financial calculator for Android and iPhone. It implements most
features of the industry-standard HP-12C calculator, including programming functions.
Touch Fin uses the same engine of the time-proven
HP-12C Web emulator. It aims to mimic all features (and limitations)
of the real device.
The calculator mimics the HP real device as closely as practically possible,
including details such as rounding up of n
in financial calculations.
the same limitations as the real 12C: only 99 programming steps, 20
memory positions, etc.
Touch the upper right corner of the screen (in paid versions) to open a quick guide for some operations of the
Figure 2: Touch Fin 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
The calculator is offered in four versions: Free (ad-supported), Gold, Palladium
and Black-Scholes Edition
The free version is not time-limited nor crippled in any way whatsoever. The paid versions are ad-free and
have more features that are extrinsic to the calculator.
If you use the free version and like it, consider buying one of the paid versions to support the development
of this app.
Free and paid versions are separate apps — buying the paid version
does not remove the free app from your phone. Each version is updated at a different
time for extra safety: if one version breaks due to some unforeseen problem in update,
the other is still available.
Settings (iPhone version)
This app adds a panel to device Settings. There, you can toggle
decimal point as comma and keypress sound.
Figure 3: Touch Fin screenshot
These items may also be configured within the application screen, using
the following key sequences:
- ON: change number format (American, European, Indian), in free version
- ON: open Settings screen, in paid version
- STO ON: toggle keypress sound
The app implements a menu that is accessible via the Android-standard menu soft button,
by touching the upper left corner of the screen, or by keying RCL EEX.
The free version implements only a subset of the following options.
- Number format: A 3-state menu option to select the number separator style
between American (1,111,111.99), European (1.111.111,99), and Indian (11,11,111.99).
- Key feedback: a 4-state menu option that allows to choose the feedback on
keypress. The available options are: audio click, strong haptic, mild haptic, and none.
- Display > Stretch on/off: a 2-state menu option that toggles the stretch mode.
"Stretching" fills the entire screen with the calculator, in some screens it may look distorted.
Non-stretched mode uses less of the screen but the looks are preserved.
- Display > Fullscreen on/off: a 2-state menu option that toggles the fullscreen mode,
in which the status bar is hidden.
- Display > Never sleep/Allow sleep: prevents the screen to go to sleep when the calculator is at foreground
- Display > Lock landscape/Lock portrait/Allow rotation: options that allow to lock the orientation
- Memory: load/save memory operations.
- Load memory: loads calculator memory from a file.
- Save memory: saves calculator memory to a file. The user has the option of overwriting
an existing memory file or create a new one.
- Delete memory: remove a memory file from the phone.
- Speed: turn on/off fast speed on program execution. Slow speed (the default) mimicks a real device's
speed. Fast speed runs the program as fast as it can.
Saving copies of the memory
The paid versions allow to store and retrieve copies of the memory.
his 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 in iPhone
Use the following key combinations to access this feature (paid versions only):
- STO CHS: save memory. Type a label for the memory and touch OK.
- RCL EEX: load a previously saved memory. Select the memory from the list and touch OK.
- RCL g EEX: delete a previously saved memory.
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 exchange your iPhone for another one.
Figure 4: Touch Fin screenshot
The paid versions offer an alternative vertical layout, good for
using 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 (iPhone) or in the menu (Android).
Free and paid versions
The free and paid versions implement the same calculator. The paid
versions offer many extra features:
The vertical layout can be more practical if you like to use your phone in portrait orientation.
Touch the upper right corner of the screen to see a quick guide for some operations.
||In addition to audible feedback, touched keys
can show a visual feedback. This feature can be turned on and off at Settings, or by keying
RCL g +.
The Android version offers fullscreen mode, as well as different screen filling
methods (stretch vs. non-distorted).
The Android version can prevent the display from sleeping and locking, so the
calculator stays lit on the screen during all the time you need it.
The Android version offers haptic feedback as an option to audible feedback.
|Increased sensitive area
The area around
the keys is also sensitive to touches. You don't need to touch the key spot-on;
touching near the key is enough. Coupled with the visual feedback, this
feature allows faster typing. (Press RCL g ON if you are curious to see the sensitivity map.)
The current calculator memory (including all registers and programming steps) can be
saved. You can save as many memories as you want, e.g. if you have many programs and
want to load them later.
||The development of the paid version is supported directly by you!
(*) make sure you have signed into iCloud (Settings -> iCloud), so the
memories are effectively backed up and shared between your devices.
The calculator is offered in a "Palladium" version, that follows the conventions
of the HP-12C Platinum. It is capable
of algebraic mode (including parentheses) and has more storage: 400 programming
steps and 30 NPV/IRR memory positions.
Figure 5: Screenshot of Touch Fin Palladium
This version is a separate app from the Gold version. It shares all the features of the
Different from typical 12C emulators, this calculator does not implement some seldom-used
features. On the other hand, comprehensive support for Black-Scholes calculations is present.
Figure 6: Touch Fin screenshot
Bonds and depreciation features of 12C are not implemented in this version!
On the other hand, there is comprehensive support for Black-Scholes calculations.
Read our manual to learn how to use Black-Scholes features.
This version is a separate app from the Gold version. It shares all the features of the
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. Other differences:
- Calculations use 15-digit precision,
so there can be minor rounding differences in comparison to a real unit.
- Minus sign in LCD emulation looks different.
- Speed is different; generally this calculator is much faster.
- You can use all programming steps and all STO positions at the same time,
while in the real unit they share the same memory and there is a tradeoff.
- Footer elements like BEGIN, RUN, PRGM etc. occupy different positions.
- Also, there is a slight augmentation in footer elements. For example,
RUN shows the program step, STO-operation shows operation symbol and so on.
- Execution of programs may have a different speed and actual calculations
are shown instead of "Running...".
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.
results against other sources if you are going to take some actual financial
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.
The source code of this software can be found in GitHub repositories for
similar to Briefs'
. The engine is released as free software (MPL 2.0 license).
Also, Rhino is extensively used in development, for building and unit testing.