[tsaoyu]

I remember the fun time when I hacking into a CASIO fx-82ES. There is a unsolder jumper on PCB that can 'upgrade' 82ES to 991ES which has four more functions. http://www.instructables.com/id/Upgrade-your-Casio-fx-82es-i...

The quality of those calculators are amazing, thanks for creating all of those, R.I.P