Super Nintendo

The Super Nintendo — the Super Famicom in Japan — takes cartridges from your roms/super_nes folder and plays them like any other console here. What makes it worth a page of its own is what goes into its cartridge slot.

Three of RetroXR’s expansion units are Super Famicom cartridges, and each turns the machine into something else:

• The Super Game Boy and Super Game Boy 2, below.
• The BS-X, which puts you in the Satellaview’s town — see Satellaview.
• The Sufami Turbo, which takes two small cartridges at once — see Sufami Turbo.

The console wears a stand-in

The Super Nintendo has no modelled shell yet — it spawns as the procedural box. The adapters, their slots and their cartridges are all real objects regardless.

The Super Game Boy

A Super Game Boy is a Super Famicom cartridge with a Game Boy slot in its roof. Push it into the console, drop a Game Boy cartridge into it, and the handheld’s game runs on your television inside a border.

You spawn it from the Super Nintendo card in SPAWN → Games, not from the Game Boy’s — it is a Super Famicom cartridge, even though what it plays is a Game Boy game. The Game Boy cartridge you put in it comes from your ordinary Game Boy library; there is no separate folder and nothing new to import.

It needs bsnes, and RetroXR switches for you

snes9x cannot run a Super Game Boy at any price. Its source defines a Super Game Boy game type right beside the BS-X and Sufami Turbo ones, which makes it look supported, but the constant is vestigial: the adapter is not in the subsystem list the core actually advertises, and a load attempt is refused.

So this stack pins bsnes. A Super Famicom is a snes9x machine in RetroXR until one of these goes into it, at which point the stack’s own core wins and RetroXR switches — and downloads bsnes if you do not have it.

The BIOS is the adapter’s own cartridge

The program a Super Game Boy runs is not in the game you put into it — it is the adapter’s own ROM, and you supply it:

Unit	File	Goes in
Super Game Boy	SGB1.sfc	libretro/system/bsnes/
Super Game Boy 2	SGB2.sfc	libretro/system/bsnes/

Each unit is gated on its own file, so if you have one dump you are offered one adapter. Until the file is there, that adapter is not in the menu at all.

bsnes does not want the boot ROMs

higan and bsnes-mercury ask for sgb1.boot.rom and sgb2.boot.rom. bsnes has both compiled in, so the two .sfc dumps are all you need here.

SGB1 and SGB2 are different machines

This is not a reskin. The original derives its clock from the SNES and runs the Game Boy about 2.4% fast; the 1998 revision carries its own crystal and runs at true handheld speed. Because the cartridge is the program the console runs, handing the core a different dump is the whole of the difference — a core that emulated the adapter internally would have needed an option toggled instead.

Which one you get is decided by the dump, not the filename

bsnes reads the SNES header title at 0x7FC0 — Super GAMEBOY or Super GAMEBOY2 — matches it against its own board database, and takes the oscillator from the board that matched. The filenames above are only where RetroXR looks.

So an SGB1 dump installed as SGB2.sfc gives you two adapters that are both an SGB1, and the spawn gate will not catch it — a checksum mismatch is accepted deliberately. The BIOS / Extras view is where that verdict shows.

What it looks like when it is working

A Game Boy frame is 160×144. A Super Game Boy frame is 256×224, because in SGB mode the SNES is the machine doing the drawing. If your picture is the small one, the adapter is not in play.

Measured against Donkey Kong (SGB Enhanced) with the No-Intro SGB1.sfc: 1596 frames at 256×224, with the arcade-cabinet border drawn in colour around the Game Boy screen.

The border arrives when the game sends its SGB packets, which for Donkey Kong is somewhere past ten seconds — so a blank surround early on is not a fault. A game with no SGB support at all still gets the adapter’s default frame.

Where Super Game Boy saves go

The battery is in the Game Boy cartridge, not in the adapter, so the save belongs to the game you put in — which is what RetroXR models.

bsnes keeps these saves somewhere of its own

bsnes does not expose save RAM through the usual libretro call at all; it writes through its own file layer to libretro/save/bsnes/<rom name>.srm.

Two consequences. The save is keyed to the ROM’s filename rather than to the cartridge the way every other core’s is, so renaming a ROM orphans its save and two copies under different names keep separate ones. And the Saves panel, save backup and netplay’s SRAM transfer all read the other path, so a Super Game Boy save is not yet visible to them. Not reconciled.