While the concept is the same, the design is very different; modern versions of the instrument have been more or less based on Heyden's design. An etching of the Geigenwerk from 1620 shows an instrument of about the stature and shape of a harpsichord (i.e., an piano-shape with flat sides and hard angles). The fully chromatic keyboard appears to have 44 keys, extending about three-and-a-half octaves from low E to a high B. (see illustration) This keyboard range is consistent with harpsichords of the day, although harpsichord keyboards more typically started on low C or low F. The number of strings can't be directly determined, but the design implies one string per key, or 44 strings.[3]