Guys, Before I can start soldering on each tactile switch for cdu, I recongize it has 4 terminals. I know one terminal would be soldered and connect to the row part, and another terminal on would be connected for Bit part. what about the rest of two terminals? Let me know...

Hi Arthur,the other 2 posts may be used just for better fixture of the switch on the board, or they might be connected in parallel.So just find out which are the 2 pins which are closed when the switch is depressed (using an Ohm meter). Make sure the other 2 will not connect to the "active" pins when soldered into the board.Hope this helps.Best regardsPeter