It's mostly covered in the data books and app notes. The last version was PALASM 4 V1.5. If you google for "PALASM 4 Ver 1.5 software manual" you'll find the docs on it. http://jason.sdsu.edu/minc/pls_man/e_palasm.pdf looks reasonable as well. PALASM is REALLY dumb. It essentially works at the fuse level.