I wrote and tested SuperH assembly on the Jornada. The 32X and Dreamcast both use a SuperH CPU like the Jornada, so if the assembly works on the Jornada (baring some instruction set differences), it works on the others.

In particular, one thing I worked on blitting code for the Jornada and 32X. It would draw directly from RLE compressed graphics which would save RAM and speed up some operations. Like if there was several transparent pixels in a row, it could skip over the pixels in one go and instead of having to read each transparent pixel, compare it to the transparent value, then skip over it.