http://invisible-island.net/
Copyright © 1996-2012,2013 by Thomas E. Dickey
add is a fixed-point calculator that operates as a full-screen editor. It is designed for use as a checkbook or expense-account balancing tool.
add maintains a running result for each operation. You may scroll to any position in the expression list and modify the list. Enter data by typing numbers (with optional decimal point), separated by operators.
An output transcript may be saved and reloaded for further editing.
I originally wrote this in 1986, to replace a script I'd written for the IBM VM/SP CMS system at the ITT Advanced Technology Center. It's not advanced technology, but invaluable for its intended use.
Later (in 1993), I ported it to MS-DOS using PDCurses (while working on my port of vile). Vile of course did not use PDCurses (it used its own terminal drivers), and this was the first time I had used curses with color. I set it to white-on-blue:
Shortly after (in 1994), I found that ncurses did not behave the same for colors as PDCurses. After some pursuit, I was able to get this fixed (in 1995).
Since then, it has evolved. See the CHANGES for details.