The ship and its weapons
The ship, the gauge pieces and the items are drawn from the bytes of the ROM. The GIFs are the VRAM of every frame of a game in openMSX, painted the way the TMS9918 paints it (tools/anima.py), one frame in three.
The ship
The fourteen poses.
Two 16 x 16 sprites and fourteen poses (p09:A145-p09:A19F, patterns at
p14:95F7): level, climbing and diving, the same with the shield in front,
and as many again for the vertical stages. The shield takes the hits counted
in IY+22 (p02:960B).
There are two ships: SABEL TIGER, flown by IGGY ROCK, and THRASHER, flown by
ZOWIE SCOTT. The SELECTION screen at p12:B877 asks YES or NO to
«PLAYER1 JOINT GAME».
The weapons
The four options, following the ship along the path it took.
At the bottom, the gauge has seven boxes (p00:5D8E). Each 0x29 capsule
moves the chosen box along (p02:97C9) and the second button activates it
(p02:8929): the box raises its weapon one level, with its routine from the
table at p02:8967. On the right, a 5-character window says what is
carried: a piece from the table at p14:8849, 35 bytes of pattern and one of
colour, chosen by the box and its level (p00:5E52).
The 22 pieces, drawn from the ROM. Those of the seven boxes are identical to
the ones the game paints in openMSX when picking up each capsule
(tools/armas.py coteja).
| Box | Level 1 | Level 2 | Level 3 |
|---|---|---|---|
| 1 | SPEED, seven times | ||
| 2 | NORMAL | TWIN | TRIPLE |
| 3 | 2WAY-B | HAWK WING | HOWMING |
| 4 | RIPPLE | ARMING | |
| 5 | LASER | METEO | SCREW |
| 6 | OPTION, up to four (three with two players) | ||
| 7 | F.FIELD, ten hits |
Each link leads to the ship firing that weapon.
Boxes 2, 4 and 5 are the main weapon (IY+40: 1 NORMAL, 2 RIPPLE, 3 LASER,
4 SCREW, 5 METEO, 6 TWIN and 7 TRIPLE) and box 3 and the ARMING the panel
weapon (IY+41: 1 to 3 the missiles and 4 the ARMING). The game only gives
the second and third levels with both ships joined, in state 3 or 4
(p02:8995), when the window says PILOT or Co.PILOT. For the GIFs the
weapon was set by hand in RAM (0xE340 and 0xE341); the options and the
F.FIELD are activated as in the game. The ARMING goes wherever the
controller is pushed (p03:B43F): with the ship still, it does not fire.
The capsules and the items
Items 1 to 6, drawn with the runs at p09:A331. Items 2 and 3 are
identical, at 0 bytes, to the VRAM of two games in openMSX.
There are three capsules (p02:9670):
- 0x29 moves the gauge box along;
- 0x2A gives a bomb (IY+42,
p02:9806) and the window says T.BOMB: while there are any, the button drops bombs instead of the panel weapon (p03:A962); - 0x35 adds one to IY+1B; at 15 it goes back to 0 and raises IY+10, and
with IY+10 at 7 it gives an extra life (
p02:974A).
The 0x29 and the 0x2A are in the sheet of the stage 4 enemies. The 0x35 has not shown up in any of the recorded games, and it is not drawn here.
Some enemies drop one of these items when destroyed (p01:7C36; with one
player, 1 to 4). They are four characters in the scenery (p02:8B97) and
give 30 points when picked up (p02:9909). Each one sets a clock (0xE630
the mode, 0xE631 the time) and its piece in the window (p02:991E):
| Item | In the window | The clock |
|---|---|---|
| 1 | S.STOP | mode 1, 0x10 |
| 2 | O.HOLD | mode 2, 0x15, and IY+34 = 1 |
| 3 | SPARK | mode 3 |
| 4 | nothing | |
| 5 | mode 5, 0x10, on the other player | |
| 6 | O.CHAIN | mode 6, 0x30 |
Stages 3, 5 and 6 also have items to pick up (p12:A5CE). Picking one up
brings a screen with its result. Item 1 says «IN THE RUIN OF LATIS... YOU
HAVE GOT A CRYSTAL BREEZE» and p01:7B73 sets 0xE30A to 1.