The 8 lights correspond to the bits you send to port &FBEE. So it's a little BASIC program (on CPC, not on my laptop here) which sends values 1, 2, 4, 8, 16, 32, 64, 128 and then 64, 32, 12, 8, 4, 2 and then starts again. Between sending the values you put
FRAME:FRAME:FRAME and that's it.