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README.md

SA-1 Root: Gradius III

Version 1.5, released 2019-05-31

Gradius 3 is a classic shooting game made by Konami.

This SA-1 Root reduces most of the orignal game's slowdown and lag and minimizes the overall loading time. As a side effect, the game is now much more difficult.

How to Patch

Download the latest Gradius III .bps patch file available on the Releases tab.

You can patch it using beat or FLIPS, both common .bps patchers.

You can also patch the .asm files directly using Asar.

For more information on how to apply ROM patches, see this SnesLab article: https://sneslab.net/wiki/How_to_apply_ROM_patches

It works with both American and Japanese version of Gradius III.

Expected checksums:

JPN Version:

Before patching

  • CRC32: BCA9AB02
  • SHA256: 47DDF3204DC99421F6029EAAED4EAA1A6660B5DDF2F07A5C2CD5879C70CA9043

After patching

  • CRC32: E86AA13A
  • SHA256: 17B9368F84E0C1D5173B80C6B53BB2DD5D4B6A608F6260CA37649F8045F8197F

USA Version:

Before patching:

  • CRC32: CD973979
  • SHA256: 93DA752A0C76167D0907EFA832367E5D14AAB8E835B864F345C386071A9AF718

After patching

  • CRC32: D8EC2C36
  • SHA256: 334119D66AE790D420C90A77DBC2EC2921E8A78B8A3F1222BDA6ACDB4922BEEB

Compatibility

It works on both real hardware (sd2snes or SA-1 cart) and emulators (Snes9x and bsnes/higan).

Technical details

  • Remapping mode: Full
  • Remapping strategy: Runtime
  • SA-1 usage: Aggressive

This game has a very complex data structure. Direct page, indirect addressing and shared ROM/RAM pointers are pretty common on this game. For that, I had to remap the entire RAM memory to the BW-RAM and for the data structures that referenced banks 7E/7F were most of the time remapped by runtime for not having to mine over 450KB of data structures.

SA-1 was used for the maximum time possible and a callback system was used for the SA-1 CPU calling back the SNES CPU when running on routines that it can't handle (APU uploads and PPU updates mostly).

Because of the strategy used, 128 kB (1024 Kbit) of BW-RAM is required to the game run correctly.

RAM remap

  • $0000-$1FFF -> $6000-$7FFF
  • $7E:0000-$7F:FFFF -> $40:0000-$41:FFFF

Credits

Gradius III - SA-1 Root wouldn't be that awesome without help from these people:

  • indcsion (testing)
  • slidelljohn (bug reports and extra help)
  • Vitor Vilela (crazy author that did most of the patches)
  • You (for using it :D)

Contacting me

You can contact me though the following links: