RPNcalc
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--> This software is for Newton 2.0 and 2.1 Newtons ONLY.
 
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--What is it?

RPNcalc is a small, multi-function RPN calculator intended as a replacement
for the built-in Newton calculator app for those who prefer RPN.  It was designed
to be small in both program size and heap usage.

This program is freeware; if you desire a smaller five-function RPN calculator try
RPNcalc Lite.

--What are the functions?

RPNcalc is a multi-function calculator with an eight entry stack.  Numbers can
be entered in either normal notation (ie. 4.32) or exponential notation (4.3E+2).
At the bottom are two pickers: one selects the display mode for the screen
(floating, fixed 2, fixed 4, and engineering mode) and another selects the trig
mode (degrees, radians, and gradians).

The program has two states: display mode or number editing mode.  While in
number edit mode the bottom line will show on the left side of the display.  In
display mode the bottom line will show the zero stack entry on the right side.

Pressing numbers while in display mode places you in number editing mode, which
remains until either the 'Enter' key is pressed or a numeric operation key is pressed.

The back arrow key removes digits from the number currently being input in
number editing mode, or drops the stack by one if in display mode.

The 'Clear' key removes all numbers in the edit buffer while in number editing
mode; if in display mode pressing clear will cause a 'Clear?' prompt on the top
line.  Pressing 'Clear' again will clear the entire stack, or any other key will
cancel the clear mode.

There are ten memory registers.  To store the bottom stack entry to a register,
press 'Sto' and the memory register, one of the '0'-'9' keys.  To recall a value
from a register into the bottom stack entry, press 'Rcl' and the memory register
number ('0'-'9').

The 'Swap' key will swap the bottom two entries in the stack.

The 'Undo' key can undo all arithmetic operations (but just the last operation
performed), and some stack functions.  It cannot, however, undo stack rotates
(just do the opposite rotation).

--Error messages

The error messages in RPNcalc are pretty basic, and arise from the
floating-point exceptions in the processor on the Newton.  Entering numbers
(or calculating results) larger than1E+308 or smaller than 1E-308 will
produce an 'Overflow' message in the top line of the display.

'Error' will be displayed in the top line of the display if an incorrect key
is pressed, or the square root key is pressed with a negative number in the
stack 0 entry.

--Save state

RPNcalc saves the entries in the stack when the program is closed so
they can be used the next time it is run.  Upon deletion of the program these
entries are removed from the system soup.