INIT (0x4064) sets the stack at 0xE400, zeroes the game's RAM, writes a jp 0x4022 into the H.KEYI hook, sets up the VDP and the PSG, loads twelve starting values into 0xE053 — and then falls into a jr to itself at 0x40A0 and stays there for ever.
Everything happens inside the interrupt. Each frame it steps the sound (0x7696), reads the controls (0x44AD) and gives the game one step (0x40AB). 0xE005 is the latch: if the previous step has not finished, the interrupt only moves the sound and leaves.
0xE000 is the state and 0xE001 the sub-state. The state indexes an eleven-word table and the sub-state splits each handler with a djnz chain, so a handler reads like a list of numbered sub-states.
0 title, curtain and labels 6 the event's frame
1 wait 7 end of attempt
2 change of event 8 end of the event
3 prepare the game 9 change of event
4 set the event up 10 the table of records
5 prepare the attemptEvery jump by index goes through the same seven instructions at 0x4046:
add a,a
pop hl ; the return address is the table
call HL_MAS_A
ld e,(hl)
inc hl
ld d,(hl)
ex de,hl
jp (hl)The word table is glued right behind the call, and the dispatcher pops it off the stack. There are ten of them (0x40C8, 0x4B80, 0x4BB1, 0x4CD0, 0x4DFE, 0x4EC4, 0x5054, 0x5151, 0x5297, 0x547C), and each one is declared in src/hypersports2.nocode. A tracer that walks past a call DESPACHA eats the table as instructions and reports coverage it has not earned: the size of each table is fixed by its lowest forward destination, and every one of them closes exactly against it.
Because the dispatcher jumps and never comes back, whatever has to run afterwards is pushed on the stack beforehand:
ld hl,04cc8h
push hl
ld a,(0e080h)
call DESPACHAFour addresses reach the listing that way and no other: 0x4CC8, 0x521C, 0x44E6 and 0x4F87. Two of them were sitting in the notes as data until the pattern was searched for on purpose — a ld hl,NN and a push hl with up to three instructions in between.
Each event has its own step table — seven words for the archery (0x5297), eleven for the weight lifting (0x5151) — and both of them reuse the skeet's steps for what does not change: saving the mark (0x4FD6), checking against the qualifying score (0x4FEA), the end (0x501A) and finishing the event (0x50DC). Four of the eleven weight lifting steps and four of the archery's seven are the skeet's, pointed at from another table and untouched.
tools/mkasm.py builds it from the trace and the notes. Two guards run on every build:
check_trace.py and check_datos_como_codigo.py: no byte declared as data may come out as an instruction. Reassembling cannot catch this — the bytes are the same either way, only what we say about them changes.check_entradas.py: no entry point may fall inside a data range.And presupuesto.py refuses to pass if a single byte of the 16,384 is left unassigned.