There still is such a thing as a "piano dulcimer" but it's a hammered dulcimer with a different bridge configuration and a different tuning. Dusty Strings actually calls its PD30 and PD40 models "piano dulcimers"; the PD30 has one bridge in the middle of the instrument, and one plays up the chromatic scale by literally playing up the bridge from bottom to top, with each succeeding chromatic note located on the opposite side of the bridge from the chromatic note before it. In other words, you'd play a G on the left side of the bridge, a G# on the right side, an A on the left side, and so forth. The PD40 adds two more bridges, one on each side of the central bridge, to offer an extra octave; there again, one must alternate sides to play up the chromatic scale (G at the leftmost bridge, G# at the rightmost bridge, A at the leftmost bridge, etc.).

Then there's the Hackbrett, similar to the piano dulcimer in that one plays up a chromatic scale by playing up the instrument from bottom to top. The difference here is that the Hackbrett has two bridges, each located near the pinblocks (the part of the instrument where the tuning pins and hitch pins are located). There again (again), one must alternate sides to play up the chromatic scale (G at the leftmost bridge, G# at the rightmost bridge, A at the leftmost bridge, etc.).

The standard hammered dulcimer, however, is tuned to a diatonic scale.... or, more accurately, to succeeding diatonic scales. A chromatic hammered dulcimer is tuned the same but has extra bridges for the sharps and flats not found on the standard model. Makes it more challenging to play up the chromatic scale!