9420 Tablet Keyboard is a free Thai/English keyboard software (with built-in "Full" Thai/English word database) that designs for tablet devices and optimizes for text-hungry apps like Line, Twitter, This software is based on R4. 0. By Solution 9420. Updates see. "Twitter. com/9420TKB". or. www. solution9420. com. (First published date: Mar 3nd, 2010).