Abacus The Wersi Abacus The Wersi Abacus Site Design by Bill The Wersi Abacus is a computer based Organ/Arranger that runs on Windows XP, it was first introduced in 2000 and has been continually updated over the years to keep pace with modern sounds and innovations. It was available in various combinations • Abacus KS1 A single manual unit, with the option of adding a lower manual and pedal-board • Abacus Duo Pro A double manual unit with the option of adding a pedal-board • Abacus Duo Deluxe A double manual unit with a pedal-board and additional speakers in the base A selection of pedal-boards are available • A 13 note Spinet pedal-board • A 17 Spinet pedal-board • A 25 note Full pedal-board All pedal-boards included additional foot operated buttons for controling a selection of features on the instrument Additionally an Expression pedal was also available with two side switches The Wersi Abacus Site Design by Bill