1. A bank note processing machine having the following elements: sensors ( 5 ), a transport system ( 6 ), an input/output device ( 7 ), and a control device ( 3 ) with an associated memory ( 4, 4 a ) which controls the elements of the bank note processing machine by means of software and/or data stored in the memory ( 4, 4 a ), characterized in that the bank note processing machine has an interface ( 1 ) which makes it possible to couple memory systems ( 2 ) of different kinds to the bank note processing machine in order to alter, supplement or replace the software and/or data stored in the memory ( 4, 4 a ).