Got back on track, and the hardware has encountered some problems, so now I just panic-write the simulation version to "pass" the exam - maybe I'll get back to the hardware version before deadline.
Had not fun debugging a strange overwriting of the few variables I have in SRAM. Minor syntax detail, if you write
"nothing" happens., i.e. the DATA and MORE occupy the same byte. You need to write
data: .byte 0
more: .byte 0
Says so i the manual, but other compilers will reserve space and the inital value is optional.