Flies at the player. Speeds in U, V and Z are kept in sixteenths in +$14, +$15 and +$16; each turn each gains 3 towards the player -- U and V towards his legs (PLAYER_U, PLAYER_V), Z towards his body's Z -- up to +56 or down to -72, and the step for the next turn is the speed plus 8 divided by 16, rounding down: at most 4 units a turn either way. Gravity takes one off the Z step before the move (DEC_DZ_AND_UPDATE_UVZ). A move stopped in U or V turns that speed round, so a homer bounces off walls and objects; one stopped in Z keeps its speed (the routine that would turn it, at BOUNCE_Z, is never called).

The half-sizes in U and V are set to 10 every turn, over the 8 of FLYER_TEMPLATE. The four frames are the low two bits of the graphic, from a count in +$10. Some fall from the sky (DROP_GRAPHICS); object template 2 is graphic 48, so a room can start with one too.

The last four instructions are where most moving things' updates finish: bits 4 and 5 of the flags, draw it and copy its rectangle to the screen, and SET_DRAW_OBJS_OVERLAPPED, which marks whatever it overlaps for redrawing.