What turned up when we took it apart, with the address of everything so it can be checked.
The credits screen is not a capture: it is four rows of twenty-one characters that 0x51BF lays into the name table, expanded from the compressed text at 0x51E5.
© HAL LABORATORY 1985
PRODUCER F.NAKAMURA
PROGRAMMER S.IWATAThe at sign is the copyright symbol in the cartridge's font, and > is its full stop: you can see both in the pattern table itself. The cartridge is from 1986 and its credits say 1985.
The title screen carries a wordmark that fills half the screen: HOLE IN ONE in block capitals over a red gradient and Professional in a script face over green, with a golf ball for a dot. And it is not stored separately: it is tiles 0xD3 to 0xFF, the same forty-five that in play are the tee, the green and the flag.
The cartridge swaps them by entering one instruction or the next. 0x66D4 is an or 0AFh, the two bytes F6 AF: call there and Z goes clear, and the six calls behind it load the 2 KB block at 0x9F85, which carries the playing tiles. But 0x66C6 ends in a jr $+3 that lands on 0x66D5, the second byte of that same instruction, and 0xAF on its own is xor a: A goes to zero, Z is set, and then the six load only the 360 bytes at 0xAA0E and 0xAAFD, which are the wordmark.
(0xCA40) records which of the two sets is in place, which is why pressing F1 at the menu loads the playing tiles to draw the scorecard and then puts the wordmark's back. The title screen spends 416 of its 768 cells on those forty-five tiles.
This is the big one. When it is the computer's turn, 0x5B39 rolls it some starting values — power between 0x18 and 0x1B, curve between 0x19 and 0x20, the angle to the flag and a club obtained by dividing the distance by eight — and then it enters the loop at 0x5BB4, which plays the whole shot with the real physics.
When it ends it looks at where the ball landed and reacts:
| what happened | what it changes |
|---|---|
| into the water (0x5CB4) | a die decides whether to raise or lower the club, the power, the angle or the curve |
| short (0x5DFA) | fans the angle, or takes a club more and a point of power less |
| too long (0x5E76) | trims the power proportionally |
| out of bounds or bunker (0x5DB4) | drops a club |
| holed out (0x5D95) | knocks a point off, so it does not hole every one |
And hits it again. Until it likes the result, or until it runs out of the tries it has (0xC119, which grows when it is losing: from 4 to 6 when three or more down).
Only then does 0x5408 replay it in front of the player, walking the power and curve bars to the values already decided. What you see is not the shot: it is the re-enactment of the rehearsal. During the rehearsal, (0xC118) set to one switches off the joystick, the frame wait and the drawing, so the dozens of shots the opponent plays fit between two frames.
On the green it does the same with the putt (0x6091), where the starting power is half the distance plus three.
0x629C classifies what is under the ball by tile number: 0x60 to 0x77 trees, 0x94 to 0xB3 bunker, 0xB4 to 0xD1 water. But tiles that straddle two terrains cannot be resolved that way, and for those the cartridge reads the VRAM.
That is what separates fairway from rough, bunker from water, and a bank from everything else. Collision against the scenery is settled by the drawing, and not by a second table someone would have to keep in step with it.
In golf, between two players, the one farther from the hole plays first. 0x46FA does exactly that: it measures both distances with 0x475C — the difference in X and in Y, each in absolute value and halved so they fit, then the root of the sum of squares — and gives the turn to whoever is worse off. If both have reached the green, it also switches to the close-up view.
At 0x5009, one after another with no pointer and no length: bit 7 of the last character marks where each name ends.
C.STRANGE L.WADKINS C.PEETE R.FLOYD C.PAVIN
M.OMEARA C.STADLER B.LANGER T.WATSON F.ZOELLER
R.MALTBIE H.IRWIN T.KITE P.STEWART L.MIZE
H.SUTTON J.SINDELAR J.MAHAFFEY S.BALLESTEROS P.JACOBSEN
L.RINKER B.EASTWOOD D.POOLEY G.BURNS S.SIMPSON
I.AOKI L.NELSON J.NICKLAUS G.NORMAN L.TREVINO
T.NAKAJIMA M.KURAMOTO B.LIETZKE T.OZAKI N.OZAKIAnd the tournament does not simulate them shot by shot. For each hole, 0x4EC9 rolls a die, subtracts the personal difficulty each was dealt at the start of the round (0xC09B), adds their fixed adjustment from the table at 0x5130 — one byte from 0 to 7 per golfer — and looks up which band it falls in. The bands give +2, +1, par, −1 and −2, and there are three tables of bands: which one is used depends on whether the player is under, on, or over par. Against a player who is going well, the field tightens.
With a single player in TOURNAMENT, 0x4F4A also lets you choose which professional you play against, paging the list with the arrows.
0x7005 throws a die modulo nine, and that one number decides two things at once.
Through the table at 0x70F2 it places the ball inside the tee box: 0x7024 adds the entry to (0xCECA), the tee's coordinates in pixels, and the result goes to 0xC63F and 0xC640, the ball in the course view. The offsets run from 3 to 17 pixels, exactly what the tee box measures — three tiles by two — and the grid differs per par.
And through the table at 0x7128, the same number places the hole inside the green: 0x7043 builds from it the cell at 0xCECD, where 0x715F writes tile 0xD6, and the hole's coordinates at 0xC63D and 0xC63E. So where you tee off from and where the pin is when you get there are the same roll.
The flag in the long view, by contrast, is in the script: it is tile 0xE9, and 0x6FA5 notes where it lands. What is rolled, besides the tee spot, are the wind and the green's slope, and the level decides how much.
A hole takes 311 bytes on average, and the trick is in the first three. The cartridge copies them to 0xCEC0 and there they stay. Then, in the script, a 0x3n, 0x4n or 0x5n byte repeats the first, second or third of them n+1 times.
What links the two is a subtraction of three: the index comes from the opcode's high nibble and the table it reads from starts at 0xCEBD, three bytes before the header, exactly so that 3, 4 and 5 land on it. There is no palette table: there is an offset that makes the hole's header be the palette.
It is the same format, byte for byte, as the 1984 Hole in One.
call 0x72D4 that does not point in hereAt 0xBE32 there is a call 072d4h, and 0x72D4 lands in the middle of the course scripts. It is not a tracing error: that address is no longer the cartridge when it executes.
L_BE16 ld a,(0fcc1h) ; EXPTBL[0], the main ROM's slot
ld hl,04000h
jp 00024h ; ENASLT: page 1 becomes the BASIC ROM0x6FD7, 0x700B, 0x72D4 and 0x72E9 are cassette routines in the BASIC ROM. Page 2, where all that code lives, is not touched, which is why it can keep running while its own first half is out of the map. When it is done, 0xBE1B brings it back with the slot init stored at 0xFEDB.
0xB885 is a complete routine — it builds 10×H+L from (0xCEF9) and returns carry if the result is zero or over 18, that is, it validates a hole number — and its two bytes appear nowhere in the ROM. The routine before it ends in a ret, so nothing falls into it either. It is dead code from the editor.