1. Open the file c:\windows\fnwin.ini using notepad.

2. In the section [Financial Navigator] where the recent files are listed, add the following 2 lines.

Calculator="xxxxx"
Calc.Exe="YYYY.exe"

where xxx is the name that appears in the title bar of the third-party calculator when it is invoked and YYYY.exe is the program name used to activate the special calculator.
For example, this would invoke the notepad as the calculator
Calculator=Notepad
calc.exe=notepad.exe

3. Save the file and exit notepad.

4. Run Financial Navigator and invoke the calculator as normal and the new calculator will appear.

If you want to use this calculator instead of the windows calculator in FN, then
add these 2 lines in the fnwin.ini file in your c:\windows folder. It must be in the
section under
[Financial Navigator]

Calculator="TapeCalc"
calc.exe="C:\Program Files\PC Magazine Utilities\TapeCalc\TapeCalc.exe"

Change the path to be where the TapeCalc.exe is install for your computer. This will be the same as the target in the shortcut create when TapeCalc was installed.