A G1A file is a data file saved in the G1A format used by various Casio graphing calculators, including fx-9860G, fx-9860GII, and fx-CG series calculators. It contains an add-in, which is typically used to add small games or utilities to select Casio graphing calculators. G1A files are written in C programming language.

G1A files are most commonly used by older Casio graphing calculators from the 2000s and were replaced by G2A and .G3A files in newer versions of Casio graphing calculators. Since the files are not meant to be manually opened, you most likely will only encounter the files when transferring programs from or to the storage or main memory directories of a graphing calculator. The Casio FA-124 program allows you to transfer G1A files between your computer and graphing calculator. After copying G1A files to your calculator using FA-124 and a USB cable connection between a PC and the calculator, you can then see the add-in from the main menu when you start the calculator. NOTE: The fx-Manager PLUS Subscription program also allows you to emulate fx- series calculators and open G1A files.