A device is provided for accessing circuit units via access registers. The circuit units have a plurality of inputs for access to said circuit units. A first access register having register outputs which are connected to a first part of the inputs of at least one first circuit unit, and having register outputs which are connected to inputs of at least one second circuit unit is provided. In addition, a second access register having register outputs which are connected to a second part of the inputs of said at least one first circuit unit, and having register outputs connected to inputs of at least one third circuit unit is provided. Moreover, an access register is provided which has a number of register inputs, first register outputs for driving the inputs of at least one first circuit unit, each register input having associated therewith a first register output, and second register outputs for driving part of the inputs of at least one second circuit unit, a subset of the register inputs having associated therewith a second register output.