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README.md

SA-1 Root: Gradius III

Version 1.7, released 2022-09-19

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.

Base and Origin versions

There is two versions available. One is the base SA-1 Root patch, where it activates the SA-1 chip and accelerates the game to the maximum. The BPS files are Gradius-III-JPN.bps and Gradius-III-USA.bps

Another version uses GuyPerfect's spdwn add-on that reduces the speeds of most of the Gradius III bosses, making it closer to the original game speed, but still without slowdown being used. The BPS files are Gradius-III-Origin-JPN.bps and Gradius-III-Origin-USA.bps

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.

Required ROM checksums

Japan (NTSC-J) version

  • CRC32: BCA9AB02
  • SHA256: 47DDF3204DC99421F6029EAAED4EAA1A6660B5DDF2F07A5C2CD5879C70CA9043

USA (NTSC-U) version

  • CRC32: CD973979
  • SHA256: 93DA752A0C76167D0907EFA832367E5D14AAB8E835B864F345C386071A9AF718

Checksums after patching - SA-1 Root

Japan (NTSC-J) version

  • CRC32: C6105027
  • SHA256: A844154BD3887386779E8B796EA9C4FE41715BC03B19C2DEB9B6D1F3AD642540

USA (NTSC-U) version

  • CRC32: F696DD2B
  • SHA256: D5D5BFA8F694DF4524E1C5963D58E9F5857786C2BF46118152DED4C150A3D303

Checksums after patching - SA-1 Root + Origin

Japan (NTSC-J) version

  • CRC32: 7C2E0613
  • SHA256: 186EF215E7C6D18D907AAAB212542B013C69A9125EB4AFA383BBF3F5C4D5D402

USA (NTSC-U) version

  • CRC32: 0317BDB2
  • SHA256: 942B4A3F9C7EC2C2EE187E0C435DD50EE3DBBBE0CDF07B74BD29199D6F833082

Compatibility

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

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:

  • GuyPerfect (Gradius III speed reduction patch add-on)
  • 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: