“Toccata Chromatica” (subtitled “Echoes of Sweelinck”) was composed especially with the 1671 Pieter Backer organ in the Bonifaciuskerk (St Boniface Church) in Medemblik, Netherlands, in mind. The piece exploits two features of this historic instrument: (1) the 8' Trumpet stop, which does not extend below middle C, and (2) the lack of pedal stops – the pedals operate entirely as pull-downs from the Hoofdwerk, and they take the leading melodic part at the beginning and at the end on high-pitched stops. A further connection between Toccata Chromatica and the Bonifaciuskerk is that the great Netherlands organist and composer Jan Pieterszoon Sweelinck (1562–1621) was married there, so Ad Wammes has based his piece on Sweelinck’s Fantasia Chromatica.

A study of historical fingering led Wammes to give phrasing an important role in his piece by combining phrases of two and three notes, of three and five notes, and of five and eight notes. He has also incorporated the echo effect, frequently used by Sweelinck, the shortest echo being a semiquaver, the longest echo being two bars.

The edition includes composer's note and registration scheme for the Pieter Backer organ in English, German and French.