OSD Menu¶

Every MiSTer-DB9 core adds OSD options for direct controllers.

The options¶

The order of values is fixed: Off, Saturn, DB9MD, DB15. Saturn comes first on purpose — see the note below.

Activating from a USB keyboard¶

1. Press F12 to open the OSD.
2. Pick the core's "Settings" submenu (the location varies per core).
3. Set UserIO Joystick to the controller protocol you have wired.
4. Set UserIO Players to 1 or 2.
5. Pick Save settings so the choice survives a reboot.

Automatic detection (userio_auto_select)¶

Set userio_auto_select=1 in /media/fat/MiSTer.ini to let a DB controller configure UserIO Joystick for you. With it enabled:

• Open the OSD and press any button on the DB controller. The core detects which protocol the pad speaks (Saturn / DB9MD / DB15) and sets UserIO Joystick to it automatically — no keyboard or USB/Bluetooth gamepad needed, even for first-time setup.
• A button press always switches to the connected pad. This both enables the pad from Off and corrects a wrong choice: if UserIO Joystick was left on DB15 while a Mega Drive pad is plugged in, pressing the pad snaps the setting to DB9MD. That matters because the OSD live-detects the pad while open, but the saved setting is what drives the game once the OSD closes — so without this you'd see the pad work in the menu but do nothing in-game.
• An idle controller never changes the setting. Detection acts only on an actual button press. If you want to use a USB pad but left a DB adapter plugged in, it won't hijack your setting — leave the DB pad untouched and the value stays put.
• To keep the DB controller disabled, set UserIO Joystick to Off from the keyboard and don't press the DB pad. (A press means "use this pad", so it re-enables.)
• Detection runs only while the OSD is open. During gameplay the saved UserIO Joystick value is used as-is.

Pick Save settings afterwards if you want the detected choice to survive a reboot.

With userio_auto_select=0 (the default), nothing is selected automatically — set UserIO Joystick from the keyboard as described above.

First-time setup without auto-select¶

If userio_auto_select is off, the first time you enable a DB controller you have to use the keyboard — the controller path is still Off, so it can't navigate a core's OSD yet. After you set and save a protocol once, the OSD becomes navigable from the controller. (The boot menu is always navigable with a DB controller regardless of this setting, so you can still load cores with the pad.)

Navigating the OSD with a DB controller¶

After UserIO Joystick is set and saved:

Inserting a coin in arcade cores uses the bit-11 (Mode) slot: Mode on a 6-button MD pad, Start + B on a 3-button MD pad (the DB9MD helper synthesizes Mode from that chord, since a 3-button pad has no Mode button), Select on a DB15 pad, or R on a Saturn pad. See the per-core button notes in controllers/.

Why Saturn comes first¶

When you cycle the UserIO Joystick value, the OSD walks the list in order. If DB9MD were listed before Saturn, plugging in a Saturn pad and clicking once would activate DB9MD first. The DB9MD module would drive the MD SELECT line and read the Saturn pad's data lines as garbage button presses, sending phantom OSD inputs that make it impossible to keep clicking through to Saturn.

Putting Saturn first means: with a Saturn pad connected, the first click goes straight to the right protocol. With a Mega Drive pad connected, even though the cycle visits Saturn first, the Saturn detection logic stays inert (it requires a Saturn-specific signature that a Mega Drive pad cannot accidentally produce), so no ghost inputs reach the menu.