GBAdhoc v4.5.0 by ShoshinFauteux

Two PSPs link the way two Game Boys do with a cable, over ad hoc Wi-Fi with no router. Each PSP runs both games and only the button presses travel between them. For Game Boy and Game Boy Color, only the host needs the game. Pokémon Emerald, FireRed and LeafGreen can also use an emulated Wireless Adapter for Union Room trades and battles, and Mystery Gift works from an Android phone with the author's Mystery Gift Station app.

It runs on custom firmware on the PSP-1000, 2000, 3000 and Go. An open replacement for the GBA system ROM is included, and a real gba_bios.bin in the app folder is used if you add one. Unzip it to the root of the Memory Stick and put .gba, .gb and .gbc files in GBAdhoc/roms/.

There's rewind for GBA games (hold Triangle, off by default), five save state slots with pictures, save and state sharing between two PSPs, turbo buttons, CodeBreaker and GameShark codes, and box art. Sleep mode picks the game up where it was. The renderer runs on the Media Engine.

Before linking, switch WLAN on (a setting on the PSP Go) and set both PSPs to the same fixed ad hoc channel, 1, 6 or 11, in Network Settings. Automatic won't work. Both PSPs need the same GBAdhoc version and the same ROM. When upgrading, copy EBOOT.PBP, gbadhoc_me.prx and gbadhoc_home.prx together.

Pokémon MonoMyth is compatible, and demanding GBA games run much faster. 46 test scenes on real PSPs average 26.7% higher frame rates than 4.1.0, and 68% on the scenes that were struggling (under 58 fps on 4.1.0).

Download GBAdhoc-4.5.0.zip and unzip it to the root of your Memory Stick. It installs into PSP/GAME/GBAdhoc, so unzipping over 3.5.0 or 4.0.0 upgrades in place. Your config.ini, saves and save states carry over. Update both PSPs before linking.

> Coming from 4.1.0? It installed into its own PSP/GAME/GBAdhoc410 folder. Copy anything you want to keep from there (saves, save states, config.ini, your cheats folder) into PSP/GAME/GBAdhoc, then delete GBAdhoc410.

Pokémon MonoMyth

MonoMyth turns away inaccurate emulators such as VBA and tells you to use an accurate one like mGBA. 4.1.0 stops on its "emulator is incompatible" screen. 4.5.0 passes its accuracy check and plays on a real PSP, through the intro, the first battles and picking your starter. There are no game-specific hacks: the fix is live timer counters and the ARM7 instruction prefetch window, and every game gets them.

Much faster GBA games

Some GBA games rewrite their own code while they run, and each rewrite used to cost GBAdhoc a lot of work. 4.5.0 redoes only what actually changed.

PSP-3000, Fit scale, sharp bilinear and ambient art on:

| Game | 4.1.0 | 4.5.0 |
|---|--:|--:|
| Doom II | 18.7 fps | 59.0 fps |
| Back to Stone | 17.8 fps | 59.6 fps |
| Duke Nukem Advance | 17.5 fps | 57.8 fps |
| FIFA 07 | 21.8 fps | 59.5 fps |
| Ice Nine | 24.6 fps | 58.5 fps |

A real GBA runs at about 59.7 fps. These are the hardest scenes, so don't read them as a typical 3x. Across all 46 scenes, on both the PSP-1000 and PSP-3000, the CPU does about 25% less work per frame, and scenes under 58 fps went from 18 to 5. The README has the full table.

Also new

• Lower input lag. In light GBA games at full speed, from 4 frames to between 1 and 1.5.
• Link Cable play is in great shape. Every link session we test passes, and speed stays where it was, except Super Street Fighter II Turbo Revival, which dropped about 2 fps.
• Wireless Adapter fixes. An adapter session after a cable session now works, the game is told when the other player leaves, and less lag builds up on the joining PSP. This is a first step: the adapter path still needs work, and more is coming.
• Faster Game Boy and Game Boy Color core, and GBC games no longer hitch every few seconds.
• Better screenshots: small PNGs saved to PICTURE/GBAdhoc.
• New screen filters: LCD grid, dot grid and scanlines.
• Reset game in the in-game menu.
• Fixes. ROMs with accented names show up and open. Need for Speed Underground, Big Mutha Truckers and Street Racing Syndicate start. Sleep is steadier around the menus.

Known issues

Mario Tennis: Power Tour and Mario Golf: Advance Tour over the Wireless Adapter. The link can't keep up: Tennis's connection icon flickers and play hitches constantly; Golf lags and eventually disconnects. The Wireless Adapter path is the focus of the next updates, and they will address both.

Thanks

• KarnFu (#9) sent save states for the games that ran worst and retested build after build on a PSP-1000.
• ChandlerHardy for the sleep fixes (#15, #16, #20).
• u/Far_Froyo_6317 for the filter patch.

Full details are in the README.

Checksums (SHA-256)

4edb093f5750602ec8bbe27b9aac7f44f9d812132ebf61ca85635aab5a55b0ef GBAdhoc-4.5.0.zip
43f3c66c5fbfc9f98951c6d0c6085311918d4fcaa17c962e8953fd0968e177ec EBOOT.PBP
4f4989149f29c984cc6275d5f92993b4f886dc1639275e09ee72ddaa52d54eb6 gbadhoc_me.prx
4cd1b5fcd666ba159686604ac0a3ca86f9fbbf5509f18bdc0b3a64c3298631c9 gbadhoc_home.prx