The Atari Calculator CX8102 for the Commodore 64

In 1979 Atari shipped a program called "Atari Calculator" for the Atari 800 computers. It provides the functionality of powerful, programmable scientific and financial calculators on the Atari home computer. I heard an interesting talk on it given by Roland B. Wassenberg on the Vintage Computer Festival 2013 in Munich, got interested, and ported this program to the Commodore 64.

The Atari Calculator was written by Carol B. Shaw at Atari. I reverse-engineered her program and moved it to the C64. The I/O routines for the Atari were replaced by equivalent C64 subroutines. The complete Atari floating-point library, which is heavily used by the Calculator program, also had to be ported to the Commodore computer. The functions to load and save Calculator programs and data and the functions to use the printer are still missing in the C64 version. To have a similar look-and-feel as the original, I made a user-defined character font on the C64, which is exactly the same as the Atari 800 font.

The program can be downloaded as a Commodore 64 "prg" file here: calc.prg

You can use this file with a Commodore 64 emulator or put it on a floppy disk and try it on the real machine.

The manual and a lot of information can be found on Carsten Strotmann's great AtariWiki.

In the following you find four screenshots of the running program.