“Gradius (USA)”

Cite as: “Gradius (USA)”
Licence: proprietary; never redistributed (docs/data-policy.md#roms)
Credit: Konami
Notes: No-Intro "Gradius (USA)". NES 2.0 header: 32 KB PRG ROM at $8000-$FFFF, 32 KB CHR ROM, mapper 3 (CNROM), no battery. Without the 16-byte header the SHA-1 is 9282e87c643557682aee674174821bf3a0fe3876. A CPU address $8000-$FFFF is file offset address − $8000 + $10.

Cited on

Claims (3)

In the US NES Gradius each capsule moves the meter's cursor one slot along six, back to the first after the sixth, and a press of the power-up button buys the lit slot and clears the cursor. Taking the slots in the bar's order, Speed Up adds 1 to a speed count; Missile can be bought once; Double and Laser write 2 or 1 to one shared byte, so each replaces the other; Option adds 1 up to 2; and ? sets a shield counter to 5 when it's 0. A slot that can't be bought leaves the cursor where it is.	`0x095B-0x09830x0984-0x09F2`	Code
Start pauses the US NES Gradius, and while it's paused a routine compares each new press with a ten-entry table, Up Up Down Down Left Right Left Right B A: the same ten bytes as Contra's table. A wrong press sends the count back to 0, unlike Contra's, where a miss stores `$FF` and ends the check. The full sequence sets the speed count to 1, buys Missile, sets the options to 2 and the shield counter to 5, and leaves Double or Laser as they were. It also decrements a per-player byte that must not be negative for the check to run.	`0x1AEA-0x1B4D0x1775-0x17940x1795-0x17AC0x1C6E-0x1C7C`	Code
When a player's lives byte drops below 0 in the US NES Gradius, the game-over state waits, for as long as $B0 is nonzero and then 120 frames (`$78`), and meanwhile runs the code check with its other ten-entry table, Down Up B A B A B A B A. If the count has reached ten when the wait ends, the player comes back with the lives byte at 3, the value a new game sets.	`0x17AD-0x17D40x1801-0x18390x170B-0x17740x1795-0x17AC0x0308-0x0316`	Code